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  • Artikel: DFG Deutsche Nationallizenzen  (142)
  • 2015-2019
  • 1990-1994  (44)
  • 1980-1984  (98)
  • 1970-1974
  • 1820-1829
  • 1994  (44)
  • 1982  (98)
  • 1829
  • Gas chromatography
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  • Artikel: DFG Deutsche Nationallizenzen  (142)
Materialart
Erscheinungszeitraum
  • 2015-2019
  • 1990-1994  (44)
  • 1980-1984  (98)
  • 1970-1974
  • 1820-1829
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Amino acids 6 (1994), S. 205-211 
    ISSN: 1438-2199
    Schlagwort(e): Amino acids ; Amino acid enantiomers ; Chiral analysis ; Chirasil-L-Val ; Gas chromatography ; Mass spectrometry ; Selected ion monitoring ; D-Serine ; D-Alanine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The relative amounts of free D-amino acids (D-AA) in the urine of seven healthy volunteers (age 27 to 49 years) were determined using chiral phase (Chirasil-L-Val) capillary gas chromatography in conjunction with selected ion monitoring mass spectrometry. The absolute amounts of free D-AA were determined by pre-column derivatization of the amino acids witho-phthaldialdehyde andN-isobutyryl-L-cysteine followed by high-performance liquid chromatographic separation and fluorescence detection of the isoindol derivatives formed. The following most abundant D-AA were found (highest and lowest absolute and relative amounts): D-Ser (379.8 — 30.1µMol/L; 56.5 — 19.0%), D-Ala (53.8 — 7.6µMol/L; 19.6 — 5.7%), D-Thr (5.8 — 0.25µMol/L; 3.4 — 1.0%), D-Val (3.7 — 0µMol/L; 4.2 — 0%), and D-Phe (3.5 — 0.35µMol/L; 4.8 — 1.4%).
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 22-28 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Chiral separation ; Capillary column ; 2,6-Di-O-pentyl-3-O-propionyl-γ-cyclodextrin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary 2,6-Di-O-pentyl-3-O-propionyl-γ-cyclodextrin has been synthesized and used for enantiomer separation in capillary gas chromatography. Experimental results showed that the stationary phase has good enantiomer selectivity toward amino acids, amines, alcohols, diols, epoxides, and lactones,etc. 2,6-Di-O-pentyl-3-O-propionyl-γ-cyclodextrin has good thermal stability: the highest recommended temperature isca 170°C.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Pentachlorophenol residues ; Off-flavours ; Wines and corks ; Electrolytic conductivity detector/mass spectrometry ; detectors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A gas chromatographic methodology with selective detection is presented for the analysis in wines and corks of pentachlorophenol residues, which are suspected to be the most likely precursors of some off-flavours described in several wine samples. After derivatisation, pentachlorophenol acetate residues were monitored by electrolytic conductivity detection and/or mass spectrometric detection in the selective ion mode at m/z 264 and 266. Recoveries varied from 80 to 96% for wine samples fortified with 5 to 100 μg l−1 and from 83 to 91% for corks (fortified at 25 to 100 μg kg−1). The proposed methodology allowed for a determination limit of μg l−1 for wine and 10 μg kg−1 for corks.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 475-478 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Phenolic acids ; Olive and elm tree tissues ; Soil phenolics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A method for the separation of phenolic acids along with shikimic and quinic acids by means of capillary gas chromatography is described and discussed. The method involves the previous derivatization of the acids to trimethylsilyl derivatives and it has been applied to the separation of acids extracted from olive leaves and roots, elm leaves and a soil A horizon. Quite good results were achieved both from qualitative and quantitative points of view. Qualitative differences have been pointed out in the phenolic acid composition of two olive cultivars and between leaves and roots of the same cultivar; also two elm species can be discriminated on the basis of the phenolic acid content.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Porous polymer stationary phase ; Selectivity studies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The behaviour of GC columns packed with the copolymer of methacrylic ester of p,p'-dihydroxydiphenylpropane diglicydyl ether and divinylbenzene was studied. Selectivity studies were made for three polymer samples of different molar ratio of monomers. To determine the selectivities of these copolymers retention indices for seven test compounds in comparison to those obtained on Porapak Q are calculated. Additionally, the efficiency of porous polymer purification was studied by a SFE-GC-MS technique.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 595-598 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Chiral / enantiomeric separation ; Amphetamine ; Methamphetamine ; Cyclodextrin-derivatized phases
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Enantiomeric separation of amphetamine and methamphetamine as achiral derivatives on 2,6-di-O-pentyl-3-O-trifluoroacetyl-β-cyclodextrin, 2,6-di-O-pentyl-3-O-trifluoroacetyl-γ-cyclodextrin and 2,6-di-O-pentyl-3-O-propionyl-γ-cyclodextrin stationary phase in capillary gas chromatography is described. Trifluoroacetic anhydride and acetic anhydride were used as derivatizing reagents. Excellent precision was obtained for concentrations down to 0.1% / e.e. On 2,6-di-O-pentyl-3-O-propionyl-γ-cyclodextrin the elution order of R,S-amphetamine was reversed when the derivatizing reagent was changed but could not be reversed on any of the other phase types.
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  • 7
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Nitrogen phosphorus detection ; Atrazine and simazine ; Freeze-dried water analysis ; ELISA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The determination of atrazine in freeze-dried water samples containing simazine, 0.6% glycine as stabilizer and other pesticides has been compared using three different techniques: (i) direct rapid-magnetic particlebased ELISA, (ii) dichloromethane liquid-liquid extraction (LLE) and Florisil column clean-up prior to ELISA determination and (iii) LLE, Florisil column clean-up and gas chroamtography with nitrogen phosphorus detection (GC-NPD). The methodology developed in this paper has shown the advantages of the introduction of a clean-up step prior to ELISA determination and its correlation with GC-NPD determinations. Atrazine could be determined at levels between 0.1 to 5 μg l−1 in water smaples using the different methods described in this paper. The crossreactivity problems found in the ELISA test associated with the presence of simazine are also discussed.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 71-73 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Spectinomycin ; Silylation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A gas chromatographic assay for spectinomycin hydrochloride is described. The method is based on that prescribed by the United States Pharmacopeia (USP XXII). The method involves silylation of spectinomycin hydrochloride; phenazone is used as an internal standard. Spectinomycin and phenazone have adequate stability under the prescribed conditions. The stationary phase is 3% OV-17 on Gaschrom Q 100–120 mesh. The selectivity of the proposed method is better than that of the GLC method described in the USP XXII.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Enantiomer separation ; Permethylated cyclodextrin stationary phases ; Side-chain fluorinated alkylbenzenes ; Thermodynamic data
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The separation of racemic side-chain fluorinated alkylbenzenes and bromofluorinated analogues by capillary gas chromatography using permethylated α, β and γ-cyclodextrins dissolved in polysiloxanes of different polarity as stationary phases is described. The influence of the achiral polysiloxane matrices on the separation of enantiomers is discussed in the light of the results obtained with the different phases. For a part of the tested compounds thermodynamic data are determined which describe the interaction of enantiomers with the stationary phase. The mechanism of separation is discussed on this basis and by comparison with data for structurally similar compounds.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 355-362 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Method validation ; Reggedness test ; Residual solvents
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Ruggedness testing is performed on a gas chromatographic method for the quantitative determination of residual solvents in steroids. Eight experimental variables or factors which were expected to influence the quantitative results were selected. These factors were divided into two independent groups, i.e. four factors related to the injection process and four factors related to separation and detection. In order to determine interaction between factors and quadratic effects, a central composite design was selected for the set-up of the experiments. Because in the method an internal standard is used, relative peak area was used as response. A deviation of up to 2.5% per factor for the quantitative results was regarded as acceptable. Other responses studied are related to the system suitability. Observed main, quadratic and interaction effects were translated into rugged intervals of the experimental variables by graphical presentation. It was found that besides main effects significant interaction effects were present, for example between the temperature of the injector and the split-flow. Interaction effects can easily result in the reduction of the rugged intervals by a factor of 2. The calculated rugged intervals were compared with the precision of the instrument or factor settings in order to estimate the ruggedness of the factors. Eventually, the maximum effect of the variation in the instrument settings on the quantitative results regarding the precision of the factor settings was found to be only 2.2%. Overall, the method proved to be rugged for most factors, except for the split-flow of the injector for which the method was only rugged to a limited extent.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 438-442 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Retention/structure and retention/temperature ; relationships ; Experimental design ; Enthalpy-entropy compensation ; para-Hydroxy benzoic esters
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An experimental design has been used to study the effect of column temperature on the gas chromatographic retention of eightpara-hydroxy benzoic esters. A rapid procedure has been developed to reduce the number of experiments compared with traditional methods. Capacity factors were determined and the enthalpy and entropy of transfer from the mobile phase to the stationary phase, ΔHo and ΔSo, respectively, were calculated using the linear Van't Hoff equation (dependence of ln k′ on 1/T). A retention prediction system (RPS) for these compounds in GC was investigated. The molecular connectivity index was used to describe the quantitative structure relationships. Enthalpy — entropy compensation revealed that the mechanism was similar for all the compounds studied.
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  • 12
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Priority pollutants ; EPA methods ; Unleaded gasoline ; Volatile organochlorine compounds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The complete separation of the sixty volatile organochlorine (VOC) priority pollutants has been achieved by coupling two different liquid-modified adsorption chromatography columns. Two temperature programs were used to obtain the complete separation in a relatively short analysis time. Detection was by FID alone
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 93-97 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Retention index ; Adsorption effects ; Terpene alcohols ; Fused-silica capillary columns
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Retention indices of 6 selected hydroxy compounds (aliphatic and bicyclic alcohols, phenols) were determined on 2 HP-5 fused-silica, capillary columns with different film thicknesses (0.11 μm and 0.33 μm) at 8 different oven temperatures between 80 and 150°C. For some substances the I-T plot was found to show a minimum which cannot be explained by the common retention-index temperature-dependence in gas-liquid chromatography. This result is discussed in terms of adsorption at the liquid-solid interface of the capillary column.
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  • 14
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Stationary Phase and solute polarity ; Molecular structural coefficients ; Retention index ; Takács equation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Molecular structural coefficients, Sc, for one hundred solutes have been calculated by means of the Takács equation using retention data obtained with over fifty stationary phases, SP. Employing data of seven SP's (characterized in our laboratories) it was found that the variation of Sc with column temperature was linear for most solutes. With data of n-decane and the ten McReynolds probes on up to fifty SP's of polarity less than RP=72, at 120°C, it was found that the Sc of n-decane and cis-hydrindane decreased slightly with increasing SP polarity, while the Sc of non-alkanes remained constant or increased very little as the SP polarity increased. The points for n-decane fit well to a second order polynomial. Again using a temperature of 120°C, the increments of Sc for solutes belonging to an homologous series were correlated with the polarity of SP's. Reasonably straight lines were obtained for all the chemical functions studied, Sc increasing with increasing SP polarity.
    Materialart: Digitale Medien
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  • 15
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Stationary phase characterization ; Principal component analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary In this study, several new stationary phases were characterized by principal component analysis. Fourteen new stationary phases, including substituted phenyl and oligoethyleneoxide functionalities on polysiloxane polymers, were tested and compared to three well known stationary phases. The main features of these phases were studied using a series of test solutes of varying chemical characteristics representing the data set for principal component analysis. Two principal compounds were found to account for 99.20% of the variance (the first accounted for 94.96% and the second for 4.24%). The data were represented as a two-dimensional map for visual representation of the characteristics of these stationary phases. The first principal component represented a selectivity based on polarity (r2=0.998), while the second showed Lewis acid-base characteristics of the phases. Polarizable and amphoteric characteristics of these phases also became evident using this evaluation method.
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  • 16
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Liquid-liquid extraction ; Supercritical fluid extraction ; Pesticides ; Freeze-dried water
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The stability of freeze-dried water samples spiked with eight agrochemicals (atrazine, simazine, linuron, carbaryl, propanil, fenitrothion, parathion and fenamiphos) were examined to evaluate their suitability as candidate reference materials for their determination in water samples. In addition, two different extraction procedures, liquid-liquid and supercritical fluid extraction, were compared for the isolation and trace enrichment of target analytes from freeze-dried water samples. Final analytical determinations were by gas chromatography-nitrogen phosphorus detection and electronic impact mass spectrometry, and by liquid chromatography-diode array detection. The whole methodology developed in this paper permitted the determination of pesticides spiked in water at levels varying from 0.03 to 6.9 μg L−1.
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 624-628 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Ion-trap detection ; Nitriles ; Cerelas ; Perfluoroacylation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Bromoxynil and ioxynil have been determined inplants and soil by gas chromatography. These herbicides are extracted from soil samples with methylene chloride at acidic pH. Plant samples are extracted with a basic acqueous solution and extracts purified by solvent partitioning. Herbicide residues are submitted to perfluoroacylation prior to GC separation. These compoiunds are determined by ion-trap detection with single ion monitoring; N-(3-chloro-4 methyl-phenyl_ perfluoropropyl amide is used as internal standard. The detection limit of the method is near 0.001 μg g−1 for the samples studied. The proposed methods are sensitive and reproducible enough to allow determination of these herbicides at residue levels in plants and soil.
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 11-14 
    ISSN: 1612-1112
    Schlagwort(e): Supercritical fluid extraction (SFE) ; Gas chromatography ; Pesticide residues ; Oxadixyl
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary This work describes the study of a degradation curve of Oxadixyl in field-treated potato and tomato samples. The residues were extracted using classical and supercritical fluid (SFE) extraction methods and analyzed by HRGC/ECD. The extraction techniques were compared and the results indicate the advantages of using SFE as an alternative method for pesticide analyses in these samples.
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 706-712 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Short chain fatty acids ; Intestinal fluids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The quantification of short chain fatty acids in their free form, by gas chromatography, is the method of choice provided that the underivatized acids elute with good peak shape and reproducibility. In biological samples not only the highly polar acids themselves but also deposits of nonvolatile sample components may interact with the column or the packing material. As a result, the peak symmetry of the fatty acids and their reproducibility can become increasingly poor. Reduction of the nonvolatile matrix components by filtration of the sample has been examined in order to achieve direct analysis of the short chain fatty acids in intestinal samples by packed column GC. Membrane filter units (0.8 μm) allow a quick and simple filtration of the samples. This pretreatment reduces the peak tailing and the broadening of the peaks. The method, when applied to different intestinal samples, allowed the quantification of short chain fatty acids in hundreds of samples without derivatization. Good results are obtained at sample concentrations higher than 0.2 mmol l−1 for each acid.
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 224-227 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; C1−C4 alkyl tert-butyl ethers ; Retention index
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The separation of C1−C4 alkyl tert-butyl ethers with the general formula (CH3)3C−O−R (R-alkyl substituent) on fused-silica capillary columns coated with dimethylsilicone and cyanopropylmethylsilicone stationary phases was investigated. Retention indices were determined at two temperatures in order to understand their chromatographic behaviour. The respective standard deviations were 0.3 and 0.5 i.u.
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  • 21
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Organonitrogen pesticides ; Organophosphorus pesticides ; Apples ; Solvent extraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A gas chromatographic method employing a capillary column and a selective nitrogen/phosphorus detector (NPD) has been developed for the determination of organophosphorus (OP) and organonitrogen (NP) pesticides in horticultural samples (apples). The separation of sixteen pesticides and the internal standard was performed in thirteen minutes. The analytical characteristics of the method, including linear response ranges, detection limits, and reproducibility, have been studied using a 1∶1 mixture of ethyl acetate and xylene as extraction solvent. The possibility of mutual interference between pesticides has also been studied. A procedure for the quantitative extraction of the sixteen pesticides from apple samples has also been developed; for fifteen of the pesticides recoveries 〉85% were obtained after 90 minutes extraction. The effect of different solvents both on recovery and on the sensitivity of the subsequent chromatography were also investigated. It was found that the sensitivity required must be considered when the solvent for sample treatment is selected.
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 419-426 
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Gas chromatography ; Chirasil-Val ; Amino acid enantiomers ; N-Isobutyryl-cysteine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Free D-amino acids (D-AA) were detected as native constituents in juices of vegetables (cultivars of cabbage, tomato, carrot, garlic) and fruits (organes, clementine, grapefruit, lemon, apples, pear, grapes) using gas chromatography (GC) or high-performance liquid chromatography (LC). For investigation by GC, AA enantiomers were converted into theirN(O)-pentafluoropropionyl 2-propyl esters and resolved on a Chirasil-L-Val capillary column. For determination by LC, precolumn derivatization of AA enantiomers usingo-phthaldialdehyde together with the chiral thiolsN-isobutyryl-L-cysteine orN-isobutyryl-D-cysteine and fluorescence detection of the diastereomeric isoindole derivatives, resolvable on an octadecylsilyl stationary phase, were used. D-Ala (0.6–3.8%) was detected in all freshly pressed plant juices usually in the highest relative amounts. Other D-AA detected were D-Asx (0.1–1.9%), D-Glx (0–1.3%), D-Ser (0–1.7%), D-Arg (0.4–1.2%, in grapes, orange, grapefruit, and clementine) and D-Leu and D-Val (1% in cabbage). Absolute amounts of native D-AA were totally 28–57 μmol L−1 in fruit juices, 14.5 μmol L−1 in a tomato juice and 8.5 μmol L−1 in a carrot juice.
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  • 23
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Correlation chromatography ; Simulation model ; Adsorption effects ; Separation improvement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Experiments and simulations prove that correlation chromatography can greatly reduce the disadvantage of a non-linear response of the chromatographic column. A factor that has been accepted as being an important source of error in correlation or multiplex chromatography, has been shown not to be. Separations affected, improve dramatically when correlation chromatography is used, and a substantial amount of correlation noise only arises when there is a large difference in separation between a conventional chromatogram and a correlogram. A model has been developed for simulating these nonlinearities. It is shown that, especially for correlation chromatography, the simulation results match the practical measurements very well.
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 694-700 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; PTV injection system ; Aqueous samples ; Pesticides ; Breakthrough volumes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A GC method is described for the determination of pollutants in aqueous samples by direct enrichment out of large sample volumes in a PTV injector. The vaporized water is eliminated through the split vent and the analytes are concentrated on an adsorbent inside the insert of the PTV. For the selection of suitable adsorbents, breakthrough volumes of selected pesticides and nitroaromatics on Tenax TA, Tenax GR, Chemipack C18 and graphitized carbon blacks have been determined by experiment. The determination of the breakthrough volumes was carried out directly in the PTV insert. Tenax TA proved to be the best sorbent with regard to the breakthrough volumes and its inertness to the analytes to be determined. As the result of the investigations, 500 μl of aqueous standard solutions of pesticides and nitroaromatics (concn.=0.02 ... 2 μg/l) were analyzed with an average relative standard deviation of 10%. The procedure was successfully applied for the analysis of real samples.
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 191-198 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Reversed-flow technique ; Absorption rate ; Air pollutants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A simple chromatographic method is developed to determine the rate constant for expulsion of an air pollutant from water or its diffusion parameter in the liquid, the rate constant for chemical reaction of the pollutant with water, its mass transfer coefficient in the liquid, and the partition coefficient between liquid water and air. From these physicochemical parameters, the absorption rate by sea water and, therefore, the depletion rate of a polluting substance from the air can be calculated, together with the equilibrium state of this absorption. The method has been applied to nitrogen dioxide being absorbed by triple-distilled water and by sea water, at various temperatures. From the temperature variation of the reaction rate constant and of the partition coefficient, the activation energy for the reaction and the differential heat of solution were determined.
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 645-648 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Headspace analysis ; Gonadotrophins ; Residual solvents
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A headspace, gas chromatographic method for determining residual solvents in pharmaceutical products such as the gonadotrophin powders, has been developed. The method allows the determination of residual solvents by transferring the samples directly into a vial contianing 10 mL 2M sodium chloride; the analysis is carried out by sampling the headspace and separating by capillary gas chromatography using a programmedtemperature vaporizer (PTV) injector. The procedure described is simple, sensitive and reproducible. The lower limit of detection is 20 ppb for ethyl alcohol, 8 ppb for acetone and 0.5 ppb for diethyl ether.
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 210-215 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Correlation chromatography ; Concentration methods ; Polymer dynamic head-space sampling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Gas chromatography has been used to study the kinetics of evolution of volatiles from polypropylene samples (at 70°C). Correlation chromatography (CC) and the trapping of volatiles on Tenax sorbents and activated charcoal were employed to improve the detector signal. As a reference, the kinetics of gas evolution was studied by making a series of direct single injections of polymer head-space gas on a GC column. The results of trapping differed from those obtained by single injection. However, the data from single injections and CC were in good agreement. The CC method was found to offer far more operator convenience for dynamic head-space analysis than sample trapping, being less subject to operator errors.
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 265-270 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Triglycerides ; Packed vs. capillary columns ; Milk fat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Quantitative gas chromatography of triglycerides in conjunction with established triglyceride formulae can be used to determine various milk fat parameters. Since the evaluation of, for example, iodine number or content of non-milk fats (foreign fats) in milk fat requires only the separation of triglycerides by carbon number and since repeatabilities, especially of the highboiling triglycerides, have been less acceptable with capillary columns in the past, packed columns have been used exclusively. There is, however, an increasing demand for the use of capillary instead of packed columns and to that end the present investigation has been carried out. To achieve a suitable resolution, with this particularly exacting high-temperature application, a short 5 m capillary column of extreme temperature stability has been used. As well as modification of various analytical conditions different injection techniques have been investigated. On-column, PTV and split injection were compared with regard to repeatability. The cold-on-column injection technique was found to produce the best results, being comparable to the excellent precision of a packed column. Thus, a method is now available by means of which the determination of milk fat parameters by the triglyceride formulae, such as the amount of foreign fats in milk fat, can now be carried out with a standardized capillary column.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 363-365 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Light hydrocarbons ; Stabilized crude oil ; Capillary guard column
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary This paper reports a quick, and simple method for quantitative determination of C2 to C6 hydrocarbons in stabilized crude oil without using a back flush system. A mixture of crude oil and internal standard is injected into a GC equipped with a 6 meter length of fused silica capillary as a guard column. The light hydrocarbons are separated individually up to the last peak of the hexane group with the heavier components trapped in the guard column. The total analysis time for each sample is 15 minutes. The base line is table for up to 15 consecutive analyses. The guard column and the injector port are then reconditioned by simply heating them for one hour at 300 °C.
    Materialart: Digitale Medien
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  • 30
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Liquid modified adsorption capillary columns ; Polar compound analysis ; Aqueous solution analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The preparation of graphite layer open tubular (GLOT) columns is described together with their application to the analysis of priority pollutants and polar compounds such as alcohols, free carboxylic acids, aliphatic amines and phenols at the sub-nanogram level. A specific application of GLOT columns is for the direct analysis of aqueous solutions avoiding solvent extraction procedures. Several chromatograms of critical separations are reported together with calibration curves. A study of the reproducibility of column preparation is reported in terms of the standard deviation of the capacity ratio and of the minimum HETP obtained.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 679-688 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Stationary phases ; Phase constants ; Explanatory coefficients
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Explanatory phase coefficients according to Abraham et al. are calculated from McReynolds index differences and the phase constant B. The retention expression (log Vg)−A=BI/100 connects specific retention volumes and retention indices. McReynolds phase constants and Abrahams explanatory coefficients can be used with similar accuracy for the prediction of relative retention data and for the characterization of stationary phases in gas chromatography. The application of polarity constants for the characterization of stationary phases is discussed.
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  • 32
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Gas chromatography ; Particle beam MS detection ; Polycyclic aromatic metabolites ; Biodegradation in water
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Two liquid chromatography-particle beam mass spectrometry (LC-PBMS) systems have been used for analysis of polycyclic aromatic hydrocarbon metabolites in water samples from a biological decomposition model experiment. The results were compared with those obtained by classical gas chromatography-mass spectrometry. Evaluation of spectral data indicated the presence of six main metabolites; 1H,3H-naphtho [1,8-cd]pyran-1,3-dione, 1-(hydroxymethyl)naphthalene, and 1,2-acenaphthenedione were identified by use of standard substances and spiking experiments. Enrichment of the investigated water samples with online pre-column (C18) concentration, freeze-drying, and solvent extraction led to similar results with only slight differences. The application of microbore separation columns proved to be a promising tool in particle beam LC-MS measurements.
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 151-157 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; C5−C12 hydrocarbons in air ; Cryogenic focussing ; Thermal desorption
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A homemade cryogenic system derived from readily available material is described, illustrating its usage as an accessory for adsorption/thermal desorption chromatography. A small Chromsorb-W-HP packing (1 cm) was introduced into a deactivated precolumn as a cryofocussing, preconcentrating unit. This was able to retain the analyte which had been thermally desorpted from a Tenax TA sampling tube at a relatively higher temperature (−80°C∼−90°C), with the analyte also reinjected on the analytical column in a relatively narrow band. Average overall recoveries for 24 hydrocarbons tested were 97.5%. Cryofocussing enhanced sensitivity and improved resolution. Field studies at a petroleum industry site were carried out and the accessory proved to be useful for complex C5−C12 hydrocarbon analysis in ambient air.
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 304-312 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Electron capture detector ; Theoretical model of ECD
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary This paper reports a theoretical model of the ECD detector. The model presented here can be used to examine the influence of pulse parameters on the current and signal characteristics of the detector. On the basis of this model it was found that a space charge is created in the detector when it is supplied with pulse voltage. Due to the electric potential generated by the space charge, in the time between the pulses the electrons and negative ions move towards the detector electrodes. The ionization current of the detector is the sum of the electron current flowing to the anode under the influence of the supplied pulse voltage and the current flowing under the space charge potential in the time between the pulses. It was also found that the detector signal is the sum of the differences between those two currents caused by introducing the sample molecules to the detector. The model was tested for a detector with different electrode configurations which worked at temperature of 300 K or 573 K and which was supplied with nitrogen or Ar+10% CH4 as the carrier gas.
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  • 35
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Adsorption and partition columns in series ; Molecular sieves ; Isomers of benzene homologs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The possibility of using short gas chromatographic columns packed with different molecular sieves (silicalite and aluminophosphates), showing definite selectivity to para-isomeric compounds, in series with columns containing a liquid stationary phase was investigated. The molecular sieves were of different origin, while 1,2,3-tris (2-cyanoethoxy)propane (TCEP) and polyethylene glycol adipate (PEGA) were used as the liquid stationary phase. Ortho-, meta- and para-isomers of xylene, chlorotoluene and dichlorobenzene were chromatographed on these columns. It is shown that the best separation is obtained on a combined column with silicalite containing pure silica gel as the molecular sieve, and 10% PEGA as the liquid phase. Molecular sieves of aluminophosphate origin show only weak selectivity toward the para isomers.
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 39 (1994), S. 294-298 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Preconcentration ; Thermal modulator ; Cross-correlation ; Trace analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The inside wall of an uncoated polyethylene capillary traps organic substances from a water sample pumped through it by a nitrogen gas stream. Heating the capillary in a chromatographic oven slowly releases the trapped organic substances from the wall. Nitrogen carrier gas transports sample substances released through a thermal desorption modulator and onto a chromatographic column. Pulsing the temperature of the modulator modulates the concentrations of sample components as they enter the column. Computing the cross correlation of the detector output signal against the applied modulation signal generates the chromatogram. Detection limits below 1 ppb are possible using a flame ionization detector. No sample pretreatment or cold trap is required.
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 689-693 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Enantioselectivity ; GC-MS ; GC-GC-MS ; Pinus peuce ; Monoterpenes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Needles of the Macedonian Pine,Pinus peuce Griseb., a conifer growing in the Balkan mountains, were extracted by a Likens-Nickerson simultaneous distillation-solvent extraction device. The components of this essential oil were identified by the retention times obtained on two columns differing in polarity and by GC-MS. Because of the complex nature of such plant extracts, a multidimensional GC method for enantiomer analysis, using a non-chiral pre-column and a chiral main column has been developed. The enantiomeric ratios of five monoterpene hydrocarbons were estimated by GC-GC and GC-GC-MS.
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 38 (1994), S. 173-176 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Chiral phases ; Phenylalanine tetraamides ; Amino acids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A wide series of L-phenylalanine tetraamide selectors (Phe-n-O-TA) have been synthesized and used as stationary phases for chiral resolution of D,L-amino acids by capillary gas chromatography. The influence of length and polarity of the oxaalkanoyl bridge spacing the diamide chains of the selectors and the effects of steric hindrance on separating power were investigated. The characteristics of the chiral columns and the separation factors of D,L-n-butyl-N-trifluoroacetyl amino esters are reported.
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  • 39
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Curie-point pyrolysis ; Multivariate analysis ; Sodium dodecylbenzene sulfonate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Multivariate analysis was used to develop a viable method for determination of sodium dodecylbenzene sulfonate (DBS) by Curie-point pyrolysis gas chromatography. The pyrograms obtained were normalized against a maximum peak area and peak height. Normalized values were used for Quantification IV, which is one of the multivariate analysis methods, to select useful values initially. Then cluster analysis was carried out using both the selected values and their deviations. This method corresponds to qualitative analysis and indicates which data-base is similar to the sample. On the basis of this data-base, calibration data-bases are chosen. Principal component analysis (PCA) was performed using the calibration data-base and a set of sample data simultaneously. The principal component scores and contribution coefficients obtained were used to construct a calibration curve from which the DBS content of the sample was calculated. The results are in fair agreement with theoretical values.
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  • 40
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Morpholine ; Hydrazine ; Boiler feed water and steam condensates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Hydrazine, an oxygen scavenger in boiler water, was derivatised to the corresponding acetone azine and determined at the ng ml−1 level by gas chromatography. Morpholine, a corrosion inhibitor used in steam boilers, was estimated either directly (if 〉2.0 μg ml−1) or by quantitative preconcentration (0.1 ng – 2.0 μg ml−1). To obtain symmetrical peaks for these amines, the column packing was coated with KOH. Use of a nitrogen-specific detector improved accuracy of estimation of hydrazine and morpholine, giving a RSD of 1.9–3.6%. Chromatographic analysis of these amines in boiler feed water and steam condensate samples collected from boilers servicing a petroleum refinery is described. Environmental safety regulations calls for monitoring of hydrazine and the methods developed can easily be adapted for this purpose.
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  • 41
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; MSD, ECD and NPD ; Non-steroidal anti-inflammatory drugs (NSAIDs) ; Plasma samples
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The aim of this work was to compare the performance of the MSD, ECD and NPD systems when used for drug assay in biological fluids. As a practical test, six non steroidal anti-inflammatory drugs added to plasma samples were detected and quantified. The analyses were carried out after solvent extraction from an acidic medium and subsequent methylation. The linearity of response was tested for all the detection systems in the range of 1 to 25 ng/ml. Precision and accuracy were determined at 1, 5 and 10 ng/ml. The minimum quantifiable level for the six drugs was about 1 ng/ml with each of the three detection systems.
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  • 42
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 411-414 
    ISSN: 0935-6304
    Schlagwort(e): Size exclusion chromatography ; Gas chromatography ; Coupled LC-GC ; Cleanup and analysis ; Automation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A fully automated on-line sample cleanup system based on the coupling of size exclusion chromatography to high resolution gas chromatography is described. The transfer technique employed is based on fully concurrent solvent evaporation using a loop-type interface, early vapor exit and co-solvent trapping. Optimization of the LC-GC transfer was done visually via an all-glass oven door. To circumvent the problem of mixing within the injection loop, an adaptation was made to the standard loop-type interface. The determination of a series of additives in a polymer matrix is presented as one example of the vast range of applications opened up by this technique.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 43
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 821-826 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Atomic emission detection (AED) ; Programmed temperature vaporization (PTV) ; Nitro musks ; Human adipose tissue ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Atomic emission detection (AED) has been successfully applied to the determination of nitro musks in the fat of human adipose tissue by gas chromatography at trace concentration levels. Element specific detection with the AED combined with a clean-up procedure for nonpolar substances makes target screening analysis for lipophilic nitro aromatic compounds possible for the first time. The lack of sensitivity, especially in the AED nitrogen and oxygen trace, was compensated by higher concentration of the extracts and injection of larger sample volumes performed by cold programmed temperature vaporization (PTV) in the solvent split mode. The combination of the superior quantification properties of the atomic emission detector with large sample volume introduction makes the quantification of nitro musks down to the ppb level possible. All five nitro musks investigated exhibit linear dynamic ranges going down close to instrumental limits of detection. Moreover, organochlorine compounds could be sensitively detected in the same sample extract by the AED chlorine trace without any interferences from coeluting matrix compounds.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 44
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 17 (1994), S. 457-462 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Flame photometric detector ; Pyrolyzer ; Sulfur boiling point distribution ; Light cycle oils ; Exponential dilution flask ; Low sulfur diesel ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A method has been developed to determine the boiling point distribution of sulfur compounds in light cycle oils (LCO'S). The method chosen for this analysis was GC with a flame photometric detector (FPD) and pyrolyzer. Tests were carried out to evaluate the recovery efficiency, repeatability, and accuracy of the method. Repeatabilities within 2% were obtained. The recovery of benzothiophenes and dibenzothiophenes was close to 100%; this was important because these are the major sulfur components in LCO's. No hydrocarbon or solvent interferences were observed with the use of the pyrolyzer, even for a 95% solvent level. Comparison with results from other techniques showed that the method accurately determined the levels of sulfur compounds in the LCO boiling point range.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 78 (1982), S. 170-175 
    ISSN: 1432-2072
    Schlagwort(e): Acetylcholine ; Choline ; Soman ; Organophosphate ; Anticholinesterase ; Toxicity ; Lethality ; CNS ; Brain areas ; Rats ; Gas chromatography ; Mass spectrometry ; Time course ; Cholinergic function
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The time course of changes in rat brain levels of acetylcholine (ACh) and choline (Ch) was investigated following a single SC injection of soman (0.9 LD50, 120 μg/kg) to understand the relationship between central neurotransmitter alteration and soman toxicity. Of the animals exposed to the dose of soman, 46% died within 24 h, with maximum mortality occurring during the first 40 min following soman administration. In a second group, surviving rats were killed at various times after treatment by a beam of focused microwave radiation to the head, and ACh and Ch levels were determined by gas chromatography-mass spectrometry. Soman produced a maximal ACh elevation in the brain stem at 20 min (34.4%), in cerebellum at 40 min (51.9%), in cortex and striatum at 2 h (320.3% and 35.2%, respectively), and in hippocampus and midbrain at 3 h (94.5% and 56.8%, respectively). ACh levels remained above normal approximately 30 min in the brain stem; 2 h in the midbrain, cerebellum, and striatum; 8 h in the cortex; and 16 h in the hippocampus. Ch levels were elevated in all areas except the striatum. Ch maxima occurred at 10–40 min and returned to control levels approximately 3 h after injection. Results suggest that perturbation of ACh levels due to soman was not uniform throughout the brain and that soman toxicity may reflect ACh changes in multiple areas, rather than changes in any given area. These data further suggest a possible relationship between elevated Ch levels and soman toxicity.
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Research in experimental medicine 181 (1982), S. 19-25 
    ISSN: 1433-8580
    Schlagwort(e): Gas chromatography ; Serum level ; Azathioprine ; 6-Mercaptopurine ; Immunosuppression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The knowledge of serum levels of azathioprine or its metabolite 6-mercaptopurine is important for the monitoring of the immunosuppressive therapy after kidney transplantation, especially when kidney function is low. For this reason, the work of Bailey et al. was modified. 6-Mercaptopurine was extracted from the serum with a mixture of isopropanol-ethylacetate (1:1 v:v), derivatized with trimethylaniliniumhydroxyde and measured gaschromatographically. Sulfhydryl-protecting reagents were added to prevent loss of substance. Oxyethyltheophylline was used as the internal standard. The extraction and clean-up method recovered 80% of the 6-mercaptopurine present, the lower limit of sensitivity was 20 ng/ml, i.e., ten times lower than that of Bailey et al. The method could be realized on eight patients treated with azathioprine, the half life of the drug was about 20–40 min within the first hour after i.v. application.
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 321 (1982), S. 293-297 
    ISSN: 1432-1912
    Schlagwort(e): Alcoholism ; Cerebrospinal fluid ; Ethanol ingestion ; Gas chromatography ; Mass spectrometry ; 5-Hydroxytryptophol ; Urine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The serotonin metabolite 5-hydroxytryptophol was determined in cerebrospinal fluid and urine of alcoholics and healthy subjects, by a glass capillary gas chromatographic-mass spectrometric method. The urinary excretion rate (14.6±2.9 pmoles/μmoles creatinine) and urine (109±20 pmoles/ml) and cerebrospinal fluid (4.12±0.21 pmoles/ml) concentrations in healthy subjects were established. Only 1% of the 5-hydroxytryptophol in urine occurred in free form. Ethanol ingestion (80, 120 g) by healthy subjects lead to a 20–100-fold increase in the urinary excretion rate of 5-hydroxytryptophol. In cerebrospinal fluid the increase was about 60%. Alcoholics had increased urinary excretion rates and cerebrospinal fluid levels during intoxication, which were in the same range as in intoxicated healthy subjects. During recovery from intoxication, the 5-hydroxytryptophol level in alcoholics decreased, but the CSF levels were still higher than in healthy subjects.
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  • 48
    ISSN: 1612-1112
    Schlagwort(e): Teflon capillary columns ; Chemically modified teflon ; Gas chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The preparation of teflon capillary columns employing direct coating of the stationary phase to the chemically modified teflon surface and the role of the chemically modified teflon in the separation mechanism are described. Two types of contributions from the modified teflon have been observed: nonspecific adsorption of the carbon surface and specific interactions of polar groups in the carbon skeleton. The use of polar liquid phases can eliminate adsorption due to the presence of polar groups in the modified teflon.
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 16 (1982), S. 60-62 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Amines ; Derivatization ; Chloroformate esters
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The gas chromatographic analysis of amines after conversion to electron capture sensitive carbamates in two-phase systems has been studied. Hydrophilic compounds, for instance methylamine, are reacted with 2,2,2-trichloro-tert. butyl chloroformate. Quantitation below 10−7 M can be made by thermionic or electron capture detection. A hydrophobic amine, namely N,N-dimethyl-n-octylamine, was derivatized with 2,4,6-tribromophenyl chloroformate with addition of iodide ion to the aqueous phase. The favorable effect of iodide ion as well as the choice of pH and chloroformate ester is discussed.
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 16 (1982), S. 98-102 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Rectangular channel ; Efficiency ; Capacity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Gas chromatographic experiments have been performed in a truly rectangular channel with a 60∶1 cross-sectional aspect ratio, constructed according to the field-flow fractionation technology. It is shown that the peak broadening is controlled by the thickness of the channel while the maximum load is determined by the largest cross-sectional dimension. However, even with its elongated configuration, the side walls contribute significantly to the band broadening of solutes with a high diffusivity. Good agreement is found between the experimental plate height data and the recent theoretical calculations of Golay [13] taking into account the side-wall effect.
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 704-706 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Isopropyliden-sorboses ; TMS-derivatives ; GC-MS combined technique ; Mass spectra
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A method has been developed using gas chromatography — electron impact mass spectrometry for the determination of the di-0-isopropylidene-sorbofuranose and mono-0-isopropylidene-sorbofuranose. The compounds are separated as their trimethylsilyl derivatives on a capillary column coated with the stationary phase SE-52. The mass spectra show that the silylation reaction is quantitiative and that the isopropylidene groups does not change.
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 183-185 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Analysis of ethylbenzene hydroperoxide ; Time normalization method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A gas chromatographic method, based on the time normalization technique, is described for the analysis of ethylbenzene hydroperoxide in mixtures containing ethylbenzene, acetophenone, 1-phenylethanol, benzaldehyde and phenol. Different liquid phases were tested and the best results were obtained with tricresyl phosphate and neopentyl glycol sebacate. The influence of the support, the liquid loading and the gas velocity are discussed.
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 625-630 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Open-tubular (capillary) columns ; Comparison of liquid phases ; Influence of temperature ; Retention index data
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The influence of temperature and liquid phase film thickness of open-tubular (capillary) columns on the retention index values of hydrocarbons on methylsilicone liquid phases is discussed. Data obtained on methylsilicones and squalane are compared. Retention index values of 43 hydrocarbons between 40 and 70 °C on OV-101 liquid phase are listed.
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 351-354 
    ISSN: 1612-1112
    Schlagwort(e): Supported catalysts ; Reserved-flow GC ; Drying step ; Gas chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Application of reversed-flow gas chromatography to study the drying step in the preparation of supported catalysts is proposed. It is demonstrated that this technique can be applied to investigate the kinetic law followed, as well as to obtain kinetic parameters of drying (rate constants, activation energies and frequency factors). Amaterial illustrating this application is γ-Al2O3 impregnated with usual organic solvents (n-C5H12,n-C6H14,n-C7H16, CH3COCH3 and CH3CH2OH). It was found that in all cases above a simple first-order law based onone kind of active site is followed. Moreover, it was observed that the activation energyE a of the drying process increases almost linearly with the relative molecular mass of the solvent, whereas for the same solventE a increases with the amount used. The operation of a kinetic compensation effect suggests “similar” activated complexes of the various solvents used.
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  • 55
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Fused silica capillaries ; New polar phases: OV-1701 and RSL-310 ; Immobilization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The possibilities of OV-1701 and RSL-310, two new stationary phases, have been evaluated for capillary gas chromatography in fused silica columns. OV-1701 is a cyanopropylphenyldimethyl polysiloxane of moderate polarity possessing excellent chromatographic characteristics. The phase exhibits high coating and chromatographic efficiencies, high temperature stability and is suitable for cross-linking. RSL-310 is a polar liquid stationary phase yet to be permanently bonded in a capillary column. The selectivity of both phases extends the applicability of fused silica columns.
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  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 241-244 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Monosaccharides ; Polyols ; GC of TMS derivatives
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary This paper describes the gas chromatographic separation of the mixture of isopropylidene monosaccharides, and their trimethylsilyl derivatives. Based on the total analysis time and resolution the best stationary phase was SF-96 using Chromosorb G as the solid support and temperature programming.
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 312-314 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Injection-port modification ; Oxygen and nitrogen traces
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The paper presents a new device modifying normal injection port of a gas chromatograph for eliminating air contamination thus enabling determination of traces of oxygen or nitrogen. Further modification is also proposed which enables the analysis to be carried out with a limited quantity of sample gas. Potential application of this device in the analysis of reactive gases like florine has been indicated.
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  • 58
    ISSN: 1612-1112
    Schlagwort(e): Phthalides ; Gas chromatography ; Chromosorb W ; Isomerization ; Ligustilide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary During GLC of naturally occurring mixtures of phthalides on packed columns an artefact was sometimes detected that originated from Z-ligustilide. Active sites of Chromosorb W were responsible for the formation of the artefact, that was assumed to be E-ligustilide as GC-MS revealed that its mass spectrum was identical with that of Z-ligustilide. No isomerization was observed when freshly coated Chromosorb W was used or the support was deactivated by benzoyl chloride or melamine. The identity of the artefact was confirmed by UV irradiation experiments.
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 30-32 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Arsenic ; Inorganic materials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A method is described for the quantitative chlorination and extraction of arsenic as arsenic trichloride from a number of alloys. The conditions for the quantitative gas chromatographic measurement of the volatile chloride have been studied. The proposed method for inorganic materials is very fast giving results within 10 min; sensitive, 1.5·10−13 g As can be detected, simple and accurate. At the ng level of As the error is about 20% with a standard deviation less than 20%, and at the 10pg level the error is about 36% with a standard deviation of 44%.
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 765-768 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Preparative scale chromatography ; Capacity ; Dual-stage separation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The capacity of different versions of single- and dual-stage separation of mixtures on a preparative scale is considered. It has been shown that dual-stage separation with intermediate condensation considerably enhances the capacity of the installation as compared with a single-stage process.
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 117-124 
    ISSN: 1612-1112
    Schlagwort(e): Various packed GC column ; Gas chromatography ; Porous layer beads ; GC/MS analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Theoretical comparisons of various packed GC column types are presented with respect to analysis time, efficiency, sample dilution, and sample capacity for a given maximum inlet pressure. In particular, totally porous particles, porous layer beads, and glass beads are compared with one another. It is shown that 30 μm porous layer beads offer a useful compromise between analysis time and plate count with relatively good sample capacity. Moreover, when using 1 mm i.d. columns (microbore), outlet flow rates that are reasonable for direct coupling to magnetic sector mass spectrometers are achieved making these columns suitable for GC/MS. Using 30 μm Zipax porous layer beads, columns yielding 8,000 to 10,000 plates/meter have been produced with inlet pressures of 13 to 26 atm. A simple modification of the injection port converts the maximum inlet pressure of a commercial gas chromatograph to 26 atm. With such pressures, columns in excess of 20,000 plates can be achieved. Chromatograms are presented illustrating the promise of these microbore columns for GC and GC/MS analysis.
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  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 245-248 
    ISSN: 1612-1112
    Schlagwort(e): Chromatoscopy ; Gas chromatography ; Graphitized carbon black ; Molecular structure and retention ; Aromatic hydrocarbons
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A molecular-statistical calculation of the retention volumes at zero sample size on graphitized thermal carbon black is carried out for quasi-rigid molecules of fluorene, indene, 1-methylindene, 2-methylindene and three dimethylindenes. A reasonable agreement is observed between the calculated and the available experimental gas chromatographic data. The potential barrier to internal rotation and the torsional angle in styrene molecules are estimated by comparing theoretically calculated and measured retention volumes.
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  • 63
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Silicone liquid phases ; Oxidation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The on-column oxidation of apolar and polar silicones used as gas chromatographic stationary phases is investigated. Even at 225° the effects of oxidation are found to be slight. Of the materials investigated the methylphenylsilicones are the most stable.
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  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 505-508 
    ISSN: 1612-1112
    Schlagwort(e): Glass capillary ; Gas chromatography ; Methyl chloroacetates ; Methyl chloropropanoates ; Methyl chlorobutanoates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The gas chromatography of all chlorinated methyl acetates, methyl propanoates and methyl mono- and dichlorobutanoates has been studied on Carbowax 20M and SE-30 glass capillary columns under various running conditions. The order of elution on a non-polar column was largely determined by the boiling point of esters, whereas on a polar column it was much influenced by the structure of compounds. Complete separation of the combined mixture of all 27 compounds could not be achieved, however, methyl 3,3-dichlorobutanoate was the only ester overlapped on both columns in spite of the various column temperatures used. The best separation of the mixture was on Carbowax 20M with a temperature program from 50°C at 8°C/min, isothermal running conditions leading either to poor separation of volatile components or long analysis time and broad peaks of higher chlorinated esters. The relative retention times for compounds at the various column temperatures are given and the retention order on a polar and on a non-polar column discussed.
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  • 65
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 517-520 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Carbon-silica adsorbents ; n-Octadecanol film ; Phase transitions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The properties of the n-octadecanol film on carbon-silica adsorbent (Carbosil) were investigated. It was found that n-octadecanol forms an oriented film on the Carbosil's surface. If the surface of the basic silica gel is not completely covered with carbon, then the phase transition takes place in this film at a temperature higher than the melting temperature of n-octadecanol. One may distinguish two forms of this film, characterised by the different structures and the temperatures of the phase transitions. The first exists on the surface of silica gel unblocked by carbon. This part of the film is a monolayer, in which the alcohol molecules are vertically oriented. The solid compact-liquid expanded type phase transition at the well-defined temperature occurs in this film. In the second part of the film formed on the carbon surface, there is a multilayer of n-octadecanol. Its molecules are probably parallely oriented in relationship to the adsorbent surface. This film desintegrates progressively when the temperature increase. Maximum temperature of this phase transition is lower than the temperature of its analogue on pure silica gel surface.
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 546-558 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Capillary columns ; Quantitative analysis ; Sample inlet systems ; High-speed analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The attainment of precise quatitative analytical data using open-tubular (capillary) columns in standard, commercially available gas chromatographic instrumentation is demonstrated. Key elements in the design and proper utilization of the instrumentation are discussed. The function of the various sample introduction systems is elaborated and their quantitative performance demonstrated. The extra-column contribution to band-spreading is determined and the resultant data is used assessing the suitability of commercial instrumentation for highspeed capillary gas chromatography. The quantitative analysis of a sample containing some eleven components in less than thirty seconds is shown.
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  • 67
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Crystal hydrates as stationary phases ; Mobile Phases containing water ; Selective retentions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The use of crystallohydrates, crystallohydrate solutions and melts as stationary phases in gas chromatography has been proposed. Crystallohydrates have been shown to display high selectivity in the separation of polar organic compounds when use is made of water vapours as the mobile phase. Some aspects of gas-liquid chromatography in water vapours and with the stationary phase comprising crystallohydrates have been studied, and the preliminary results obtained point to the desirability of further progress in this field.
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  • 68
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 16 (1982), S. 201-203 
    ISSN: 1612-1112
    Schlagwort(e): Phenols ; Whisky ; Gas chromatography ; Aroma compounds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Twelve volatile phenols were identified in whisky by combined gas chromatography-mass spectrometry. Of these phenols 2,4-dimethylphenol was found for the first time in the aroma of whisky. The content of phenol, o-, m-, and p-cresol, guaiacol, p-ethylphenol, p-ethylguaiacol and eugenol in whiskies originating from different countries was determined by gas chromatography as their 2,4-dinitrophenyl ethers using electron capture detection. The results show that Scotch whiskies differ from others in the content of o-, m-, and p-cresol. The odour threshold values of phenols studied were determined in a 10% (v/v) ethanol-water mixture and in some cases also in the whiskies. Cresols have been found to make contribution to the aroma of Scotch whisky.
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  • 69
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 16 (1982), S. 26-31 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Ionization detectors ; Gaia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary This paper is an account of the development of the gaia hypothesis as seen through the eyes of a gas chromatographer. Gaia is a radical notion about the Earth which postulates the climate and chemical composition to be regulated at an optimum by and for life. Gas chromatography played an important role in the gathering of evidence for the hypothesis but most significantly the art of inventing detectors lead to the developement of a planetary life detector through which gaia was revealed.
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  • 70
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 16 (1982), S. 282-285 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Naphtha analysis ; Gasoline analysis ; Hydrocarbon type analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Two different gas chromatographic methods are used for the determination of hydrocarbon type distribution in naphtha and gasoline samples with final boiling points up to 275 °C. The methods are based either on a single capillary column or on a valve-switched packed column system. Both methods give extensive information on paraffins, olefins, naphthenes and aromatics in total as well as by carbon-number. In each case the analysis is fully automated with a computer controlling the entire analysis from injection to results presentation. The advantages and limitations of both methods are discussed.
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  • 71
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 16 (1982), S. 322-324 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Graphitized carbon black supports ; Determination of hydroxyacids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Acid-washed graphitized carbon black (Carbopakc B) modified with trimesic adic and PEG 20M has proved to be effective for quantitative analysis of underivatized low molecular weight hydroxyacids. Calibration data revealed good linear relationships between relative peak area and concentration for lactic and 3-hydroxybutyric acids down to 0.05 mmol/l. The packing material was suitable for the analysis of aqueous solutions of hydroxyacids as it is tolerant to injections of water over a prolonged period of use. The GC system developed has been applied to the analysis of some hydroxyacids of biomedical interest in blood plasma and lactic acid contained in wine and beer.
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  • 72
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Modified thermal energy analyzer ; Selective detection of nitrogen compounds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A modification to the TEATM Analyzer is described, which allows it to be used as a highly selective GC detector for nitrogen compounds as well as for N-nitrosamines and nitro compounds. The modified Analyzer is as sensitive as the AFID, but has a much higher selectivity towards nitrogen compounds than the AFID. Its response appears to be molar, with an output that is dependent only on the number of nitrogen atoms present. The performance of the modified Analyzer for the analysis of ammonia, amines,N-nitrosamines, nitriles and organonitro compounds is reported and discussed, as is its application to the detection of these compounds in bacon and beer samples.
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  • 73
    ISSN: 1612-1112
    Schlagwort(e): Graphizized carbon black traps ; Organic air pollutants ; Work areas ; Gas chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The use of traps containing graphitized carbon black for the collection and pre-analysis of atmospheric pollutants in industrial areas is presented. The working conditions, in terms of trapping capability and effectiveness of release by thermal desorption are discussed. Some practical applications are also given.
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  • 74
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Van der Waals' volume ; Polarity of stationary phase ; Retention index
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Equations for Retention Index (I) versus Van der Waals, volume (Vw) on squalane are studied for alcohols, carbonyls, esters and ethers. Each equation includes linear and branching substances with different positions of the functional group in the carbon chain. The study is extended to stationary phases with polarities from 4.29 to 91.54 on the Tarjan et al. scale. Variations of the slope and origin ordinate values with the polarity of the stationary phase are discussed.
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  • 75
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 125-132 
    ISSN: 1612-1112
    Schlagwort(e): Capillary columns ; Fast analysis ; Gas chromatography ; Instrumental effects ; Optimization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The efficiency of fast GC columns depends largely on the quality of the chromatograph. A theoretical and experimental study shows the relative importance of the various phenomena involved and permits the optimization of a GC System. Extremely good performances, exceeding 2,500 plates per second have been routinely obtained.
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  • 76
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 180-182 
    ISSN: 1612-1112
    Schlagwort(e): Acidic fermentation products ; Characterisation ; Gas chromatography ; Methyl esters
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A rapid and simple method for the identification of acidic fermentation products is described. Methyl esters of volatile and non-volatile acids are separated on a single chromatographic column. Retention time data for a number of acids are tabulated.
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  • 77
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 521-524 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Retention index ; Connectivity index ; Van der Waals' volume ; Alkanes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The relationships between retention index and Van der Waals' volume and between retention index and connectivity index have been studied for 58 different alkanes (C1−C9) on squalane. The correlation coefficient for the former is higher than for the latter. From these equations a linear relationship between Van der Waals' volume and connectivity index is obtained which indicates that the two parameters are equivalent. A simple method for calculating the Van der Waals' volume of alkanes is proposed.
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  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 569-574 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Capillary columns ; Fused silica capillaries ; Capillary drawing ; Glass capillaries
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A compact description is given of a simple and reliable method of drawing flexible fused silica capillary for gas chromatography. Some emphasis is given to the fact that the practices of drawing optical fibres should not be followed too slavishly so this leads to unnecessarily complicated and expensive equipment. Satisfactory capillary column silica tubing can be made with straightfoward extension of the method developed earlier for drawing thick walled capillary. A simple glass/silica hydrogen oxygen diffusion flame bumer is described for fusing the preform tubing at the draw point which is enclosed by a water cooled glass enclosure to trap evaporated silica and maintain the operation under dust free conditions. The uniformity of the capillary diameter is better than 5% which is adequate for most gas chromatographic purposes. The second part of the paper yet to be published will cover the methods developed for coating the capillary both internally and externally.
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 16 (1982), S. 107-111 
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Thermionic ionization ; Catalytic flame ionization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A newly designed thermionic detector was operated in two modes of thermionic ionization detection (TID), and a third mode of catalytic flame ionization detection (CFID). Operating modes were varied by changing the composition of the electrically-heated thermionic/catalytic source, and the composition of gases supplied to the detector. A TID-2 source activated by a low concentration of Cs/ceramic was operated in a dilute H2/air environment and provided specific responses to nitrogen and phosphorus compounds. A TID-1 source activated by a high concentration of Cs/ceramic was operated in a N2 environment and provided very high specificities and picogram detectivities to compounds containing electronegative functional groups such as the NO2 group. A CFID source formed from Ni/ceramic was operated in a H2/air flame environment and provided universal responses to all organics with enhanced responses to some heteroatom compounds.
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  • 80
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 382-384 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Trapping by active charcoal ; Thermal desorption system ; Microwave oven ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 81
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 50-51 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass, fused silica ; Connection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 82
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, fused silica ; Effluent splitter ; Selective detectors: NPD, Hall™ electrolytic conductivity detector ; Chloro- and chloronitroanilines ; POTW sludge extracts ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Simultaneous detection with a 700-A Hall™ and an NPD detector is an effective technique for characterizing chloro-and chloronitroanilines in highly complex Publicly Owned Water Treatment Works (POTW) sludges. The utilization of a modified Varian effluent splitter and a SE-54 fused silica capillary column permitted the detection of mid-picogram quantities of the polar chloroanilines without sacrificing peak shape. The response of the Hall™ detector in the halogen mode was roughly proportional to the number of chlorine atoms present, while the response of the Hall™ in the nitrogen mode and the NPD was less predictably influenced by the presence of one or more nitro groups. When combined with retention time data, the ratio of the NPD response to the Hall™ response has been found to substantiate the presence of chloro- and chloronitroanilines in sludge extracts.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 83
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 98-99 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Polyaromatic hydrocarbons ; Airborn Particulates ; Aircraft turbines ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 84
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; High temperature silylation ; C2-C6 fatty acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 85
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 206-207 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; cis, trans, positional isomers of C22 esters separated on OV-73 ; Numerous arguments favor nonpolar columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 86
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 236-244 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary columns ; Rotary valve ; Cold trap ; Reinjection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: This paper describes a cold trap/reinjection system for capillary columns which utilizes a flow switching rotary valve. Sample enrichment is performed in a liquid nitrogen-cooled glass trap attached to the valve. Evaporation of enriched compounds is carried out with the aid of an electric heating coil. Parameters such as cryogenic trapping efficiency, reinjection rates, transference of sample, and adsorption, as well as overall performance, are examined. In addition, a comparison is made between the cold trap/reinjection technique and injection with a gas-tight syringe.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 87
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 265-266 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary column ; Helium ionization detector ; Aroma ; Coffee ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 88
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 45-47 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Fast screening of drugs and adulterants ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 89
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 55-56 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Non-uniformity of distribution of stationary phase confirmed ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 90
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 53-55 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, fused silica ; Thermal aging regeneration of fused silica capillaries ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 91
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary ; SD-E enrichment ; Pesticide residues ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A simple method is described for the quantitative determination of organochlorine pesticides and polychlorinated biphenyls (PCB's) in water at the sub-ppb level. A micro gas-phase extractor advantageously replaces other preconcentration and purification techniques. The extract is analyzed by capillary gas chromatography without further enrichment. The recovery at the ppb level was nearly 100% for organochlorine pesticides and more than 80% for PCB's. The complete procedure including sample preparation, steam distillation-extraction, and capillary gas chromatographic analysis is carried out in less than four hours.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 92
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 377-378 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Glass capillary columns ; Headspace analysis ; Alcohols in blood ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 93
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 165-166 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Pulse flow reaction chromatography ; Two-detector system ; Reactions in a two-detector system ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 321-321 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, fused silica ; Pyrolysis studies ; Cryofocusing device ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 95
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 80-84 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Triglycerides in cocoa butter, hazelnut oil ; Separation according to the number of unsaturated fatty acids (N.U.F.A.) ; Ozonolysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Structure determination of triglycerides according to their number of unsaturated fatty acids (N.U.F.A.) is more easily achieved after ozonolysis of their mixtures (fats and oils) than by capillary gas chromatographic analysis of the mixture as such. Analyses performed before and after ozonolysis of cocoa buttel, hazelnut oil, and a mixture of both fats illustrate the potential of this approach to the structure elucidation of triglycerides by chromatographic techniques.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 96
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 156-157 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary column ; Cold trapping ; Use of ABT concept in evaluating effect of trapping on peak ; shape ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 175-181 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary columns ; Discrimination factor non-vaporizing on-column/vaporizing splitless injection for underivatized steroids ; Quantitation feasible for most underivatized steroid hormones except corticosteroids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Recent developments in the preparation of capillary columns by persilanization of the glass surfaces have resulted in highly inactive, heat-stable columns. With this type of column certain steroid hormone classes can be analyzed without derivatization; these include the 17-keto steroids, 11-oxo compounds, estrogens, and progesterone metabolites. It has been found that good quantitative analysis calls for non-vaporizing, on-column injection, as normal vaporizing injection results in breakdown of thermolabile compounds such as estriol and 17-OH progesterone metabolites. The gas chromatographic method described was used to obtain urinary steroid profiles.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 208-209 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Liquid chromatography ; Capillary glass ; Capillary columns with inside splitting of eluent ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 211-212 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; On-column injection ; Elimination of discrimination ; Sliding sample inlet ; Cooling column system ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 107-108 
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Static coating ; Closing glass capillaries ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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