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  • 2000-2004  (5)
  • 1970-1974  (7)
  • Gas chromatography
  • Nuclear reactions
  • 1
    Electronic Resource
    Electronic Resource
    Identification of rumanite (Romanian amber) as thermally altered succinite (Baltic amber) (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 665-678 
    Details
    ISSN: 1432-2021
    Keywords: Key words Amber ; Rumantite ; Succinite ; Pyrolysis ; Gas chromatography ; Mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  Romanian amber (rumanite) has been considered to be a separate species of fossil resin for more than a century. While earlier investigators held it to be very similar to succinite (Baltic amber), modern scholars have assigned it a distinctly different botanical origin. We have found that almost all of the constituents of the ether-soluble fractions of 13 specimens of authentic rumanite identified by gas chromatography–mass spectrometry have previously been reported in the soluble fraction of succinite, including succinic acid and its monoterpene esters. Additionally and significantly, the soluble fraction of rumanite contains a number defunctionalized compounds that do not preexist in succinite, but that are produced by pyrolysis of whole succinite or of its insoluble polymeric fraction. Simultaneous methylation pyrolysis–gas chromatography–mass spectrometry of the polymeric fraction of seven of the rumanite specimens yielded further copious amounts of dimethyl succinate, a number of diterpene resin acid methyl esters, and additional defunctionalized compounds known to be pyrolysis products of succinite. The evidence shows conclusively that the botanical origin of rumanite is not distinct from that of succinite. Rather, rumanite is a succinite that has suffered partial thermal degradation in the course of the folding of the Oligocene Kliwa sandstone formation in which it is most commonly found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690000111
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  • 2
    Electronic Resource
    Electronic Resource
    Isolation and identification of odorants generated in wine during its oxidation: a gas chromatography–olfactometric study (2000)
    Springer
    European food research and technology 211 (2000), S. 105-110 
    Details
    ISSN: 1438-2385
    Keywords: Key words Wine ; Flavor ; Oxidation ; Aroma ; Gas chromatography ; olfactometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The changes in the flavor profiles of several white wines undergoing oxidation were monitored through gas chromatography–olfactometry (GCO). The study showed that up to 19 odorants were generated during wine oxidation, and that several of the odorants originally present in the wine disappeared or decreased. An aroma extract dilution analysis revealed that 5 of these 19 odorants have maximum dilution factors, and that a second group of 7 may have some sensory significance as well. The isolation and identification of the different odorants was achieved via normal and reverse-phase high-performance liquid chromatography and high-resolution GCO. The impact odorants of oxidized wine were found to be 2, 4, 5-trimethyldioxolane, methional (methylthiopropanal), sotolon (4,5-dimethyl-3-hydroxy-2(5H)-furanone), eugenol (4-propenyl-2-methoxyphenol) and an unknown compound with mass spectrum similar to methylvanillate. Other odorants also formed during wine oxidation were 1-octen-3-ol, t-2-nonenal, furfural, benzaldehyde, 2-butoxyethanol, acetovanillone and a dioxolane isomer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002179900128
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of nitric oxide metabolites by means of the Griess assay and gas chromatography–mass spectrometry in the cavernous and systemic blood of healthy males and patients with erectile dysfunction during different functional conditions of the penis (2000)
    Springer
    Urological research 28 (2000), S. 364-369 
    Details
    ISSN: 1434-0879
    Keywords: Key words Nitric oxide metabolites ; Erectile dysfunction ; Griess reaction ; Gas chromatography ; Mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recent research implicated that the relaxation of cavernous arterial and trabecular smooth muscle – the crucial event in penile erection – is initiated by the release of nitric oxide (NO) from nerve terminals within the cavernous tissue as well as from the endothelia that line the lacunar spaces and the intima of penile arteries. The present study was undertaken to determine whether plasma levels of the NO metabolites nitrate (NO− 3) and nitrite (NO− 2) in the systemic and cavernous blood of male subjects change during different penile conditions, and whether there is a difference in the NO− 3 and NO− 2 levels of normal males and patients with erectile dysfunction (ED). Twenty-four potent adult male volunteers and 15 patients with ED were exposed to visual and tactile erotic stimuli in order to elicit penile tumescence and, in the group of healthy volunteers, rigidity. Whole blood was aspirated from the corpus cavernosum and the cubital vein, and NO− 3 and NO− 2 levels were determined in plasma aliquots by means of the Griess reaction and a method combining gas chromatography and mass spectrometry (GC-MS). The mean systemic and cavernous plasma NO3 −/NO2 − level in blood samples obtained from the healthy volunteers was 25–31 μM when determined by means of the Griess reaction and 37–41 μM when measured by GC-MS. Both approaches revealed that NO3 −/NO2 − levels in the peripheral and cavernous blood do not change appreciably during developing erection, rigidity and detumescence. Moreover, no significant differences were found between NO3 −/NO2 − plasma levels in the systemic and cavernous blood samples taken from the normal subjects and patients during penile flaccidity, tumescence and detumescence. Our results may reflect the fact that NO metabolism in the corpora cavernosa in the phases of penile tumescence and rigidity may account for only a minor fraction of local levels of NO3 − and NO2 −, which may also derive from exogenous sources. Moreover, the basal levels of NO metabolites in the blood flushing the lacunar spaces of the cavernous body in the state of developing erection could conceal any release of NO that may occur within the penile tissue. Thus, we conclude that the quantification of NO metabolites by means of advanced detection methods, such as GC-MS, is of no use in the workup of ED.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002400000141
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  • 4
    Electronic Resource
    Electronic Resource
    Solution-Phase Synthesis of Mixed Amide Libraries by Simultaneous Addition of Functionalities (SPSAF) to a Diketopiperazine Tetracarboxylic Acid Scaffold Monitored by GC Analysis of Isobutyl Alcohol (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1669-1675 
    Details
    ISSN: 1434-193X
    Keywords: Combinatorial chemistry ; Amides ; Gas chromatography ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A symmetric diketopiperazine scaffold 2 has been prepared in a very simple two-step procedure from L-aspartic acid dimethyl ester. This product (a tetracarboxylic acid equally protected at the two symmetric positions) has been employed as a template for the synthesis of mixed amide libraries in the solution phase using the SPSAF (simultaneous addition of functionalities) strategy. By judicious choice of the amines employed, it is possible to prepare parallel libraries containing hundreds of products using just a small number of different amines. We have also developed a simple method for monitoring the required conversion of the acid into amides based on an assay of the amount of iBuOH (determined by GC) formed during the coupling mediated by isobutyl chloroformate. We have observed that a conversion higher than 90% (iBuOH by GC) guarantees correct formation of the desired amides. This indirect method for assessing the conversion in a combinatorial reaction employing mixed reactants (SPSAF) can conveniently be used for the routine determination of libraries prepared in the solution phase. In a broader perspective, the present results contribute as a further step in the development of new and simple systems for monitoring the progress and evolution of combinatorial reactions
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Note on the Net Retention Volume in Chromatography with a Real Gas as a Carrier (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 119-126 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; retention volume ; real gas carrier ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problem of the calculation and interpretation of the net retention volume with a real gas as carrier is revisited. The properties of the carrier are described by a first order virial equation of state. The net retention volume of a solute is related to the mean flow rate of the carrier, therefore determination of the mean flow rate of a real gas carrier is reviewed. It is shown that the mean flow rate cannot be calculated from the mean column pressure. With a real gas carrier the local capacity factor depends on the local pressure of the real gas. The basic relationship between the net retention volume and the function describing this pressure dependence is also reviewed. Precise formulae as well as practical approximations are presented for the calculation of the mean flow rate, of the mean column pressure, and of a representative pressure related to the mean capacity factor.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    A new gas chromatographic method for determination of mandelic acid in urine (1974)
    Springer
    International archives of occupational and environmental health 33 (1974), S. 163-167 
    Details
    ISSN: 1432-1246
    Keywords: Styrene-mandelic acid ; Polyester resin work ; Gas chromatography ; Urinalysis of styrene metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new GLC method for analysis of urinary mandelic acid as trimethylsilyl derivative was developed. The method was applied to the urine of plastic workers exposed occupationally to various concentrations of styrene. When compared with a colorimetric method the GLC method appeared to be superior in both sensitivity and specificity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00538915
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  • 7
    Electronic Resource
    Electronic Resource
    Measurement of chloral hydrate, trichloroethanol, trichloroacetic acid and monochloroacetic acid in the serum and the urine by gas chromatography (1974)
    Springer
    International archives of occupational and environmental health 33 (1974), S. 49-58 
    Details
    ISSN: 1432-1246
    Keywords: Assay of trichloroethylene metabolites ; Monochloroacetic acid ; Trichloroacetic acid ; Methyl esterification ; Gas chromatography ; Electron-capture detector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A gas chromatographic method for the determination of trichloroethylene metabolites in the serum and the urine is described. The trichloroethanol glucuronide in the urine was hydrolyzed to trichloroethanol by Β-glucuronidase. After an extraction with ethyl ether, the extract was dried at 20
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00538979
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  • 8
    Electronic Resource
    Electronic Resource
    A comparison of the effect of a suppository and two douches on vaginal malodorants (1973)
    Springer
    Archives of gynecology and obstetrics 215 (1973), S. 245-262 
    Details
    ISSN: 1432-0711
    Keywords: Vaginal odorants ; Gas chromatography ; Odor assays ; Olfactronics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Gas-chromatographic odor-assay techniques have been used to study vaginal odors. An improved version of this technique was applied to compare the efficacy of a suppository containing phenylmercuric acetate, a feminine douche preparation, and a conventional vinegar douche in reducing the concentrations of malodorants in the vaginal vapors of ten normal women. Seven malodorants occurred frequently in vaginal vapors; seven more were noted less frequently, and additional ones occurred occasionally. A reduction in the malodorant concentrations was observed with all treatments, but this effect reached acceptable statistical probability levels,p〈0.05 (95% confidence levels), consistently only for the suppository. The effect of the phenylmercuric acetate suppository on the concentration of vaginal malodorants was statistically valid at 2, 6, and 10 hours after its use. In the case of the douche preparation, the degree of reduction in the malodorant concentrations did not reach statistical significance. A Sign Test, however, on the frequency of the malodorant concentration decreases as compared with the frequency of malodorant concentration increases indicated statistical significance for the decreases at 6 and 10 hours after the use of the douche preparation. The total number of malodorants per sample likewise tended to decrease with the various treatments, but this effect reached statistical significance only for the suppository 6 and 10 hours after the treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00672809
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  • 9
    Electronic Resource
    Electronic Resource
    Metabolism studies of chlormethiazole by gas chromatography-mass spectrometry (1973)
    Springer
    International journal of legal medicine 73 (1973), S. 225-233 
    Details
    ISSN: 1437-1596
    Keywords: Chlormethiazole, metabolites ; Gas chromatography ; Mass spectrometry, chlormethiazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Description / Table of Contents: Zusammenfassung Die Metabolitprodukte von Chlormethiazol wurden aus der Leber extrahiert und mittels Dünnschichtchromatographie isoliert. Es wurden Chlormethiazol und drei andere Produkte nachgewiesen, wobei ein Produkt schon vorher als 4-Methyl-5-β-hydroxy-ethylthiazol identifiziert wurde. Die Strukturformeln für die zwei anderen Produkte wurden vorgeschlagen. Ein vierter Metabolit (4-Methyl-5-thiazolessigsäure) wurde aus Urin erhalten. Die Proben wurden durch Gaschromatographie, Gaschromatographie-Massenspektrometrie und durch hochauflösende Massenspektrometrie analysiert.
    Notes: Summary The metabolic products of chlormethiazole were extracted from liver and isolated by thin layer chromatography. Chlormethiazole and three other products were obtained. One of these was identified earlier as being 4-methyl-5-β-hydroxy-ethylthiazole and now structures are proposed for the other two. A fourth metabolite, 4-methyl-5-thiazoleacetic acid, was formd in urine. The samples were analyzed by gas chromatography, gas chromatography-mass spectrometry and by high resolution mass spectrometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02116826
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  • 10
    Electronic Resource
    Electronic Resource
    Gaschromatographisches Verfahren zur Bestimmung des Kohlenmonoxidgehaltes im Blut (1972)
    Springer
    Archives of toxicology 29 (1972), S. 325-330 
    Details
    ISSN: 1432-0738
    Keywords: Gas chromatography ; Carbon Monoxide ; Blood-Iron ; Gaschromatographie ; Kohlenmonoxid ; Blut-Eisen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird ein Verfahren zur Kohlenmonoxidbestimmung im Blut angegeben, das besonders für forensische Zwecke bei faulem oder stark denaturiertem Blut, aber auch für arbeitsmedizinische Probleme geeignet ist. Der gaschromatographische Nachweis des Kohlenmonoxids ist eindeutig. Der CO-Hb-Gehalt des Blutes errechnet sich aus der Eisenkonzentration der Probe und der festgestellten Kohlenmonoxidmenge. Die gegenüber spektralphotometrischen Untersuchungen längere Arbeitszeit wird durch die höhere Sicherheit und Beweisfähigkeit der Methode, insbesondere im Bereich geringer Konzentrationen, aufgewogen. An Brandleichen erhobene Befunde dürfen nur unter Berücksichtigung der Vorgeschichte interpretiert werden.
    Notes: Abstract A method for the analysis of carbon monoxide in blood is discussed; it is particularly suitable for forensic application using decayed or denaturated blood, and also for problems in industrial medicine. Gas chromatographic analysis of carbon monoxide gives reliable results. The content of CO-Hb is calculated from the iron concentration of the sample and the amount of carbon monoxide. This method takes longer than spectrophotometric examination, but is more accurate, particularly with low concentrations. Results in blood taken following death by burning can be interpreted only in the light of the history.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326648
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  • 11
    Electronic Resource
    Electronic Resource
    Data Processing in Gas Chromatography (1972)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 11 (1972), S. 366-375 
    Details
    ISSN: 0570-0833
    Keywords: Gas chromatography ; Computer chemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197203661
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  • 12
    Electronic Resource
    Electronic Resource
    Measurements of cardiac output in maximum exercise. Application of an acetylene rebreathing method to arm and leg exercise (1971)
    Springer
    European journal of applied physiology 29 (1971), S. 159-172 
    Details
    ISSN: 1439-6327
    Keywords: Maximum cardiac output ; Acetylene rebreathing ; Arm ergometry ; Gas chromatography ; Maximum oxygen intake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An acetylene rebreathing technique suitable for the measurement of cardiac output in maximum exercise is described; results have a coefficient of variation of 2.9–3.6%, and show good agreement with observations made by other methods during arm and leg work. Gas samples are analysed by gas chromatograph, using silica gel and molecular sieve/glass columns. Recirculation of the foreign gas is avoided by collection of the final gas sample after 7 sec of rebreathing. Allowance is also made for other systematic errors, including the dead space of the sampling needles and solution of gas in the lung parenchyma. Arm work has a similar oxygen cost to leg work if extraneous movements are avoided; however, the maximal attainable oxygen intake is less in arm exercise (28% in 5 young men). The heart rate in sub-maximum effort is 36–39 beats/min greater for arm work; however, the maximum heart rate is unchanged. The cardiac stroke volume is 25% smaller for both sub-maximum and maximum arm work, while the arterio-venous oxygen difference is slightly greater than in leg work. Both stroke volume and arterio-venous difference increase somewhat between 60 and 100% of aerobic power, but the main burden of increasing oxygen transport is accepted by the increase in heart rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698024
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