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  • Electronic Resource  (550)
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  • 1
    Electronic Resource
    Electronic Resource
    The isoprostanes: Unique bioactive products of lipid peroxidation (1998)
    Springer
    Journal of biomedical science 5 (1998), S. 415-420 
    Details
    ISSN: 1423-0127
    Keywords: Isoprostanes ; Oxidative stress ; Lipid peroxidation ; Gas chromatography ; Mass spectrometry ; Human disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The development of a specific, reliable and noninvasive method for measuring oxidative stress in humans is essential for establishing the role of free radicals in human diseases. Currently, accurate techniques to assess oxidant injury in vivo are extremely limited although a number of approaches are being investigated. Of these, the measurement of specific products of nonenzymatic lipid peroxidation, the F2-isoprostanes (F2-IsoPs), appears to be a more accurate marker of oxidative stress in vivo in humans than other available methods. The purpose of this brief review is to acquaint the reader with the IsoPs from a biochemical perspective and to provide information regarding the utility of quantifying these compounds as indicators of oxidant stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02255929
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  • 2
    Electronic Resource
    Electronic Resource
    Quantitative determination of carbohydrates in orange juice by gas chromatography (1998)
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 206 (1998), S. 48-51 
    Details
    ISSN: 1431-4630
    Keywords: Key words Carbohydrates ; Myo-inositol ; Orange juice quality ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  A gas chromatographic method using a capillary column is described for the quantitative analysis of fructose, glucose, sucrose and myo-inositol in orange juice. The method is evaluated for precision and recovery using phenyl-β-glucoside as an internal standard. The results support the suitability of the method. Carbohydrates (fructose, glucose, sucrose and myo-inositol) were determined in different kinds of orange juice. The determination of carbohydrate composition and ratios of the carbohydrate constituents provide a method to assess orange juice quality, especially the myo-inositol content and myo-inositol/fructose ratio. These new indices, which were found to be lower in samples made from concentrates, provide information on the quality and genuineness of orange juice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050212
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  • 3
    Electronic Resource
    Electronic Resource
    Amounts of conjugated linoleic acid (CLA) in German foods and evaluation of daily intake (1998)
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 206 (1998), S. 77-82 
    Details
    ISSN: 1431-4630
    Keywords: Key words Anticarcinogen ; CLA ; Conjugated linoleic acid ; Daily intake ; Foods ; Gas chromatography ; Lipids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The quantities of the biologically active isomer of conjugated linoleic acid (CLA) – C18:2 c9t11 – in 139 German foods were analysed by capillary gas chromatography (results are given as a % of all identified fatty acid methyl esters). The CLA content ranged from 0.40% (Gouda) to 1.70% (Jurassic cheese, Old Emmentaler) in dairy products, from 0.11% (rabbit) to 1.20% (lamb) in meat, and from 0.01% (pike-perch) to 0.09% (carp) in fish. CLA could be detected in neither vegetable fats or oils nor in margarines (CLA 〈0.01%). Crisps, chocolates, cakes and pastries, and other foods have only a negligible CLA content. The average estimated CLA intake in Germany was calculated to be 0.35g CLA/day for women and 0.43g CLA/day for men.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050218
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of gas chromatographic methods for analysis of butyric acid in milk fat and fats containing milk fat (1998)
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 206 (1998), S. 213-216 
    Details
    ISSN: 1431-4630
    Keywords: Key words Milk fat ; Mixed fat ; Milk fat content ; Butyric acid ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The analysis of butyric acid (C4) is of importance for the determination of the proportion of milk fat in mixed fats. Three gas chromatographic methods were compared with regard to their precision for the measurement of C4, i.e. analysis of butyric acid methyl ester after trans-esterification of fat by sodium methylate (method A) or trimethyl sulphonium hydroxide (method B), as well as analysis of free butyric acid (method C), using an internal standard with each method. The examination of 30 milk fats which varied greatly in terms of their C4 content, using methods A, B and C, resulted in mean values of C4 of 3.42 g/100 g fat, 3.71 g/100 g fat and 3.06 g/100 g fat, respectively. The value determined using method B seemed too high, and this may have been due to the presence of co-eluting artefacts, whereas the value determined using method C was clearly too low, and can probably be attributed to losses during sample preparation. The standard deviation (SD) of 0.015 obtained from repeated analyses using method A was quite good. Results obtained using methods B and C had SDs of 0.029 and 0.074, respectively. Different levels of free fatty acids did not affect the results obtained using method A. When method A was checked by analysis of the reference fat, CRM 164, the C4 level determined was found to deviate from the certified C4 content of 3.49 (± 0.06) g/100 g fat by only 0.05 g C4/fat 100 g. Thus method A proved the most suitable for the determination of the proportion of milk fat in mixed fats by analysis of butyric acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050245
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  • 5
    Electronic Resource
    Electronic Resource
    Changes in free monosaccharides during storage of some UHT milks: a preliminary study (1998)
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 207 (1998), S. 180-181 
    Details
    ISSN: 1431-4630
    Keywords: Key words UHT milk ; Storage ; Monosaccharides ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Changes in the free monosaccharide fraction and non-casein nitrogen during the 3-month storage of five batches of commercial UHT milk were studied. Batches with high residual proteolytic activity showed a considerable increase in galactose, N–acetyl glucosamine and N–acetyl galactosamine levels during the storage period, whereas their glucose and myo-inositol contents remained unaltered. In batches with slight or negligible proteolytic activity no changes in the free monosaccharide fraction were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002170050315
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  • 6
    Electronic Resource
    Electronic Resource
    Application of a new method for analysis of exhaled gas in critically ill patients (1998)
    Springer
    Intensive care medicine 24 (1998), S. 415-421 
    Details
    ISSN: 1432-1238
    Keywords: Key words Acetone ; Gas chromatography ; Isoprene ; Lipid peroxidation ; Microwave desorption ; N-pentane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objective: Application of a new method for analysis of exhaled gas in critically ill patients. Design: Open study. Setting: Surgical intensive care unit of an university hospital. Patients: Thirty-seven consecutive, critically ill, mechanically ventilated patients. Interventions: None. Measurements and results: Chemical analysis of the patient's exhaled gas was based upon substance adsorption and concentration onto activated charcoal, microwave desorption and gas chromatographic separation. Patients with acute respiratory distress syndrome (ARDS) exhaled less isoprene than those without ARDS [9.8 (8.2–21.6) vs 21.8 (13.9–41.4) nmol/m2 per min [median (95 % confidence interval)], p = 0.04]. In patients who developed pulmonary infection, pentane elimination increased from 0.4 (0.0–5.4) to 2.7 (0.6–6.1, p = 0.05) nmol/m2 per min and isoprene elimination decreased from 5.2 (0–33) to 5.0 (0–17, p = 0.05) nmol/m2 per min, resulting in a significant increase in pentane/isoprene ratio from 0.1 (0–0.3) to 0.4 (0–15, p = 0.007) when compared to patients without pulmonary infection. Conclusions: The new method allows quantitative analysis of human gas samples with low substance concentrations and is well suited for clinical studies which involve the investigation of metabolic processes in the lung and the body.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001340050589
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  • 7
    Electronic Resource
    Electronic Resource
    Mixing in Stars and the Evolution of the 3He Abundance (1998)
    Springer
    Space science reviews 84 (1998), S. 199-206 
    Details
    ISSN: 1572-9672
    Keywords: Nuclear reactions ; Nucleosynthesis ; Abundances ; Stars:Evolution ; Interior ; Rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We first recall the observational and theoretical facts that constitute the so-called 3He problem. We then review the chemical anomalies that could be related to the destruction of 3He in red giants stars. We show how a simple consistent mechanism can lead to the destruction of 3He in low mass stars and simultaneously account for the low 12C/13C ratios and low lithium abundances observed in giant stars of different populations. This process should both naturally account for the recent measurements of 3He/H in galactic HII regions and allow for high values of 3He observed in some planetary nebulae. We propose a simple statistical estimation of the fraction of stars that may be affected by this process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005027519798
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  • 8
    Electronic Resource
    Electronic Resource
    Large-volume PTV injection: Comparison of direct water injection and in-vial extraction for GC analysis of triazines (1998)
    Springer
    Chromatographia 47 (1998), S. 35-41 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Programmed-temperature vaporization (PTV) ; Large-volume injection ; Direct water injection ; Triazines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The potential of large-volume PTV injection was studied for the analysis of triazine herbicides in water samples. Direct water injection and in-vial extraction were described and compared. Detection limits were between 0.01–0.02 μg L−1 and relative standard deviations were 〈9%. Both methods are suitable for the analysis of triazines at ppt-level, although in-vial extraction is favourable for water samples with relatively large amounts of matrix components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466783
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  • 9
    Electronic Resource
    Electronic Resource
    Development of gas chromatographic method for determination of cholesterol oxides in meat products (1998)
    Springer
    Chromatographia 47 (1998), S. 42-48 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Cholesterol oxides ; Cholesterol oxidation products (COPs) ; Meat products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method of extraction, purification and gas chromatographic analysis of five cholesterol oxidation products (COPs) (7β-hydroxycholesterol, 5α, 6α-epoxycholesterol, 25-hydroxycholesterol, 7-ketocholesterol and cholestane-3β, 5α, 6β-triol) has been developed. The method is aimed at the determination of COPs in meat and meat products, in particular dry sausages, where large differences in the content of cholesterol and its oxidation derivatives may occur. Linearity of response of trimethylsilyl ethers was defined. The minimum concentration tested was 2.5 μg g−1 in the injected solution. The main feature of the present work is the addition of a purification step of unsaponifiables by SPE on silica cartridges. Extraction recoveries of COP standard mixtures, performed with or without the SPE step, are evaluated. The introduction of the clean-up step results in high purity samples without further losses in the entire process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466784
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  • 10
    Electronic Resource
    Electronic Resource
    Fast determination of VOCs in workplace air by solid-phase extraction and gas chromatography-mass spectrometry (1998)
    Springer
    Chromatographia 47 (1998), S. 57-62 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase extraction ; Graphitized carbon black ; Volatile organic compounds ; Workplace air
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A fast, simple, and reliable method is presented for the determination of atmospheric semi-volatile organic pollutants at μg m−3 levels. The method has been used to monitor potentially carcinogenic toxic compounds to which workers are exposed in workplaces, and to measure the same compounds in outdoor air.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466786
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  • 11
    Electronic Resource
    Electronic Resource
    Interaction studies of vinychloride with liquid foods by gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 63-71 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid foods ; Food packaging materials ; Vinylchloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The interaction of vinylchloride (VC) with liquid foods, such as water, olive oil and honey, was studied using the relatively new technique of Reversed-Flow Gas Chromatography (RFGC). The RFGC method permits the calculation of the VC diffusion coefficient in the liquid phase (water, oil and honey) and the determination of the partition coefficient of VC between the liquid and the carrier gas, as well as the determination of the Henry's constant of VC in the liquid food. From the variation of the above parameters with temperature, thermodynamic parameters (free and excess free energies, enthalpies, entropies and activity coefficients) were calculated for the adsorption of VC by liquid foods. These are discussed in comparison with the same parameters calculated from empirical equations or determined experimentally by other techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466787
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  • 12
    Electronic Resource
    Electronic Resource
    Fundamental relationships in gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 570-574 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Compressibility correction factor ; Specific retention volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The exact definition of the compressibility correction factor,j, has been extensively discussed in recent literature. In this work, it is shown that this compressibility correction factor has several different interpretations; however, the simplest and most useful meaning involves a correction from the experimentally accessible pressure at the outlet of a column to the average pressure in the column. Also, an unconventional definition of the retention volume of a solute in terms of the sample size and the equilibrium concentration of the solute in the mobile phase is presented. This retention volume definition is presented as an alternative to the common definition ofV R as the volume of carrier gas which passes through the column in a period of time called the retention time. In this discussion, it is emphasized that the temeprature dependence of the specific retention volume is determined by the thermodynamics of the phase distribution process for the solute and not by an equation-of-state for the carrier gas. Finally, the conventional correction of the specific retention volume by a factor of 273/T c can be used to correct a volume of carrier gas to a pseudo-standard state of 273 K and the average pressure in the column; however, this corrected specific retention volume has no relation to the specific retention volume that would be experimentally obtained at this standard state temperature and pressure. compressibility correction factor, and specific retention volume, were examined with regard to the physical interpretation, exact definition and appropriate standard states to be applied to these commonly reported chromatographic parameters. Such arcane discussions are beneficial to the health of science but may lead to confusion among potential and practicing chromatographers. In order to prevent or at least help ameliorate this problem, the following discussion presents a somewhat unorthodox interpretation of the questioned terms along with a pseudo-physical explanation of the so-called retention volume which is ubiquitous throughout the chromatographic literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467497
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  • 13
    Electronic Resource
    Electronic Resource
    Determination of chlorobenzenes in environmental samples using solid phase microextraction, thermal desorption and analysis by gas chromatography coupled to FID, ECD, MSD, IRD detectors (1998)
    Springer
    Chromatographia 48 (1998), S. 74-80 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; SPME ; Soil and groundwater samples ; Chlorobenzenes ; Thermal desorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A complex method was developed for the determination of chlorobenzenes in soil and groundwater samples. Samples were taken at two sites in Baranya county, where a mixture of chlorobenzene waste was deposited, causing severe contamination in the environment. Clean-up of these sites demands modern and reliable analytical methods. Several sample preparation techniques were used, such as solid phase microextraction (SPME), supercritical fluid extraction (SFE), and a recently developed thermal desorption method. The applicability of various sample preparation methods was compared by measuring recovery percentages, relative standard deviations and by investigating the matrix dependency of these values. Gas chromatography was used for quantitative determination of chlorobenzenes, using MS, IR, FID and ECD detection techniques. Detection levels were as low as 1 ppt in water, and 10 ppt in soil samples. Chlorobenzene concentration was in the range 1 ppt-1 ppm in water and 100 ppb-100 ppm in soil samples. Identification and calibration of these compounds were performed by quantitative standards. This complex analytical method can be used for rapid and precise quantitative and qualitative determination of chlorobenzenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467520
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  • 14
    Electronic Resource
    Electronic Resource
    Quantitative analysis of apolar polysiloxane phases in large-bore capillary columns (1998)
    Springer
    Chromatographia 47 (1998), S. 305-308 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silicone phases ; Film thickness ; Large-bore capillary columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A technique is described for determination of the amount of bonded phase in commercial columns. It is adapted to the determination of the real nature and the thickness of a siloxane bonded film. Ten-centimeter samples of column are used. The method is tested for large-bore capillary columns. Applications to kinetic studies are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466536
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  • 15
    Electronic Resource
    Electronic Resource
    On-line sample treatment—capillary gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 313-345 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sample pretreatment ; Coupling on-line to capillary GC ; Robotization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Sample pretreatment is often the bottleneck of a tracelevel analytical procedure. In order to increase performance, increasing attention is therefore being devoted to combining sample pretreatment on-line with the separation technique that has to be used. In the present review, a variety of procedures in use today for sample treatment coupled on-line to capillary gas chromatography (GC) is briefly discussed. Special attention is devoted to coupled-column techniques such as SPE-GC and LC-GC (SPE, solid-phase extraction; LC, column liquid chromatography) which are topics of much current interest, also because of their frequent use in so-called hyphenated systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466538
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  • 16
    Electronic Resource
    Electronic Resource
    Capillary gas chromatography of urinary steroids of terbutaline-treated asthmatic children (1998)
    Springer
    Chromatographia 48 (1998), S. 163-165 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase extraction ; Urinary steroids ; Terbutaline treatment ; Asthmatic children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Steroid metabolites have been measured by capillary gas chromatography in the urine of 38 children aged 3–6 years. The children comprised three groups: those with asthma being treated with Terbutaline (13), children with asthma but not undergoing treatment (17), and control children in hospital but free from endocrine diseases (8). There were significant (P〈0.05) differences between the amounts of steroids excreted by the different groups of children. Terbutaline therapy led to elevated levels of tetrahydrocortisone, androstenediol, 11-ketopregnanetriol and a reduced ratio of androgen to cortisol metabolites compared with those for untreated asthmatic children. We assume that Terbutaline does not have a steroid-like mechanism of action but acts by modification of the activity of several adrenocortical enzymes. We suggest a hypothesis whereby the antiasthmatic effect of Terbutaline could not only be a connected with its well-known mechanism of action, but it might be explained as a result of the modification of the production of certain glucocorticoids and androgen hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467536
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  • 17
    Electronic Resource
    Electronic Resource
    Separation of positional isomers on polymeric calix[4]arene-siloxane stationary phases in capillary GC (1998)
    Springer
    Chromatographia 48 (1998), S. 422-426 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Calix[4]arene-tetramethyldisiloxane stationary phases ; Geometric and positional isomer separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Poly(p-tert-butyldimethoxydipropyloxycalix[4]arene-tetramethyldisiloxane) (TBCX-TMDS) and poly(dimethoxydipropyloxycalix[4]arene-tetramethyl-disiloxane) (CX-TMDS), have been prepared and used as stationary phases for isothermal capillary gas chromatographic separations of positional isomers. Retention factors and separation factors for the isomers were measured. The isomers investigated were well-resolved on the two phases. Retention of all the solutes investigated is greater on TBCX-TMDS than on CX-TMDS, probably because of extra dispersive interactions of the solutes with thetert-butyl groups of the phase. Separation factors for closely-eluting isomer pairs are similar on the two phases. This seems to indicate either that the solutes are retained by non-inclusion processes or that if the isomer molecules do enter the cavity of the calixarene, i.e. the solute is retained by inclusion, thetert-butyl groups do not play a role in discriminating between the isomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467714
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  • 18
    Electronic Resource
    Electronic Resource
    Determination of triethanolamine in air samples by gas chromatography-mass spectrometry (1998)
    Springer
    Chromatographia 48 (1998), S. 443-449 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas chromatography-mass spectrometry ; Triethanolamine in air
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Low amounts of triethanolamine, collected in ORBO 53 tubes during air sampling, required the development of a very sensitive method for determination. After desorption and silylation reaction with trimethylsilyl imidazole/trimethyl chlorosilane, the derivative was analyzed by gas chromatography-mass spectrometry on an Ultra 2 silica capillary column in single ion monitoring mode (retention time: about 6 min). The method has a detection limit of 1–2 pg with a desorption efficiency of about 81%. Linearity of response was ascertained in the ranges 10–100 ng and 100–1000 ng. Short-term method validation was carried out by intra- and inter-day assays on three amounts for each reference calibration curve. All results satisfied the pre-defined acceptance criteria. In general, the whole procedure was easily performed and was appropriate for our needs. Breakthrough volume was appropriate for our needs. Breakthrough volume was determined on authentic samples and was about 40–60 L, using a flow rate of 1 L·min−1. The amounts of triethanolamine found in the samples ranged from 150 to 250 ng (about 2.5–4.2 μg·m−3).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467718
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  • 19
    Electronic Resource
    Electronic Resource
    Monitoring of optical isomers of chiral alcohols and derivatives by chiral gas chromatography. Effect of derivatization on the enantio-differentiation (1998)
    Springer
    Chromatographia 48 (1998), S. 81-85 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Chiral separation ; Alcohols ; Diols ; Trimethylsilylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatographic chiral separation of several chiral 2-and 3-alkanols and diols was studied both in their free hydroxyl and in their trimethylsilyl ether forms. First, the derivatization procedure was verified through the identification of the trimethylsilyl ethers formed on the basis of their mass spectra and optimized to obtain quantitative reaction. The optimized procedure was applied to the trimethylsilylation of racemic mixtures of various hydroxyl compounds. The silylation was found to be highly effective in the improvement of the separation of the individual enantiomers. The major advantages of the derivatization process can be summarized as: (i) excellent baseline separation of the enantiomers of the silyl ethers was achieved in contrast to the parent OH-containing compounds, (ii) the sensitivity of detection highly increased, (iii) the separations do not show any significant concentration dependence and finally (iv) the analysis time needed decreased significantly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467521
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  • 20
    Electronic Resource
    Electronic Resource
    Data correlation in on-line solid-phase extraction-gas chromatography-atomic emission/mass spectrometric detection of unknown microcontaminants (1998)
    Springer
    Chromatographia 48 (1998), S. 273-283 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Atomic emission and MS detection ; Solid-phase extraction ; Aqueous samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure is described for the (non-target) screening of hetero-atom-containing compounds in tap and waste water by correlating data obtained by gas chromatography (GC) using atomic emission (AED) and mass selective (MS) detection. Solid-phase extraction (SPE) was coupled on-line to both GC systems to enable the determination of microcontaminants at the 0.02–1 μg L−1 level in 7–50 mL of aqueous sample. The screening was limited to compounds present in at least one heteroatom-selective GC-AED trace above a predetermined concentration level. These compounds were identified by their partial formulae (AED) and the corresponding mass spectra, which were obtained from the GC-MS chromatogram via the retention index concept. The potential of the approach was demonstrated by the identification of target compounds as well as all unknowns present in tap and waste water above the predetermined threshold of 0.05 μg L−1 (tap water) or 0.5 μg L−1 (waste water).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467683
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  • 21
    Electronic Resource
    Electronic Resource
    Crown ether capped cyclodextrin used as stationary phase for capillary gas chromatography (1998)
    Springer
    Chromatographia 48 (1998), S. 817-822 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Crown ether capped cyclodextrin ; Chiral separations ; Isomer separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The solution of a new synthesized compound, mono-6-(1'-benzo-aza-15-crown-5)-2, 3, 6- permethyl-β-cyclodextrin, in the moderately polar polysiloxane OV-1701 was coated onto fused silica capillary column. The chromatographic characteristics including column efficiency, polarity and selectivity were studied. Excellent selectivity for the separation of enantiomers and positional isomers was obtained. The results show that the combined effect between the special caves of β-cyclodextrin and crown ether plays a significant role in the separation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467654
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  • 22
    Electronic Resource
    Electronic Resource
    Gas chromatography with UV-vis molecular absorption spectrometry detection: Data acquisition and treatment when using a diode-array spectrophotometer (1998)
    Springer
    Chromatographia 48 (1998), S. 535-541 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; UV-Vis detection ; Gas phase absorption spectrometry ; Alcohols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This article describes a theoretical/practical study of the parameters which affect the chromatograms obtained when using a molecular diode-array spectrometer as the detector in gas chromatography. The objective is to offer some rules which permit the identification of the optimum signal/noise relation. To achieve this, we study the effect of the different parameters which affect the noise and how to reduce their impact, as well as alternatives for increasing the signal. All the options tested can be applied by correctly programming the spectrometer with BASIC programs, within reach of any use who has even a small understanding of programming. Finally, we consider the effect that the selection of the acquisition conditions may have on the chromatographic resolution. All the studies are carried out using a mixture of alcohols and phenols.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466646
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  • 23
    Electronic Resource
    Electronic Resource
    Synthesis of a new liquid crystal, 4-[(4-chlorobenzyl)oxy]-4′-cyanoazobenzene and its use as stationary phase in gas-chromatography (1998)
    Springer
    Chromatographia 48 (1998), S. 427-430 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Liquid crystal stationary phase ; Packed columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation ofm-, p-, o- xylenes andm-, p- ethyltoluenes was studied on a packed column with 2,5% of 4-[(4-chlorobenzyl)oxy]-4′-cyanoazobenzene (CBOCA) on Chromosorb W HP 100–120 mesh. The synthesis and study of the mesomorphic behaviour of CBOCA are presented. Temperature range for the separation ofm-, p-, o- xylenes (in this order of elution) is 125–85°C, at cooling. The best separation was achieved at about 90°C. The separation temperature domain ofm-ethyltoluene fromp- ethyltoluene is 160–85°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467715
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  • 24
    Electronic Resource
    Electronic Resource
    Derivatization of aromatic amines with bromine for improved gas chromatographic determination (1998)
    Springer
    Chromatographia 48 (1998), S. 436-442 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Water analysis ; Derivatization with bromine ; Aromatic amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For improved determination of aromatic amines by gas chromatography and detection with an electron capture detector (GC-ECD) a derivatization method based on the bromination of the aromatic ring in an acetic acid medium was developed. In general, all free ortho and para-positions relative to the amino group undergo electrophilic substitution. Separation of at least 30 compounds in a single chromatographic run in 30 min is possible. With this method, 56 aromatic amines were studied and only in 6 cases were no derivatives obtained. Quantitation limits determined from calibration data are 1.2–40 μg L−1 for a 100 mL sample and an injection volume of 1 μL. Previous experiments suggest that both sample and injection volume may be increased to lower the quantitation limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467717
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  • 25
    Electronic Resource
    Electronic Resource
    Effect of organic matter content in the trace analysis of triazines in various types of soils with GC-NPD (1998)
    Springer
    Chromatographia 48 (1998), S. 450-456 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Soil samples ; Microwave-assisted solvent extraction ; Nitrogen detection ; Triazine herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Recent work demonstrated that the combination of microwave assisted solvent extraction (MASE) and capillary gas chromatography with selective nitrogen detection (GC-NPD) is a viable approach for the efficient determination of triazine herbicides in soils. However, for soils with a high organic matter content or the injection of more concentrated extracts to obtain lower LOD's the performance of gas chromatographic analysis of uncleaned extracts is hampered. This results in both a decrease of the chromatographic response of analytes and a decrease in the life time of the column due to coextracted matrix substances. The effect of various types of soils on the chromatographic analysis of triazine herbicides was studied. It appeared that for the investigated samples with an organic matter content below 5% processing of uncleaned extracts is possible. Samples with a higher organic matter content required a cleanup step. A rapid procedure on 100 mg silica cartridges has been developed using solvents compatible with the MASE extracts and the instrumental analysis. Beside the testing with different standard soils, about 120 samples of an ongoing monitoring program involving three different types of soil (organic matter content: 3–37%) were analysed. The selected compounds atrazine, desethylatrazine, desisopropyl-atrazine and simazine could be assayed in the various soil types to a level of at least 2 μg kg−1. For soil samples with a high organic matter content (〉5%), the rapid cleanup procedure allowed the trace analysis of the triazines and considerably increased the life time of the capillary column. Recoveries at levels from 2 to 50 μg kg−1 ranged from 70 to 100% with RSDs ranging from 5.1 to 9.5%. Confirmation of positive samples was carried out by gas chromatography mass spectrometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467719
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  • 26
    Electronic Resource
    Electronic Resource
    Identification and semi-quantitative determination of a migration contaminant from beverage carton packages into mineral water by on-line solid phase extraction gas chromatography-mass spectrometry (SPE-GC-MS) (1998)
    Springer
    Chromatographia 48 (1998), S. 581-583 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; On-line SPE-GC-MS ; Beverage carton packages ; Contaminant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An unknown migration contaminant was found in a number of mineral water samples contained in beverage carton packages. This compound was isolated by a fully automatic solid phase extraction system and identified by means of GC-MS as 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD) [126-86-3], which is used as a surfactant in water-based printing inks and migrates during the production of the beverage carton material into the inner polyethylene film and subsequently into the product. The determined concentrations of TMDD ranged up to more than 50 μg L−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466653
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  • 27
    Electronic Resource
    Electronic Resource
    Direct solid-phase microextraction combined with gas and liquid chromatography for the determination of lidocaine in human urine (1998)
    Springer
    Chromatographia 47 (1998), S. 678-684 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Solid-phase microextraction ; Local anaesthetic lidocaine ; Optimisation of extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Solid-phase microextraction (SPME) has been combined with gas chromatography (GC) and liquid chromatography (LC) for the determination of lidocaine in human urine. A polydimethylsiloxane (PDMS) coated fibre was directly immersed into buffered urine. Extraction conditions such as time, pH, ionic strength, temperature, and agitation were optimised. The extracted lidocaine was thermally desorbed in a split/splitless injector for analysis with a GC-FID system or desorbed with liquid in a specially designed SPME-LC interface for analysis with an LC-UV system. After optimisation the method developed was evaluated and validated. Extraction yields of 22% were obtained in about 45 min. The reproducibility of the method is 〈5% (relative standard deviation). For five-times diluted urine, linear ranges were found from 5–1000 and 25–1000 ng·mL−1 for SPME-GC and SPME-LC, with detection limits of 5 ng·mL−1 for SPME-GC and 25 ng·mL−1 for SPME-LC. SPME can be used as a simple sample pretreatment method for the determination of lidocaine in urine by GC and LC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467453
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  • 28
    Electronic Resource
    Electronic Resource
    Investigation on five novel substituted β-cyclodextrins used as GC stationary phases (1998)
    Springer
    Chromatographia 47 (1998), S. 557-564 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phases ; β-Cyclodextrin derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Five β-cyclodextrin derivatives, heptakis[2,6-di-O-pentyl-3-O-(4-nitrobenzyl)-β-CD (CD-I), heptakis [2,6-di-O-pentyl-3-O-(5-hexenyl)]-β-CD (CD-II), heptakis-(2, 6-di-O-cinnamyl-3-O-methyl)-β-CD (CD-III), heptakis-(2, 6-di-O-cinnamyl-3-O-acetyl)-β-CD (CD-IV) and heptakis(2, 6-di-O-cinnamyl-3-O-trifluoroacetyl)-β-CD (CD-V), were synthesized and coated on fused-silica capillary coluns. Their chromatographic characteristics were tested and compared with heptakis (2,3,6-tri-O-pentyl)-β-CD (CD-VI) and heptakis (2,6-di-O-pentyl-3-O-trifluoroacetyl)-β-CD (CD-VII). It was found that the size, polarity, and aromatic property of the substituted group at the 3-position of heptakis (2,6-di-O-pentyl)-β-cyclodextrins greatly influenced their chromatographic properties and separation ability. The introduction of aromatic group or a group containing a double-bond may bring π-π interactions between the host and guest molecules, and therefore increased the separation ability of the β-CDs for substituted benzene isomers. Introduction of cinnamyl groups in to the 2,6-3-position of β-CD has a significant effect on the chromatographic properties of the stationary phases(CD-III-CD-V).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467495
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  • 29
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    Electronic Resource
    Determination of heats of vaporization and gibbs free energies of alkylbenzenes on GC stationary phases of different polarity (1998)
    Springer
    Chromatographia 48 (1998), S. 89-94 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Heats of vaporization ; Gibbs free energies ; Kováts retention indices ; Alkylbenzenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In our paper we propose a new method for the determination of heats of vaporization (ΔH vap(i)) and the Gibbs free energies of vaporization (Δμp(i)) for individually selected alkylbenzenes, chromatographed on stationary phases of low and medium polarity. The method is based on a new thermodynamic description of the Kováts retention index (I (i)) making use of Trouton's rule. In fact, we attribute physical significance to two empirical relationships, well known from the literature. We can describe thermodynamically the magnitude ofI (i) using two relations, each of them potentially useful for further determination of δH vap(i) and Δμp(i). A comparison was made of the results obtained with the use of our new approach and of those already existing in the literature attained in a completely different way. The comparison suggests that the calculated δH vap(i) and Δμp(i) values are thermodynamically acceptable and hence correct, and the data suit into the series of similar values determined on stationary phases of different polarity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467523
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  • 30
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    Electronic Resource
    Separation of polychlorinated biphenyls from chlorinated pesticides using aminopropyl bonded-phase cartridge and determination by GC-ECD (1998)
    Springer
    Chromatographia 48 (1998), S. 293-298 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase extraction ; Polychlorobiphenyls ; Clorinated pesticides ; Organochlorine separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples is carried out after adsorption from a 25–500 mL sample, on a cartridge containing 100 mg aminopropyl-bonded porous silica. The clean-up step in which the PCBs and chlorinated pesticides are separated in different eluates is achieved by passing 25 mL of 40% aqueous methanol through the NH2 Sep-Pak cartridge. The PCBs are desorbed with 500 μL ethylacetate, which is concentrated and analysis by GC-ECD. The average recovery, at 1 ppb is 〉97% with a standard deviation 〈2. The limits of detection are 0.1 ng μL−1 and 5 pg μL−1 respectively for Cl3-PCB and Cl8-PCB congeners. In the separation of PCBs from the chlorinated pesticides tested in this work, only the Aldrin is adsorbed for 60% with the PCBs by the NH2 Sep-Pak cartridge. The method described is rapid, simple and reproducible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467685
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  • 31
    Electronic Resource
    Electronic Resource
    Characterisation of GC stationary phases in multilinear retention model (1998)
    Springer
    Chromatographia 48 (1998), S. 728-738 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phases ; Prototypical phases ; Retention model ; Retention value ; Dipolarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Stationary phases are characterised in a multilinear retention model by retention data of a set of selected prototypical substances. Prototypical stationary phases confirm the application of prototypical substances in the retention model. For comparison, 27 stationary phases are characterized with solute descriptors of the solvation model. New adjusted substance factors are calculated for 33 selected compounds for a new characterization of GC stationary phases in the extended retention model with retention values, calculated from retention indices and b-values of the n-alkane equation. Substance dipolarityD N-factors are separated from πN, the adjusted dipolarity-polarisability. New substance factors give satisfying correlation results and new explanatory factors as phase descriptors for 27 stationary phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467640
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  • 32
    Electronic Resource
    Electronic Resource
    Precision of milk fat quantitation in mixed fats by analysis of butyric acid (1998)
    Springer
    Chromatographia 48 (1998), S. 758-762 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Butyric acid ; Milk fat content ; Mixed fats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Quantitation of the milk fat content in mixed fats is of interest in food analysis. It can be achieved by calculation from the butyric acid (C4) content in the mixed fat and a mean C4 content for pure milk fats. Alternatively, instead of applying a C4 mean value, the C4 content in the actual milk fat can be used if this reference sample is available. A recently improved analytical method based on gas chromatography of butyric acid methyl ester using an internal standard has been applied to determine the milk fat content in mixtures with beef tallow, lard, soybean oil, olive oil, sunflower oil, palm kernel oil and palm oil ranging from 1 to 90% milk fat content. Within the whole range of mixtures, mean absolute deviations between the determined and the actual milk fat content were below 0.5% and the maximum absolute deviation was not more than 1.0% when using the reference sample. The overall mean absolute deviation was 0.04% for milk fat contents of 1 to 10% and 0.28% for milk fat contents of 10 to 90%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467644
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  • 33
    Electronic Resource
    Electronic Resource
    Determination of acids in Brazilian sugar cane spirits and other alcoholic beverages by HRGC-SPE (1998)
    Springer
    Chromatographia 48 (1998), S. 751-757 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase extraction ; Brazilian sugar cane spirit ; Lower fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method for the analysis of seventeen acids in a water/ethanol matrix is described. The diluted samples were first concentrated by solid phase extraction. Nonanoic acid was the internal standard. A good separation profile was obtained for all compounds, including the isomers: n and iso-butyric acids, n and isovaleric acids and n and iso-caproic acids. The method is fast, sensitive (20–30 μg L−1) and has a good reproducibility (4–7 %). The recovery was in the range of 94%–116% for the medium chain acids (C7-C16). This method allowed the identification of fourteen acids in caninhas and other spirits. The total acid content and the profile of the exportation type caninhas are similar to the ones obtained for several international beverages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467643
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  • 34
    Electronic Resource
    Electronic Resource
    Gas chromatography with UV-vis molecular absorption spectrometry detection: Increasing sensitivity of the determination of alcohols and phenols by derivatization (1998)
    Springer
    Chromatographia 48 (1998), S. 542-547 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; UV-Vis detection ; Gas phase absorption spectrometry ; Derivatization ; Alcohols and phenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is proposed for the determination of alcohols and phenols based on their derivatization to benzoates and gas chromatography-gas phase molecular absorption spectrometry. All parameters affecting the derivatization reaction, such as the solvent, basic medium, benzoyl chloride and stirring time, were optimized. Chromatographic and instrumental conditions were also studied. Finally, a calibration study was performed and the results were compared to that obtained by the direct determination of the compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466647
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  • 35
    Electronic Resource
    Electronic Resource
    Gas chromatography analysis of organophosphorous pesticides in plant samples (1998)
    Springer
    Chromatographia 48 (1998), S. 156-157 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gel permeation chromatography ; Organophosphorous pesticides ; Plant samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The work presents a GC method for the determination of six organophosphorous pesticide residues in cabbage. Chopped cabbage was blended with acetone, then extracted with the mixture of n-hexane:methylene chloride (1:1). The extract was purified on a GPC column packed with BioBeads SX-3 gel. The pesticides were eluted with the mixture of methylene chloride:cyclohexane (1:1) at the flow rate of 0.5 mL min−1. After concentrating the extract was analysed by GC. Nearly 100 samples of cabbage were analysed; trace residues of dimethoate (about 0.05 ppm) were found in 10 samples. The average recoveries of the pesticides were above 80% with a relative standard deviation mostly less than 10%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467534
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  • 36
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    Electronic Resource
    Gas chromatographic determination of major sterols in edible oils and fats using solid-phase extraction in sample preparation (1998)
    Springer
    Chromatographia 48 (1998), S. 745-750 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase extraction ; Rapeseed oil ; Sterols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A capillary gas chromatographic method is described for the determination of major plant sterols and cholesterol in edible oils and fats. In the sample preparation procedure reversed-phase, solid-phase extraction with C18 adsorbent was used to extract the unsaponifiable matter and for sample cleanup after saponification. Sterols were quantitated as their trimethylsilylether derivatives using an internal standard method (betulin). The method was validated by recovery tests and analysis of two reference materials representing vegetable oil mixture and milk fat matrices. Average recoveries of spiked cholesterol and cholesterol acetate in rapeseed oil were 103±4% (n=12) and 101±3% (n=10), respectively. The sterol values determined in the reference materials were found to be in a good agreement with their given certified or indicative values. Applied to edible oils and fats, plant sterols and cholesterol at levels〉20 mg kg−1 could be accuratively quantitated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467642
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  • 37
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    Electronic Resource
    Headspace gas chromatography analysis of toxic contaminants in ethoxylated alcohols and alkylamines (1998)
    Springer
    Chromatographia 48 (1998), S. 299-304 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace sampling ; Ethoxylated alcohols ; Ethoxylated alkylamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Headspace-gas chromatography was used to determine the contents of toxic 1,4-dioxane, ethylene oxide and ethylene glycol in ethoxylated alcohols and alkylamines, and in commercial cosmetics and washing products. A Permaphase PEG capillary column was used for the determination of 1,4-dioxane and ethylene oxide and a DB-17 column for ethylene glycol determination. Dimethylformamide was used as the solvent in the determination of 1,4-dioxane and ethylene oxide, and undecanol in the case of ethylene glycol. The detection limits for ethylene oxide, 1,4-dioxane and ethylene glycol are 1,2 and 10 μg·g−1, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467686
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  • 38
    Electronic Resource
    Electronic Resource
    Calix[4]arene derivatives as stationary phases for capillary gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 689-694 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phases ; Calix[4]arene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two new kinds of calix[4]arene derivatives, 5,11,17,23-tetra-tert-butyl-25,27-bis(isopropylcarbamoyl-methoxy)-26,28-diundecenyloxy calix[4]arene (C[4]A) and 25,27-dibutoxy-5,11,17,23-tetra-tert-butyl-26,28-diundecenyloxy calix[4]arene (C[4]B), have been synthesized for use as stationary phases in capillary gas chromatography with OV1701. These stationary phases demonstrate high column efficiencies, wide operating temperature ranges, good thermal stability and excellent selectivity for aromatic isomers, especially phenol compounds. Their inclusion properties are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467455
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  • 39
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    Electronic Resource
    Comparison of methods for prediction of the retention data of aromatic hydrocarbons on UCON LB 550X and on polydimethylsiloxane (1998)
    Springer
    Chromatographia 47 (1998), S. 721-723 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Correlation equation ; Alkylbenzenes ; Naphthalenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A detailed statistical analysis is presented for comparing the validity of selected literature-recommended equations with the unified retention index concept for calculating the retention indexes of alkylbenzenes on UCON LB 550X and naphthalenes on polydimethylsiloxane. Comparison with literature sources shows that the unified retention index provides the smallest residual error for a set of aromatic hydrocarbons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467460
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  • 40
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    Electronic Resource
    Quantitative analysis of residual synthetic polystyrene adsorbent in drugs by curie-point pyrolysis gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 203-208 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Pyrolysis GC ; Residual polystyrene ; Streptomycin ; Vitamin B1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Residual synthetic adsorbent, cross-linked polystyrene, used in drug purification has been analyzed quantitatively by Curie-point pyrolysis gas chromatography. The peaks of intact polystyrene adsorbent in the pyrogram were used as key peaks for quantitative measurement of residues of the adsorbent in vitamin B1 and streptomycin sulfate. It was shown that them-ethylstyrene orp-ethylstyrene peaks in the pyrolyzates were suitable for determination of polystyrene adsorbent content. The levels of residual adsorbent in the drugs were found to be 〈0.1 %, the value stipulated by the International Conference on Harmonization (ICH). In quantitative evaluation of an adsorbent content of 0.1 % the precision was 3.6 % and 2.7 % for vitamin B1 and streptomycin sulfate, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466582
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  • 41
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    Electronic Resource
    Retention indices of alkenes and the corresponding epoxides on a capillary column coated with cyanopropyl methyl silicone phase (1998)
    Springer
    Chromatographia 47 (1998), S. 230-233 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Alkenes ; Epoxides ; Retention index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention indices or five 1-alkenes, seven branched alkenes and five cycloalkenes and the corresponding epoxides were determined at two temperatures on a fused-silica capillary column coated with cyanopropyl methyl siloxane to interpret their chromatographic behaviour. The standard deviation was 0.2 index units.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466587
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  • 42
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    Electronic Resource
    Determination of safrole in differentAsarum species by headspace gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 685-688 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace sampling ; Safrole ; Asarum species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The development of a headspace GC method (HS-GC) to determine the safrole content in differentAsarum species from China and Europe, using eugenol as internal standard, is presented in this paper. The best results could be achieved by thermostating the samples at 100°C for 30.0 min, adding 10 μL of water to each sample. Optimum pressurisation and injection time showed to be 3.0 min and 12 s, respectively. GC separation was performed on an SE-54 column. The HS-GC results for safrole were in good agreement with those obtained by direct GC analysis of the dichloromethane (DCM) plant extracts. The investigated Asarum samples showed great deviations concerning the safrole content even within the sameAsarum species, e.g.Asarum himalaicum from Sichuan contained 0.0051% of this compound, the same species from the province of Hebei 0.53%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467454
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    Gas chromatographic analysis of phthalate esters in plastic toys (1998)
    Springer
    Chromatographia 47 (1998), S. 724-726 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Phthalate esters ; PVC ; Plastic toys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the analysis of 10 phthalate esters in plastic toys is described. The samples are soxhlet extracted in dichloromethane and phthalate esters in the extract are analysed by GC. Detection limits of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, bis(2-ethylhexyl) phthalate, di-n-octyl phathalate, di-n-nonyl phthalate, benzyl butyl phthalate and benzyl octyl phthalate were approximately 5 ppm. The detection limits of diisononyl phthalate and diisodecyl phthalate, which are mixtures of several isomers, were approximately 200ppm. Analysis of 17 plastic toys revealed that only PVC-toys contained phthalate esters. Bis(2-ethylhexyl) phthalate, diisononyl phthalate and diisodecyl phthalate in concentrations up to 40% were present in the PVC-toys.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467461
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  • 44
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    Electronic Resource
    Analysis of cyanide in blood by headspace solid-phase microextraction (SPME) and capillary gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 209-214 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid-phase microextraction ; Headspace sampling ; Cyanide in blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Cyanide can be extracted from whole blood samples by headspace solid-phase microextraction (SPME) with a Carbowax/divinylbenzene-coated fiber. During heating a vial of a whole blood sample containing cyanide and acetonitrile as internal standard (IS) at 50°C in the presence of Na2SO4, a Carbowax/divinylbenzene-coated SPME fiber was exposed in the headspace of the vial for 45 min to allow adsorption of cyanide and IS. The fiber needle was then injected into a capillary gas chromatography (GC) instrument equipped with nitrogen-phosphorus detection. The headspace SPME-GC with a Supel-Q PLOT fused silica capillary column gave large peaks for cyanide and IS; almost no interfering peaks appeared. Recoveries of cyanide dnd IS from human whole blood were 3.02–4.06% and 0.21%, respectively. The calibration curve for cyanide added to human blood showed excellent linearity in the range of 0.04–4.0 μg mL−1; the detection limit was about 0.02 μg mL−1. The coefficients of intra-day and inter-day variation were not greater than 7.1 and 9.2%. Good correlation (r 2=0.999) was found between the present SPME-GC method and the conventional microdiffusion colorimetric method. Data on determination of cyanide in rat blood after intraperitoneal administration are also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466583
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  • 45
    Electronic Resource
    Electronic Resource
    Synergistic effects in mixed gas chromatographic stationary phases consisting of dibenzo-18-crown-6 and MPBHpB (1998)
    Springer
    Chromatographia 47 (1998), S. 575-578 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Mixed stationary phases ; Dibenzo-18-crown-6 ether ; MPBHpB ; Synergistic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The synergistic effect is investigated in mixed gas chromatographic stationary phases containing dibenzo-18-crown-6 +MPBHpB [o-methyl-p-phenylene-bis-(p-heptoxy benzoate)], [o-methyl-p-phenylene-bis-(p-heptoxy benzoate)], with benzene/cyclohexane, cyclokexanes, phenols, alcohols and aniline derivatives as sample compounds pairs. Some of the separations reveal positive or negative synergistic effect. This effect depends on the temperature, the mixing ratio and the linear velocity of the carrier gas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467498
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  • 46
    Electronic Resource
    Electronic Resource
    Sulfuric acid pretreatment for the simultaneous GC screening of organochlorine and organophosphorus pesticides in herbal essential oils (1998)
    Springer
    Chromatographia 47 (1998), S. 587-592 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Organochlorine and organophosphorus pesticides ; Herbal medicine ; Essential oils ; Sulfuric acid treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and new clean-up method utilizing sulfuric acid treatment is demonstrated to identify and quantify the level of organochlorine (OC) and organophosphorus (OP) pesticide residue concentrations in herbal essential oils by gas chromatography (GC). Essential oils fortified with pesticides, that are extracted from herbs by steam distillation are partitioned with 65% acetonitrile/water(v/v) and treated with sulfuric acid at different reaction times and sulfuric acid concentrations. Optimal conditions, to avoid interference from essential oils in gas chromatographic analysis, is 17% (v/v) of a mixed phase ratio of sulfuric acid to organic solvent (hexane/ethyl ether=9∶1, v/v) and a reaction time of 30s. The response of the flame ionization detector (FID) is linear for all pesticides determined. Recovery of pesticides from fortified herbs studied are in the range of 75% to 111% (RSD, 4% to 11%) for OC, and 72% to 116% (RSD, 2% to 11%) for OP. Although sulfuric acid treatment destroys carbamate and some organophosphorus pesticides, this method has efficiently reduced matrix interference and provides a rapid, economical clean-up method with excellent linear data having low coefficients of variation for the GC analyses of BHC isomers, DDD, DDE, DDT, chlorothalonil, chloropyrifos, tetradifon, fenitrothion, malathion, and parathion in matrices of herbal essential oils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467500
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  • 47
    Electronic Resource
    Electronic Resource
    Enantiomeric separation of unusual secondary aromatic amino acids (1998)
    Springer
    Chromatographia 48 (1998), S. 53-58 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Enantiomeric separation ; Chiral derivatization ; Unusual secondary aromatic amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatographic and gas chromatographic methods were developed for the separation of unusual secondary aromatic amino acids. Amino acids containing 1,2,3,4-tetrahydroisoquinoline, 1,2,3,4-tetrahydronorharmane-1-carboxylic acid and 1,2,3,4-tetrahydro-3-carboxy-2-carboline moieties were synthetized in racemic or chiral forms. The high-performance liquid chromatography was carried out either on a teicoplanin-containing chiral stationary phase or on an achiral C18 column. In the latter case the diastereomers of the amino acids formed by precolumn derivatization with the chiral reagents 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate or 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide were separated. The gas chromatographic analyses were based on separation on a Chirasil-L-Val column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467516
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  • 48
    Electronic Resource
    Electronic Resource
    Urinary steroid analysis of women with effluvium (1998)
    Springer
    Chromatographia 48 (1998), S. 86-88 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase extraction ; Methoxime-silyl derivate ; Urinary steroids ; Women with effluvium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Urinary steroid metabolites were measured by capillary gas chromatography in 25 women (aged 33.3±12.0 years) with effluvium and 16 control healthy laboratory workers women (aged 34.6±8.4 years). There was significant elevation in the level of a number of steroids and steroid metabolites. The elevation of most steroid metabolites refers to the increased steroid secretion of the adrenal and the high cortisol metabolites levels may be do to stress in some of the patients with effluvium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467522
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  • 49
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    Electronic Resource
    Enantioseparation of the compounds of technical toxaphene (CTTs) on 35% heptakis (6-O-tert-butyldimethylsilyl-2,3-di-O-Methyl)-β-cyclodextrin in OV1701 (1998)
    Springer
    Chromatographia 47 (1998), S. 565-569 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Chiral stationary phases ; Enantioseparation ; Toxaphene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the enantiomers of the compounds of technical toxaphene (CTTs) on heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin (β-TBDM) has been studied by gas chromatography with electron-capture detection (GC-ECD). Enantiomers of eight of the nine CTTs under investigation were separated on this chiral stationary phase. Separations of the enantioners of CTTs have hitherto been achieved ontert-butyldimethylsilylated β-cyclodextrin (β-BSCD). The chiral resolution values and separation factors of the CTTs on β-TBDM have been compared with those obtained on β-BSCD. Although several components coeluted, enantioselective determination of three CTTs was possible in an extract of seal blubber. For each CTT the first-eluting enantiomer was enantioenriched. Enantioselective accumulation of2-endo, 3-exo,5-endo,6-exo,-8,8,9,10-octachlorobornane (B8-1412) in biota has been established for the first time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467496
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  • 50
    Electronic Resource
    Electronic Resource
    Determination of triacylglycerol composition of idiazabal cheese (1998)
    Springer
    Chromatographia 47 (1998), S. 579-586 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Ewe's cheese ; Triacylglycerols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Triacylglycerols from Idiazabal cheese fat were analysed by high-performance liquid chromatography (LC) with a non-linear gradient of acetone in acetonitrile and a light-scattering detector. Molecular species of triacylglycerols were predicted by a simple and a multiple linear regression analysis of logk of the LC peaks and molecular variables such as equivalent carbon number of the possible triacylglycerol, chain length and number of double bonds of each fatty acid of the triacylglycerol. Predicted results were confirmed by gas chromatographic analysis of the fatty acids in the LC peaks. The main triacylglycerols of Idiazabal cheese fat contained butyric acid, butyroyl-dipalmitin, butyroyl-myristoyl-palmitin and butyroyl-palmitoyl-olein. The most abundant triacylglycerols were those with even partition numbers of 36, 34 and 38.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467499
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  • 51
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    Electronic Resource
    Charge-transfer interactions between nucleophilic compounds and chromatographic packings containing chemically bonded Cu(II) complexes (1998)
    Springer
    Chromatographia 48 (1998), S. 284-292 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Metal complexes ; Chemically bonded phases ; Thermodynamic parameters ; Specific interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Results are presented of studies of packings containing copper (II) acetylacetonate (acac), hexafluoroacetylacetonate (hfac), and chloride, chemically bonded via β-dik-etonate groups. The retention parameters retention factor (k) specific retention volume (V g), and molecular retention index (M e) were measured and used to calculate the thermodynamic parameters free energy of adsorption (ΔG a) heat of adsorption (−ΔH a), and entropy of adsorption (ΔS a). These parameters enable, characterization of specific interactions between aromatic and cyclic hydrocarbons, ethers and thioethers and metal complexes chemically bonded, to a silica surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467684
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  • 52
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    Electronic Resource
    Simple and sensitive detection of phencyclidine in body fluids by gas chromatography with surface ionization detection (1996)
    Springer
    International journal of legal medicine 108 (1996), S. 244-247 
    Details
    ISSN: 1437-1596
    Keywords: Phencyclidine ; Pethidine ; Gas chromatography ; Surface ionization detection ; Sep-Pak C18 cartridges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Notes: Abstract Phencyclidine (PCP) can be detected in body fluids with very high sensitivity by gas chromatography (GC) with surface ionization detection (SID) using pethidine as internal standard. PCP was extracted with Sep-Pak C18 cartridges from whole blood and urine samples, which gave clean extracts. The calibration curve for spiked whole blood was linear in the range 1.25–20 ng/ml. The detection limit of PCP was approximately 15 pg on-column (0.75 ng/ml sample), which was much lower than by GC-nitrogen phosphorus detection. The recovery of PCP and pethidine from spiked whole blood or urine samples was above 85%. This method seems very useful for the determination of PCP in forensic and clinical toxicology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01369818
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  • 53
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    Electronic Resource
    Encoding of plant odours by receptor neurons in the pine weevil (Hylobius abietis) studied by linked gas chromatography-electrophysiology (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 331-344 
    Details
    ISSN: 1432-1351
    Keywords: Hylobius abietis ; Olfaction ; Plant odours ; Receptor neuron responses ; Gas chromatography ; Electrophysiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Receptor neuron responses to plant volatiles, trapped by head-space procedures, were examined in the pine weevil Hylobius abietis, using gas chromatography linked with electrophysiological recordings from single neurons. Seventy-two receptor neurons were tested 173 times for various plant volatile mixtures, either via a polar or a non-polar column. 1) All responses appeared as increased firing rates which followed the concentration profiles of the GC-eluted compounds. 2) The neurons were classified separately for the two column types in 17 and 19 groups respectively, according to the compounds they responded to. It suggests that the plant odour information is encoded by a large, but limited number of receptor neuron types. 3) Most neurons responded to a limited number of compounds (1–5) and showed a marked best response to one of them, whereas additional responses to several other components which seems to be structurally similar, was recorded for some neurons. It suggests that the plant odour receptor neurons are rather narrowly than broadly tuned, and that each neuron is specialized for receiving information about one or a few related compounds. 4) Most neurons responded to monoterpenes, whereas the other neurons responded to compounds of other categories. 5) Both major and minor plant volatile components activated specifically receptor neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194987
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  • 54
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    Electronic Resource
    On-line monitoring of benzene air concentrations while driving in traffic by means of isotopic dilution gas chromatography/mass spectrometry (1996)
    Springer
    International archives of occupational and environmental health 68 (1996), S. 262-267 
    Details
    ISSN: 1432-1246
    Keywords: Gas chromatography ; Mass spectrometry ; Benzene ; Air pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract There is no shortage of information about the average benzene concentrations in urban air, but there is very little about microenvironmental exposure, such as in-vehicle concentrations while driving in various traffic conditions, while refuelling, or while in a parking garage. The main reason for this lack of data is that no analytical instrumentation has been available to measure on-line trace amounts of benzene in such situations. We have recently proposed a highly accurate, high-speed cryofocusing gas chromatography/mass spectrometry (GC/MS) system for monitoring benzene concentrations in air. Accuracy of the analytical data is achieved by enrichment of the air sample before trapping, with a stable isotope permeation tube system. The same principles have been applied to a new instrument, specifically designed for operation on an electric vehicle (Ducato Elettra, Fiat). The zero emission vehicle and the fully transportable, battery-operated GC/MS system provide a unique possibility of monitoring benzene exposure in real everyday situations such as while driving, refuelling, or repairing a car. All power consumptions have been reduced so as to achieve a battery-operated GC/MS system. Liquid nitrogen cryofocusing has been replaced by a packed, inductively heated, graphitized charcoal microtrap. The instrument has been mounted on shock absorbers and installed in the van. The whole system has been tested in both fixed and mobile conditions. The maximum monitoring period without external power supply is 6 h. The full analytical cycle is 4 min, allowing close to real-time monitoring, and the minimum detectable level is 1 μg/m3 for benzene. In-vehicle monitoring showed that, when recirculation was off and ventilation on, i.e., air from outside the vehicle was blown inside, concentrations varied widely in different driving conditions: moving from a parking lot into normal traffic on an urban traffic condition roadway yielded an increase in benzene concentration from 17 to 62.3 μg/m3 even if the actual distance was small. A larger increase was observed when a car was left with the engine running at a distance 2 m from the zero emission vehicle: We measured an increment of benzene concentrations from 15.2 to 174.4 μg/m3 with a car equipped with a catalytic converter, and from 19.1 to 386.3 μg/m3 with a car without such a converter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381438
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  • 55
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    Electronic Resource
    The stability of selected herbicides preconcentrated from estuarine river waters on solid-phase extraction disks (1996)
    Springer
    Chromatographia 42 (1996), S. 72-76 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Estuarine waters ; Solid-phase extraction ; Triazines, alachlor, metolachlor ; Nitrogen phosphorus detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The stability of atrazine, simazine, alachlor, metolachlor, and deethylatrazine on C18 Empore disks has been determined. Estuarine water (100 mL) spiked at 3 μg L−1 with the target pesticide mixture was preconcentrated on the disks; the disks were then stored at −20°C, 4°C, and at room temperature for periods up to three months and were analyzed by gas chromatography with nitrogen-phosphorus detection. Complete recovery was observed after storage at −20°C throughout the period of the study. Losses up to maximum of 10% were observed after storage at 4°C. Higher losses (up to 24% for alachlor) occurred only at room temperature; the coefficient of variation for these determinations (8–11%) was also higher than that for the others (3–5%). The stability of the pesticides was dependent on the water matrix, on storage temperature, and on properties such as vapor pressure and water solubility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271058
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  • 56
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    Electronic Resource
    Contribution to the unified retention data of hydrocarbons on squalane (1996)
    Springer
    Chromatographia 42 (1996), S. 660-664 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Unified retention data ; Alkanes, alkenes, naphthenes and aromatics ; Squalane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatographic, unified retention data of 120 hydrocarbons including: alkanes, alkenes, alkynes, alkylcycloalkanes, alkylcycloalkenes, aromatics and dienes on squalane stacionary phases are given. These values agree well with the corresponding experimental values used in the statistical treatment of the experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267698
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  • 57
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    Electronic Resource
    Structure-retention relationships in the gas chromatography of N,N-dialkylhydrazones (1996)
    Springer
    Chromatographia 42 (1996), S. 653-659 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Dialkylhydrazones ; Kováts retention indices ; Structure-retention relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary N,N-Dialkylhydrazones [DAHs; R1R2C=1N-2N(R3)2] were prepared and their Kováts retention indices determined on 100% dimethylpolysiloxane (HP-1) and 5% diphenyl and 95% dimethylpolysiloxane (HP-5) stationary phases. The physico-chemical and retention behaviour of the DAHs depend greatly on whether R2=H or an alkyl group. A similar difference is observed in the alkane and oxo homomorphic factors of DAHs formed from aldehydes or ketones. The difference is explained on the basis of NMR and quantum-chemical results by intramolecular interactions between R2 and the lone pair of the2N atom. A single linear equation is suitable for prediction of retention indices if parameters are introduced representing resonance structure (bond angle and electron density) besidesI oxo or the van der Waals' surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267697
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  • 58
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    Electronic Resource
    Temperature programmed gas chromatography of alcohols on cellulose tribenzoate (1996)
    Springer
    Chromatographia 42 (1996), S. 462-464 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Alcohols ; Cellulose tribenzoate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Cellulose tribenzoate (CTB) has some desirable operational properties and special interactions with alcohols. When chromatographic separation is carried out at 150°C, the C1–C4 alcohols have enhanced retention and other alcohols are eluted rapidly. Some probe molecules were used to characterize the chromatographic behavior of CTB by calculating the adsorption enthalpy (−ΔHa) between the sample and stationary phase. Separation of aliphatic alcohols was successfully performed on a packed column with a support (GDX) coated with CTB and temperature programming improved the separation of these alcohols.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272139
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  • 59
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    Electronic Resource
    Gas chromatographic determination of rate constants in bimolecular gaseous reactions (1996)
    Springer
    Chromatographia 42 (1996), S. 441-450 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Reversed-flow technique ; Rate constants ; Bimolecular gaseous reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Rate constants for bimolecular reactions in the gas phase, under diffusion controlled conditions, can easily be determined by the reversed-flow gas chromatography (RF-GC) technique. The analysis of the diffusion band by means of a simple PC programme gives directly an apparent, second-order rate constant for gaseous reactions. By varying the amounts of the reactants, one can calculate the true order of the reaction and the true non-first-order rate constant of gaseous reactions. The calibration problem of the analytical techniques in non-first-order reaction kinetics is absent as are other disadvantages connected with carrier gas flow, peak shape and their instrumental spreading. The method can be used for atmospheric reactions and was applied in the gaseous reaction systems: SO2+NO2, SO2+Br2, C6H6+NO2, C6H5CH3+NO2 and C3H6+NO2 with various concentrations of reactants in nitrogen. The effect of the NO2 concentration on the apparent second-order rate constant of C2H4+NO2 at 333.2 K was also studied. Finally, the effect of sun light pre-irradiation of C2H2+NO2 in nitrogen was investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272137
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  • 60
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    Electronic Resource
    A simple detection system for gas chromatography based on molecular absorption spectrometry in the gas phase (1996)
    Springer
    Chromatographia 42 (1996), S. 435-440 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Molecular absorption spectrometry ; Gas phase detection ; Benzene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and inexpensive detection system for gas chromatography, based on gas-phase, molecular absorption measurements, is presented in which the chromatographic column is directly joined to the spectrophotometer flow cell, without heated transfer lines. A mixture of eight benzene compounds (including methyl, halogen and nitrogen derivatives) were separated and analyzed. Parameters affecting separation (temperature program and carrier gas flow) and measurement quality (wavelength and integration time) were studied and a measurement program designed to modify the wavelength during chromatography. The analytical characteristics of each compound were calculated, obtaining detection limits ranging from 0.5 to 9 μg mL−1. Finally, the method was applied to several synthetic mixtures, with good results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272136
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  • 61
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    Electronic Resource
    Gas chromatographic separation of low-boiling pyridine bases (1996)
    Springer
    Chromatographia 42 (1996), S. 465-468 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Packed column separations ; Pyridine and alkylpyridines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The gas chromatography of the β-picolines in a lowboiling tar base fraction, is described. The methods developed employ packed columns with binary phases containing N,N,N′,N′-tetrakis(2-hydroxypropyl) ethylenediamine plus metal transition stearate, or with a ternary phase containing this mixture and o-hydroxyethylresorcinol
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272140
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  • 62
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    Electronic Resource
    Supercritical fluid extraction of chlorothalonil residues from apples (1996)
    Springer
    Chromatographia 42 (1996), S. 547-550 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Supercritical Fluid Extraction ; Pesticides Residues ; Chlorothalonil ; Appels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method for the extraction of Chlorothalonil residues from apples using supercritical CO2 as the extracting fluid is described. The supercritical fluid extraction results were compared with those obtained by solid-liquid extraction. The results showed that SFE is faster and more selective with better recovery and higher selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290289
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  • 63
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    Electronic Resource
    Low-level determination of EDTA and DTPA in natural waters by gas chromatography (1996)
    Springer
    Chromatographia 42 (1996), S. 578-582 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; EDTA determination ; DTPA determination ; Water analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new analytical method and the method validation for the determination of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) in lake and sea water is presented. An aqueous sample, after evaporation to dryness, was treated with an esterification reagent. The resulting ethyl ester derivates were determined by capillary gas chromatography using a nitrogen phosphorus specific detector (GC-NPD). The response was linear up to 5 mg L−1. The recoveries from lake and sea waters were 59–105 % for EDTA and 86–112 % for DTPA. The run-to-run repeatabilities (R.S.D.) were 2–8 % for EDTA and 4–11 % for DTPA depending on concentration and the reproducibilities (R.S.D.) were 6–13 % and 3–11 %, respectively. The limits of detection for EDTA and DTPA were 3 and 12 μg L−1 in distilled water, respectively. The method is simple to use and reliable as shown by the analysis of samples of lake water that is influenced by pulp and paper industry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290295
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  • 64
    Electronic Resource
    Electronic Resource
    Comparison of GC-ECD, GC-MS and GC-AED for the determination of polychlorinated biphenyls in highly contaminated marine sediments (1996)
    Springer
    Chromatographia 43 (1996), S. 44-52 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron capture detection ; Mass spectrometric detection ; Atomic emission detection ; PCBs in marine sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Electron capture detection (ECD), low- and highresolution mass spectrometry (LR- and HRMS), and atomic emission detection (AED) were compared for the gas chromatographic (GC) detection of polychlorinated biphenyls (PCBs) present in highly contaminated marine sediments. With ECD, LRMS, and even HRMS, detection was seriously disturbed by the complex matrix of the sediments, whereas AED in the chlorine-selective mode provided excellent PCB profiles without interferences. In addition, GC-AED provided congener independent responses, which enabled accurate quantitation of all PCBs based on a single calibration curve. However, because GC-AED was less sensitive than the other techniques studied, preparation of relatively large amounts of sample (10–20 g dry sediment) was required for most analyses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272820
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  • 65
    Electronic Resource
    Electronic Resource
    Spatial average velocity of carrier gas is proportional to column pressure drop (1996)
    Springer
    Chromatographia 43 (1996), S. 73-75 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Spatial average gas velocity ; Temporal average gas velocity ; Column pressure drop
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary While the commonly known temporal average velocity of a carrier gas is approximately proportional to the pressure drop along a column, the spatial average velocity is exactly proportional to that pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272824
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  • 66
    Electronic Resource
    Electronic Resource
    Automatic preconcentration of chlorophenols and gas chromatographic determination with electron capture detection (1996)
    Springer
    Chromatographia 43 (1996), S. 633-639 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron capture detection ; Solid phase extraction ; Chlorophenols ; Water analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A solid-phase extraction system coupled to a gas chromatograph fitted with an electron capture detector was developed for the determination of chlorophenols in waters. The continuous system consists of an XAD-2 adsorbent column where chlorinated phenols are preconcentrated and subsequently eluted with ethyl acetate. The sensitivity of the method is proportional to the number of chlorine substituents in the phenol; thus, the detection limit for monochlorophenols is ca. 10 μg L−1 and that for pentachlorophenol about 2 ng L−1. The method was used to determine chlorophenols in treated waters, with good precision; however, no mono or dichlorophenols were detected at the levels afforded by the proposed method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292980
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  • 67
    Electronic Resource
    Electronic Resource
    Correlation equations describing retention index data forn-alkylcyclopentenes,n-alkylcyclohexenes andn-alkyl esters on OV-101, OV-225 and PEG 20M (1996)
    Springer
    Chromatographia 43 (1996), S. 557-558 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention indices ; Correlation equations ; n-Alkylcyclopentenes andn-alkylcyclohexenes ; n-Alkyl esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Correlation equations have been derived which relate the Kováts retention indices ofn-alkylcyclopentenes,n-alkylcyclohexenes andn-alkyl esters of aliphatic acids on the stationary phases OV-101, OV-225 and PEG 20M to column temperature and carbon number in the alkyl chain. The universal equation: $$\begin{gathered} RI = A + B \cdot m + C \cdot \log (m)/m + \hfill \\ D/[(m - 2)^2 + 0.1] + Et \hfill \\ \end{gathered} $$ whereA, B, C, D andE are correlation coefficients,m is the number of carbon atoms in the side chain (forn-alkylcycloalkenes) or in the alcohol chain (for alkyl esters) andt is the column temperature, describes the retention indicesRI of these homologous series with high accuracy (SD〈1 index unit), beginning with the first members of the series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293010
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  • 68
    Electronic Resource
    Electronic Resource
    Gas chromatographic (GC) method for the determination of SCH 44643, an orally active antagonist of platelet activating factor in rat plasma (1996)
    Springer
    Chromatographia 43 (1996), S. 533-536 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase extraction ; Nitrogen phosphorus detector ; SCH 44643 in rat plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic (GC) assay for the determination of SCH 44643, an orally active antagonist of responses to both histamine and PAF, was developed and validated for rat plasma. The method involved organic solvent extraction followed by solid phase extraction on aminopropyl column. The separation was on a capillary column (DB-17) with quantitation by a nitrogen-phosphorus detection. The method was sensitive with a limit of quantitation of 5 ng mL−1. There was a good linear relationship between the peak height ratio (SCH 44643/internal standard) and SCH 44643 concentration in the range 5 to 200 ng mL−1. The method was precise with a coefficient of variation ranging from 1.8 to 3.0% and accurate with a bias ranging from 0 to 5.8%. Moreover, SCH 44643 was stable in rat plasma after being subjected to three freeze-thaw cycles. The assay was shown to be sensitive, specific, accurate and precise, and suitable for use in pharmacokinetic or toxicokinetic studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293006
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  • 69
    Electronic Resource
    Electronic Resource
    Gas chromatographic properties of two thermotropic Poly(L-glutamates) with long alkyl side chains (1996)
    Springer
    Chromatographia 43 (1996), S. 387-392 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Poly(L-glutamate) ; Cholesteric liquid crystal ; Properties as stationary phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Comparative gas chromatographic properties of two thermotropic Poly(L-glutamates) with long alkyl side chains (10 and 16 carbons called Poly 10 and Poly 16 respectively) are studied. Their thermal properties were established with differential scanning calorimetry (DSC) and gas chromatography. They present a cholesteric liquid crystal in a large temperature range. The chromatographic separation abilities of the two polymers in the liquid crystal state were studied using capillary glass columns. Interesting analytical performances were obtained in different fields: isomeric separation of alkanes, aromatics, polyaromatics, volatile aroma compounds and cis and trans isomers. Some differences were noticed in their behaviours; 2 and 3-methyloctane and xylene isomers are separated only on Poly 10 while limonene and eucalyptol are separated only on Poly 16.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271016
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  • 70
    Electronic Resource
    Electronic Resource
    Simultaneous determination of aliphatic hydrocarbons, PCBs and PCTs in pork liver by gas chromatography (1996)
    Springer
    Chromatographia 43 (1996), S. 398-400 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Aliphatic hydrocarbons ; Chlorinated aromatics ; Pork liver extracts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A multicomponent extraction/concentration procedure has been developed for the enrichment of PCBs, PCTs and aliphatic hydrocarbons (pristane, C18, C19, C20, C22, C24, C28, C32 and C36) in pork liver. These components of the enriched extract were then simultaneously determined by gas chromatography. Mean recoveries ranged from 81.5% for pristane to 93% for PCBs;CV% (0.9–6.7) indicated the method to be both precise and reproducible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271018
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  • 71
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    Electronic Resource
    A study of the surface modification of alumina for GC (1996)
    Springer
    Chromatographia 42 (1996), S. 77-82 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Modified alumina ; Coal mine air ; Alkenes, alkanes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatographic method for the separation of alkanes and alkenes present in coal mine air has been developed using modified alumina columns. The separation was carried out using a GC equipped with a gas sampling valve, a FID and a surface modified alumina packed column with helium as carrier gas. An investigation was carried out into the effects of surface modifiers on alumina. The study examined the change in retention properties on alumina modified by alkali metal salts and the specific effects of the halide anions and metal cations. The paper describes the preparation of the alumina columns and the effects on selectivity of post heating the stationary phase. The study demonstrated that alumina modified with 2% sodium chloride and post heated to 150°C was the most appropriate stationary phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271059
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  • 72
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    Electronic Resource
    Detection of organophosphate pesticides in human body fluids by headspace solid-phase microextraction (SPME) and capillary gas chromatography with nitrogen-phosphorus detection (1996)
    Springer
    Chromatographia 42 (1996), S. 135-140 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace sampling ; Solid-phase microextraction (SPME) ; Nitrogen-phosphorus detection (NPD) ; Organophosphate pesticides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Organosphosphate pesticides have been found extractable by headspace solid-phase microextraction (SPME), and the best conditions of their extraction from human whole blood and urine samples have been investigated. The body fluid samples containing nine pesticides (IBP, methyl parathion, fenitrothion, malathion, fenthion, isoxathion, ethion, EPN and phosalone) were heated at 100°C in a septum-capped vial in the presence of various combinations of acid and salts, and SPME fiber was exposed to the headspace of the vial to allow adsorption of the pesticides before capillary gas chromatography (GC) with nitrogen-phosphorus detection. The heating with distilled water/HCl/(NH4)2SO4/NaCl and with distilled water/HCl gave the best results for urine and whole blood, respectively. Recoveries of the nine pesticides were 0.8–10.6% except for phosalone (0.03%) for whole blood, and 3.8–40.2% for urine. The calibration curves for the pesticides showed linearity in the range of 50–400 ng/0.5 mL for whole blood except for malathion (100–400 ng/0.5 mL whole blood) and 7.5–120 ng/0.5 mL for urine except for phosalone (15–120 ng/0.5 mL urine) with detection limits of 2.2–40 ng/0.5 mL for whole blood and 0.8–12 ng/0.5 mL for urine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269642
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  • 73
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    Electronic Resource
    Complete separation of ephedrines by graphite-layer open-tubular (GLOT) column (1996)
    Springer
    Chromatographia 42 (1996), S. 309-312 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Graphite coated capillary columns ; Ephedrines separation ; Drug analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of graphite-layer capillary column is described together with their application to the analysis of aliphatic and aromatic amines. Attention is mainly focused on the separation of ephedrines which, being sympathomimetic amines, are often present in pharmaceutical preparations, but are also illegally used by athletes as stimulants. Complete separation of these compounds, using direct GC-NPD analysis of human urine extract, without derivatisation, has been obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290315
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  • 74
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    Electronic Resource
    Gas and liquid chromatography and enzyme linked immuno sorbent assay in pesticide monitoring of surface water from the western mediterranean (Comunidad Valenciana, Spain) (1996)
    Springer
    Chromatographia 42 (1996), S. 151-158 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Pesticide residues ; Surface water analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A monitoring programme based on gas chromatography (NPD, ECD) using MSD for confirmatory purposes and coupled-column liquid chromatography was applied to the analysis of pesticide residues in surface water from a predominantly agricultural area of Spain (Comunidad Valenciana). Samples analysed by means of enzyme-linked immunosorbent assay gave similar results to those obtained by GC (MSD) for the determination of total triazines. The test employed had the advantages of a simple test procedure, short analysis time and high confirmatory value. Nevertheless, the multiresidue character, accuracy and unequivocal identification of individual pesticide residues of GC (MSD) make this technique the most appropriate for environmental monitoring programmes. In this monitoring programme about 200 samples were analysed between 1993–1994. 27 different pesticides were detected in 91 of these samples. The pesticides more frequently detected were dimethoate, methidathion, endosulfan A and B, endosulfan sulphate and pirimicarb. The highest concentrations found were 39.9 μg L−1 of dimethoate, 10.6 of pirimicarb and 10.6 of methidathion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269645
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  • 75
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    Electronic Resource
    Simultaneous extraction of norflurazon and oxadixyl residues from food crops with supercritical carbon dioxide (1996)
    Springer
    Chromatographia 42 (1996), S. 147-150 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Supercritical fluid extraction ; Pesticide residues ; Norflurazon residues ; Oxadixyl residues ; Food crops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Norflurazon and Oxadixyl residues have been analysed by HRGC-ECD after extraction from field-treated sugar cane and grapes using classical solid-liquid extraction or supercritical fluid extraction. The extraction techniques were compared; the results indicate the advantages of SFE as an alternative method for analysis of pesticides in these samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269644
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  • 76
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    Electronic Resource
    Fast and effective sample preparation for determination of organochlorine compounds in fatty tissue of marine mammals using microwave extraction (1996)
    Springer
    Chromatographia 42 (1996), S. 300-304 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Microwave extraction ; Sample clean-up ; Organochlorine compounds ; Blubber of marine mammals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and effective method is described for the extraction of organochlorine compounds (PCB 153, PCB 138, PCB 180, p,p′-DDE, α-HCH, γ-HCH, ε-HCH and HCB) from seal blubber and pork fat withn-hexane using a microwave technique. Heating of the non-polarn-hexane was achieved using a microwave transformer. The lipid content of the samples obtained by this extraction was identical to that by Soxhlet extraction. After separation of sample matrix and organochlorines on a silica gel column the organochlorine compounds were determined by GC-ECD. The efficiency of the method was tested with 500 mg spiked fat, extracted using various numbers of extraction cycles. Recoveries of organochlorine compounds in grey seal blubber and spiked pork fat generally exceeded 90 %.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290313
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  • 77
    Electronic Resource
    Electronic Resource
    Determination of chloroethenes in environmental biological samples using gas chromatography coupled with solid phase micro extraction (1996)
    Springer
    Chromatographia 42 (1996), S. 313-317 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase micro extraction ; Chloroethenes ; Reductive dechlorination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An analytical method has been developed to determine the chloroethene series, tetrachloroethene (PCE), trichloroethene (TCE),cisdichloroethene (cis-DCE) andtransdichloroethene (trans-DCE) in environmental biotreatment studies using gas chromatography coupled with a solid phase micro extraction (SPME) technique. The volatile chlorinated compounds in aqueous solution can be analyzed directly without solvent extraction, purge and trap, or thermal heating. The calibration curves have demonstrated good linear relationships within 50.0 to 3000.0 μg L−1 concentration range. Detection limits are 18.0, 5.0, 25.0, and 42.0 μg L−1, for PCE, TCE,cis-DCE andtrans-DCE, respectively. Factors which affect the SPME process, such as sample adsorption time, thermal desorption time, and concentration of salt in the matrix, have also been evaluated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290316
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  • 78
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    Electronic Resource
    Extraction of local anaesthetics from human blood by direct immersion-solid phase micro extraction (SPME) (1996)
    Springer
    Chromatographia 43 (1996), S. 59-62 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Local anaesthetics ; Solid phase micro extraction (SPME) ; Direct immersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Local anaesthetics have been shown to be extractable from human whole blood samples by direct immersion (DI)-solid phase micro extraction (SPME). After deproteinization with perchloric acid, the pH of the clear supernatants of human whole blood samples containing the drugs were adjusted to about 7 with 10 M NaOH in the presence of NaCl; a polydimethylsiloxanecoated SPME fiber was then immersed directly into the sample solution to allow adsorption of the drugs before capillary gas chromatography (GC) with flame ionization detection. The DI-SPME for 1-mL whole blood gave peaks for all the drugs; only a small amount of background noise appeared and this gave no problems in the detection of the drugs. Recoveries of the ten drugs from human whole blood was 0.74–19.7 %. The calibration curves for seven drugs showed linearity in the range of 0.25–12 μg mL−1 whole blood, with detection limits of 54–158 ng mL−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272822
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  • 79
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    Electronic Resource
    Investigation into the separation of achiral and chiral molecules on fused-silica capillary columns coated with three peralkylated cyclodextrins (1996)
    Springer
    Chromatographia 43 (1996), S. 628-632 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phase ; β-Cyclodextrin ; Separation mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three peralkylated β-cyclodextrins (CD), perethylated β-CD, perbutylated β-CD and peroctylated β-CD have been coated on to untreated fused-silica capillary tubing and used to separate some achiral and chiral compounds. The separation mechanism is discussed in the paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292979
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  • 80
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    Electronic Resource
    GC-ECD evaluation of dicofol toxicity to tropicalAstyanax bimaculatus schubarti (1996)
    Springer
    Chromatographia 43 (1996), S. 663-667 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Dicofol ; Fish ; Lethal concentration ; Bioconcentration factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Evaluation of the toxicity of Dicofol was carried out onAstyanax bimaculatus schubarti, a characteristic fish species living in tropical rivers and lakes. Experiments were under laboratory controlled conditions with atmospheric air flow and dilution water at 25°C in the static mode. Fish samples were collected and submitted to appropriate analytical procedure: Soxhlet extraction, clean-up by Florisil adsorbent and finally quantification by GC-ECD. The results showed good recoveries (〉 89%) for the developed method both in water and fish samples. The lethal concentration, LC50, and the bioconcentration factor, BCF, were 18.13 mg L−1 and 241.70, respectively forAstyanax bimaculatus schubarti demonstrating the lipophilic nature of the studied compound.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292985
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  • 81
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    Electronic Resource
    Electronic pressure control of gas chromatography-mass spectrometry for the confirmation of pesticide residues in cereals and related products (1996)
    Springer
    Chromatographia 43 (1996), S. 177-180 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electronic pressure control ; Mass selective detector ; Pesticide residues ; Cereals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An analytical method for the confirmation of 30 pesticide residues in cereals and related products has been developed. Splitless injection with electronic pressure control using constant carrier gas flow gives higher sensitivity and better resolution than electronic pressure control and isobaric analysis. The use of electronic pressure control assures consistent retention times enabling selected ions to be collected in short time windows. Mass spectrometric detection in the selected ion monitoring mode using three ions for each pesticide ensured good sensitivity and accurate pesticide confirmation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292947
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  • 82
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    Electronic Resource
    Gas chromatographic separation of expoxystyrenes on carbowax 20 M capillary column (1996)
    Springer
    Chromatographia 43 (1996), S. 208-210 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Epoxystyrenes ; Retention index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of some epoxystyrenes on fused silica capillary columns coated with poly(ethylene glycol) was investigated, Retention indices were determined at two temperatures to interpret chromatographic behaviour, The standard deviation was 0.3 index units.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292953
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  • 83
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    Electronic Resource
    Microwave assisted solvent extraction (MASE) for the efficient determination of triazines in soil samples with aged residues (1996)
    Springer
    Chromatographia 43 (1996), S. 527-532 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Microwave-assistend solvent extraction (MASE) ; Pesticide residue analysis ; Triazine herbicides ; Soil samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of microwave-assisted solvent extraction (MASE) as an alternative for conventional solvent extraction procedures for the determination of some triazine herbicides in soil samples has been investigated. In this study MASE method development was focused on the selection of a suitable extraction solvent prior to the instrumental analysis of uncleaned extracts with gas chromatography and nitrogen-specific detection. A mixture of dichloromethane-methanol (90∶10, v/v) yielded recoveries ranging from 89 to 103 (spiked level 200 μg/kg) with RSDs ranging from 2.1 to 5.3%. This solvent mixture is also very convenient for further procedure. The selected MASE procedure was tested by analyzing freshly spiked soil samples and samples with aged residues of atrazine, desethylatrazine, desisopropylatrazine and simazine. The results were compared with those obtained by a conventional liquid extraction method. The comparative study indicated that MASE yields recoveries at least as good as those obtained by the conventional method. Moreover, the MASE procedure provides low solvent consumption in combination with a high sample throughput.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293005
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  • 84
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    Electronic Resource
    Determination of fosfomycin in human urine by capillary gas chromatography: Application to clinical pharmacokinetic studies (1996)
    Springer
    Chromatographia 43 (1996), S. 293-295 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fosfomycin in urine ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A capillary gas chromatographic method for the determination of fosfomycin in human urine is described. After dilution of the sample and derivatization, analysis was on a HP-1 capillary column and a flame ionization detector was used to determine the bistrimethylsilyl derivative of fosfomycin. Response was linear in the range 50–5000 μg mL−1. The detection limit was about 10 μg mL−1. The within and between day coefficients of variation did not exceed 6%. The method was applied to the determination of fosfomycin in urine samples collected during clinical pharmacokinetic studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02270997
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  • 85
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    Electronic Resource
    Gas chromatography with flame ionization and flameless sulfur chemiluminescence detectors in series for dual channel detection of sulfur compounds (1996)
    Springer
    Chromatographia 43 (1996), S. 522-526 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sulfur chemiluminescence detector ; Flame ionisation ; Dual-channel detection ; Optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The dual-channel detection of samples with detectors coupled in series is possible only when the first detector is a non-destructive one. However, the configuration where a destructive detector, such as the flame ionization detector (FID), is followed by the flameless, sulfur chemiluminescence detector (flameless SCD) can be used to detect simultaneously carbon and sulfur. In this work, the FID and flameless SCD are coupled in series for dual-channel detection of sulfur compounds in three gasoline samples. Optimum conditions for flameless SCD were evaluated by altering the flow rates of hydrogen and air and the oxygen pressure to the ozone generator. Samples are identified by retention indices where the homologous n-alkylthiols are used as standards. The increment in retention index per carbon number of the n-alkylthiols is 105.54 in the Quadrex 007 series, 0.32 mm i.d., 4 μm film, column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293004
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  • 86
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    Electronic Resource
    Consequence of diluting modified β-cyclodextrins in a side-chain crown ether polysiloxane and in a side-chain liquid-crystalline polysiloxane-containing crown ether as stationary phases in capillary gas chromatography (1996)
    Springer
    Chromatographia 43 (1996), S. 546-550 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Stationary phase ; Polysiloxane matrices ; β-Cyclodextrin ; Crown ether ; Liquid crystal ; Coordination effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper investigates the possibility of using a sidechain crown ether polysiloxane (PDB-14-C4) and a side-chain liquid-crystalline polysiloxane-containing crown ether (PSC-3) as matrices for peralkylated β-CD employed as stationary phases. Three columns, coated with PSC-3 + permethylated β-CD, PDB-14-C4 + permethylated β-CD and PDB-14-C4 + perethylated β-CD were characterized by gas chromatography. The column efficiencies, phase transitions, and selectivities were measured and compared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02293008
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  • 87
    Electronic Resource
    Electronic Resource
    Separation of a gasoline on an open tubular column with 1.3 million effective plates (1996)
    Springer
    Chromatographia 42 (1996), S. 63-71 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; High efficiency open tubular columns ; Columns connected in series ; Gasoline analysis ; Detailed hydrocarbon analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary More than 1.3 million effective plates were produced by a column 450 meters long, 200 μm inner diameter. The column was built up by connecting nine 50 meter columns in series. The sum of the efficiencies of the individual pieces equalled the efficiency of the combined column. Up to 970 components were differentiated in a gasoline standard.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271057
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  • 88
    Electronic Resource
    Electronic Resource
    A computerized analysis of the sulfur content in diesel fuel by capillary gas chromatography with flame photometric detector (1996)
    Springer
    Chromatographia 42 (1996), S. 631-638 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; flame photometric detector ; Sulfur in diesel fuel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method is proposed for the computerized determination of sulfur in diesel fuel by capillary gas chromatography with a flame photometric detector (FPD). The diesel fuel is injected in the gas chromatograph after dilution with n-hexane. After recording the chromatogram, the sulfur content in the diesel fuel (mg L−1 or w/w) is given directly by an integrator provided with a Basic card or by a personal computer in which the algorithm of the calibration curve has been entered. Use of a calibration curve does not require the identification of the numerous sulfur compounds present in diesel fuel. The calibration curve was corrected for the quenching effect that the hydrocarbon components of the diesel fuel produce on the detector response. The method was tested using diesel fuel with a known sulfur concentration and was found to be very accurate; it is reproducible, fast and may be automated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267694
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  • 89
    Electronic Resource
    Electronic Resource
    Classification of the botanical origin of cinnamon by solid-phase microextraction and gas chromatography (1996)
    Springer
    Chromatographia 42 (1996), S. 639-646 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Semivolatile flavor compounds ; Cinnamon ; Solid-phase microextraction ; Chemometric classification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The conditions which affect the reproducibility of characteristic chromatographic profiles of semivolatile compounds from true cinnamon and cassia by headspace solid-phase microextraction are determined. Optimum conditions for sample amount, vial size, temperature, sampling time, and fiber type for steady state sampling conditions are identified. Vial size was an unexpected critical parameter possibly related to the build up of internal ternal pressure during sample heating followed by expulsion of a portion of the vapor phase through the septum as it was punctured by the syringe. Gas chromatography with ion trap mass spectrometry was used to identify the major volatile compounds in cassia and true cinnamon. Reasonable semi-quantitative agreement (r 2〉0.87 and generally greater than 0.93) was observed for the major semivolatile compounds isolated by headspace solid-phase microextraction and solvent-assisted supercritical fluid extraction. The extracts isolated by solid-phase microextraction contained relatively high concentrations of terpene-type compounds in low abundance in the solvent-assisted supercritical fluid extracts, but these compounds were of little value in distinguishing the botanical origin of authentic cinnamon and cassia samples. The latter were easily distinguished by the presence of eugenol and benzyl benzoate in true cinnamon, that was absent in cassia, and the presence of coumarin and δ-cadinene, in cassia, that was either absent or in low concentration in true cinnamon. Headspace solid-phase microextraction provides a rapid and simple method for establishing the botanical origin of the principal cinnamons of commerce.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267695
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  • 90
    Electronic Resource
    Electronic Resource
    CGC/AED and CGC/ECD/NPD comparison for the determination of acaricides in honey after hexane/acetone extraction (1996)
    Springer
    Chromatographia 42 (1996), S. 130-134 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Atomic emission, electron capture ; and nitrogen phosphorus detection ; Honey ; Acaricides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The performance of a gas chromatographic system coupled to an atomic emission detector (GC/AED) is tested by comparison with a two-dimensional gas chromatographic system equipped with capillary columns of different polarity and simultaneous electron capture and nitrogen-phosphorus detection (ECD/NPD), for the determination of the acaricides chlordimeform, bromopropylate, amitraz and coumaphos on spiked honey samples. The acaricides were extracted with ann-hexane/acetone mixture (80∶20, v/v) with a further clean-up step on an octadecylsilane cartridge. The 193 nm carbon emission line is the best choice in terms of sensitivity whereas the ECD/NPD system gives better selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269641
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  • 91
    Electronic Resource
    Electronic Resource
    Synthesis of chemically bonded squalene(ane) phases for microcolumn gas chromatographic separation of low-molecular-weight hydrocarbons in extraterrestrial atmospheres (1996)
    Springer
    Chromatographia 42 (1996), S. 141-146 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Low-molecular-weight hydrocarbons ; Extraterrestrial atmospheres ; Chemically bonded squalene(ane) phase ; 13C and29Si CP-MAS NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chemically bonded squalene(ene) phases have been synthesized via a hydride modified silanization process using dimethylchlorosilane, triethoxysilane and trichlorosilane. The surface structure of the bonded phases were characterized with DRIFT and solid state NMR studies. The results of the latter indicate successful bonding of a non-terminal olefin to the silica surface and that bonding of individual squalene molecules appeared not to occur at the same site(s) presumably due to steric hindrance. Among the phases examined, the trichlorosilane-based material exhibits better chromatographic properties probably due to greater surface coverage and hence effective non-polar interaction between the solutes and the bonded ligands. Under isothermal conditions, the present packings produced fast and efficient separation of C1–C4 saturated hydrocarbons on shorter columns than similar columns containing alkyl- or bidentate alkyl-modified silica packings at low column head pressure and are thermally stable at temperatures up to 250°C or higher.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269643
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  • 92
    Electronic Resource
    Electronic Resource
    Simultaneous gas chromatographic determination of methanol and free glycerol in biodiesel (1996)
    Springer
    Chromatographia 42 (1996), S. 431-434 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fatty acid methyl esters ; Biodiesel ; Methanol ; Glycerol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The methanol and free glycerol content of vegetable oil methyl esters used as diesel fuel (biodiesel) is very important in describing the quality of this fuel and is therefore limited by specifications. A previously described GLC method for the determination of free glycerol in biodiesel has been further developed and also allows the simultaneous determination of methanol. Sample preparation includes dissolving in dimethylformamide, silylation with bis-trimethylsilyltrifluoracetamide (BSTFA) and separation on a methylsilicone fluid, coated-capillary column using either FID or MS-detection. Ethanol and 1,4-butanediol were used as internal standards. Both detection systems show sufficient sensitivity for concentrations relevant to biodiesel samples. The recovery was tested using a RME-sample containing known amounts of methanol and glycerol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272135
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  • 93
    Electronic Resource
    Electronic Resource
    Gas chromatographic and differential scanning calorimetric studies of new bonded silicas in connection with transition phenomena (1996)
    Springer
    Chromatographia 42 (1996), S. 451-461 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Bonded silicas ; Phase transitions ; Differential scanning calorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to give a molecular interpretation to the phase transition observed with densely bonded octadecyl-silicas in reversed phase liquid chromatography (RPLC) as well as in gas chromatography (GC), nine new bonded silicas were prepared including grafts with polar groups at the extremities of long spacers (18 carbon atoms). The interpretation is simplified by using large-pore macroporous substrates and inverse GC in conjunction with differential scanning calorimetry (DSC) as the test method. A phase transition is observed in almost all cases, but the temperature range is lower and more extended in comparison to the dimethyloctadecyl reference silica. An interpretation of the phase transition is given, based on the folding of the chains and the resulting “autodensification” of the layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272138
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  • 94
    Electronic Resource
    Electronic Resource
    Capillary gas chromatography of double-base propellants (1996)
    Springer
    Chromatographia 42 (1996), S. 593-594 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Double-base propellants ; Nitroglycerin ; Centralite I ; Dibutyl phthalate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation and quantitative determination of propellant constituents on short, wide-bore fused-silica capillary columns, coated with crosslinked methylsilicone phase was investigated. The analytical results were quite satisfactory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290298
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  • 95
    Electronic Resource
    Electronic Resource
    Determination of partition coefficients and residual solvent for polymer drying applications (1996)
    Springer
    Chromatographia 43 (1996), S. 31-38 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Partition coefficients ; Henry's constants ; High density polyethylene ; Polymer drying
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas-solid partition coefficients (K) for n-hexane in high density polyethylene (HDPE) have been measured at conditions applicable to large-scale drying utilizing a novel headspace method. The method features considerable versability and simplicity due to the control of experimental conditions designed to favor full extraction of the analyte into the headspace. By combining this full extraction technique with a traditional static headspace experimental scheme, a method which measuresK and residual concentration is achieved. The results show that partition coefficients differ significantly between HDPE in its virgin powder and pellet forms, as well as among various HDPE grades. The differences are shown to be attributable to differences in % crystallinity of the specific polymer. Data collected over a wide range of hexane concentrations reveals saturation levels (solubilities) which correspond to crossover from evaporative to diffusion-controlled drying.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272818
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  • 96
    Electronic Resource
    Electronic Resource
    Determination of formaldehyde in foods, biological media and technological materials by headspace gas chromatography (1996)
    Springer
    Chromatographia 43 (1996), S. 625-627 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace sampling ; Formaldehyde ; Plastics ; Foods ; Biological samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A modified headspace gas chromatographic method, based on polycondensation with formaldehyde, has been developed for derivatization with formaldehyde in foods, biological media and other products. The method provides the possibility of obtaining results within three minutes, which is of significant importance for the control of food and cosmetics production and the quality of polymer products based on formaldehyde, as well as for biological monitoring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292978
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  • 97
    Electronic Resource
    Electronic Resource
    The physical meaning of the corrected retention volume (1996)
    Springer
    Chromatographia 43 (1996), S. 159-162 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Gas pressures ; Gas compressibility ; Retention volumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The true meanings of the so-called corrected retention volume and the specific retention volume are explained in the light of the recent paper by Davankov.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292945
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  • 98
    Electronic Resource
    Electronic Resource
    Use of incremental models to estimate the retention indexes of aromatic compounds (1996)
    Springer
    Chromatographia 43 (1996), S. 163-176 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Retention index estimation ; Aromatic compounds ; Incremental models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Pure topologically based incremental models have been developed in order to estimate the retention indexes of aromatic compounds substituted with groups containing the hetero atoms nitrogen, oxygen and halogens. The bond-types of the compounds are counted and used as molecular descriptors. The observed estimation errors are about 1 % for compounds containing no hetero atoms and for those containing halogenated substituents; the errors are approximately 2 % for aromatic compounds with nitrogen- and oxygen-containing substituents. The method is validated by prediction of the retention indexes for an additional group of aromatic compounds (the validation data set).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292946
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  • 99
    Electronic Resource
    Electronic Resource
    Investigation of gas chromatographic interaction mechanism on permethylated cyclodextrins by molecular modelling (1996)
    Springer
    Chromatographia 43 (1996), S. 187-194 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Molecular modelling ; Molecular mechanics calculations ; Permethylated α-, β- and γ-cyclodextrins ; Interaction mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The capillary gas chromatographic retention behavior of α-pinene and tricyclene has been investigated on stationary phases of different polarities. On all but one of the columns employed, tricyclene eluted before α-pinene; only permethylated β-cyclodextrins dissolved in moderately polar polisiloxanes gave a reversed elution order. The intermolecular interactions which caused the unexpected retention behavior were investigated in detail, applying methods of computer simulation. To achieve this, we have developed a calculation algorithm on the basis of molecular mechanical optimizations and programmed it in a macro. This makes it possible to systematically investigate a given configuration space in which all the possible interactions can take place. It was shown that permethylated β-cyclodextrin as host molecule for both guest molecules offers an optimum cavity size. As a result the number of energetically favorable contacts between host and guest molecules as well as the strength of the interactions in this stationary phase were larger. As a consequence the elution order, normally only influenced by the vapor pressure of the compounds at a given temperature, was changed. Nonspecific interactions played an especially important role for these kinds of substances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292949
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  • 100
    Electronic Resource
    Electronic Resource
    Evaluation of 3,5-stigmastadiene content of edible oils: Comparison between the traditional capillary gas chromatographic method and the on-line high performance liquid chromatography-capillary gas chromatographic analysis (1996)
    Springer
    Chromatographia 43 (1996), S. 195-199 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography-gas chromatography ; Gas chromatography ; 3,5-Stigmastadiene ; Cold pressed olive oil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The quantitation of 3,5-stigmastadiene and other steroidal hydrocarbons, commonly known as steradienes, is a valid tool for the recognition of refining (in particular bleaching) of edible oils; the evidence of this process is nowadays of a great interest due to growing market for “virgin”, cold-pressed, “natural” oils. Due to the long time required (about 4 hours) and the amount of solvents employed (about 650 mL) to perform the official analysis, other methods have been recently proposed, the most important of which involves high performance liquid chromatography coupled with capillary gas chromatography (HPLC-GC). In this study the results of ten oil samples, analysed by both the official method and HPLC-GC, are reported and the two methods compared and discussed, for routine use, in terms of sample preparation, time of analysis and setting up, difficulty and reproducibility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02292950
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