Gas-liquid Chromatography System Research Articles

Routine detection and identification in urine of stimulants and other drugs, some of which may be used to modify performance in sport.

Abstract A general procedure for the analysis in urine of basic drugs (and their metabolites), some of which may be misused as stimulants in sport, has been developed. The techniques used include gas-liquid and thin-layer chromatography and linked gas-liquid chromatography—mass spectroscopy. It is recommended that international control of drug-taking in sport be based primarily upon urine analysis by gas-liquid chromatography systems and also derivative formation followed by gas-liquid chromatography. The principles outlined in the procedure can be applied in a much wider forensic context.

Simulating Retention in Gas−Liquid Chromatography

Accurate predictions of retention times, retention indices, and partition constants are a long sought-after goal for theoretical studies in chromatography. Configurational-bias Monte Carlo (CBMC) simulations in the Gibbs ensemble using the transferable potentials for phase equilibria−united atom (TraPPE−UA) force field have been carried out to obtain a microscopic picture of the partitioning of 10 alkane isomers between a helium vapor phase and a squalane liquid phase, a prototypical gas-liquid chromatography system. The alkane solutes include some topological isomers that differ only in the arrangement of their building blocks (e.g., 2,5-dimethylhexane and 3,4-dimethylhexane), for which the prediction of the retention order is particularly difficult. The Kovats retention indices, a measure of the relative retention times, are calculated directly from the partition constants and are in good agreement with experimental values. The calculated Gibbs free energies of transfer for the normal alkanes conform to Martin's equation which is the basis of linear free energy relationships used in many process modeling packages. Analysis of radial distribution functions and the corresponding energy integrals does not yield evidence for specific retention structures and shows that the internal energy of solvation is not the main driving force for the separation of topological isomers in this system.

Differential Characterization ofAgrobacteriumSpecies Using Carbon-Source Utilization Patterns and Fatty Acid Profiles

Pathogenic and nonpathogenic strains of Agrobacterium tumefaciens (i.e., biovar 1), A. rhixogenes (i.e., biovar 2), A. vitis (i.e., biovar 3), and A. rubi were tested for their ability to utilize 95 different carbon sources available in the GN Microplate system and analyzed for fatty acid content using the MIDI gas-liquid chromatography system. Several carbon sources were identified as being of diagnostic value. With the exception of the A, rubi strain, hydroxy-L-proline and i-erythritol were exclusively metabolized by A. tumefaciens and A. rhizogenes, respectively. Analysis of fatty acid composition confirmed that cis-vaccenic acid (18:1 ω cis) is the predominant acid in all the Agrobacterium strains [...]

Gas chromatographic study of the inclusion properties of dibenzo-24-crown-8 ether

The inclusion properties of dibenzo-24-crown-8 ether were studied in gas-solid chromatography (GCS) and gas-liquid chromatography (GLC) systems. Substances potentially capable of interacting with the cavity of the crown ether —homologous series of alkanes, alcohols, ethers, aromatics and halogenated hydrocarbons—were used as the sorbates and solutes. It was found that inclusion compounds are formed with methanol, ethanol, dichloromethane, trichloromethane, 1,2-dichloroethane, diiodomethane and the aromatic nucleus of aromatics under conditions used in the GSC system and with dichloromethane, trichloromethane, 1,2-dichloroethane, diiodomethane and the aromatic nucleus of aromatics in the GLC system.

Applications of cellular fatty acid analysis

More than ever, new technology is having an impact on the tools of clinical microbiologists. The analysis of cellular fatty acids by gas-liquid chromatography (GLC) has become markedly more practical with the advent of the fused-silica capillary column, computer-controlled chromatography and data analysis, simplified sample preparation, and a commercially available GLC system dedicated to microbiological applications. Experience with applications in diagnostic microbiology ranges from substantial success in work with mycobacteria, legionellae, and nonfermentative gram-negative bacilli to minimal involvement with fungi and other nonbacterial agents. GLC is a good alternative to other means for the identification of mycobacteria or legionellae because it is rapid, specific, and independent of other specialized testing, e.g., DNA hybridization. Nonfermenters show features in their cellular fatty acid content that are useful in identifying species and, in some cases, subspecies. Less frequently encountered nonfermenters, including those belonging to unclassified groups, can ideally be characterized by GLC. Information is just beginning to materialize on the usefulness of cellular fatty acids for the identification of gram-positive bacteria and anaerobes, despite the traditional role of GLC in detecting metabolic products as an aid to identification of anaerobes. When species identification of coagulase-negative staphylococci is called for, GLC may offer an alternative to biochemical testing. Methods for direct analysis of clinical material have been developed, but in practical and economic terms they are not yet ready for use in the clinical laboratory. Direct analysis holds promise for detecting markers of infection due to an uncultivable agent or in clinical specimens that presently require cultures and prolonged incubation to yield an etiologic agent.

Application of a gas-liquid chromatography system with α-cyclodextrin for monitoring the stereochemical course of β-pinene hydrogenation

Complete separation of a mixture containing two enantiomers of β-pinene and four stereoisomers of pinane was achieved by gas chromatography using α-cyclodextrin dissolved in formamide as the stationary phase. The developed method was utilized for the monitoring of the course of the catalytic hydrogenation of commercial (−)-β-pinene.

Simultaneous determination of organophosphorous pesticides in forensic chemistry by gas-liquid chromatography with hydrogen flame ionization detector.

The simultaneous determination of 45 organophosphorous pesticides (OP, 8 phosphates, 14 phosphorothioates, 15 phosphorodithioates and 8 miscellaneous OP), which were registered or had been registered in Japan, was performed by gas-liquid chromatography (GLC) with a flame ionization detector. Three kinds of liquid phases (2% OV-1, 1.5% OV-17 and 3% QF-1) under isothermal and temperature-programmed operations were employed for the detection of OP. The retention indices of 43 OP except ESP and trichlorfon were determined by GLC systems on OV-1 and QF-1, but 41 OP except ESP, trichlorfon, acephate and menazon on OV-17. The effectiveness for a series of GLC systems was evaluated by using the concept of discriminating power (DP). The highest DP for single GLC system was given by isothermal analysis on QF-1 (DP=0.931, numbers of OP=43 and error factor=50). The most effective DP for two GLC systems was given in combination with OV-1 and QF-1 with the temperature-programmed analyses (DP=0.980, numbers of OP=43 and error factor=50).

Gas-liquid chromatography system with α-cyclodextrin as an analytical tool for the studies of stereoselective hydrogenation of α-pinene

α-Cyclodextrin dissolved in formamide solution was applied as the stationary phase in gas-liquid chromatography for the enantio- and diastereoselective separation of α-pinene and pinanes. It was found that the stereoselectivity arising from inclusion of these compounds in α-cyclodextrin cavities is considerable. The method developed was used to monitor the stereochemical cource of α-pinene hydrogenation.

System evaluation and substance identification in systematic toxicological analysis by the mean list length approach.

In systematic toxicological analyses (STA), analytical methods are needed with a high Identification Power. The mean list length (MLL) approach, which is an improved and extended version of the Identification Power concept, provides an objective tool for the evaluation and optimum choice of analytical methods for STA. The MLL approach is elucidated and applied to the screening for basic drugs by thin layer chromatography (TLC) and gas-liquid chromatography (GLC). Its usefulness for TLC and GLC systems for the identification of these basic drugs has been evaluated for both single systems and combinations of systems. The MLL approach is also substance directed and can be applied to computerized data searches and substance identification. The method is applicable for single analytical systems and combinations of systems. Mixtures of substances can also be handled.

Separation of α- and β-pinene into enantiomers in gas-liquid chromatography systems via α-cyclodextrin inclusion complexes

Separation of α- and β-pinene into enantiomers in gas-liquid chromatography systems via α-cyclodextrin inclusion complexes

Mixed retention mechanisms in gas-liquid chromatography : II. Contributions of adsorption and partition to the retention volume in systems with polar solutes and non-polar stationary phase on a silanized support

The contributions from adsorption and partition at infinite and finite solute concentrations have been investigated for a gas-liquid chromatography system with a silanized support, non-polar stationary phase (octadecane) and polar solutes (ethyl methyl ketone and diisopropyl ether). It was found that the contribution from adsorption varied strongly with the sample size. The variation of adsorption with liquid loading at infinite solute concentration showed a rapid decrease between 0 and 1% loading followed by a rapid increase at ca. 5%. To explain this behaviour it is suggested that one part of the stationary phase is blocking the most active sites (dominating at very low liquid loading) and another part is forming droplets on the surface of the support. The variation of adsorption with liquid loading for loadings higher than ca. 2% can be explained by the variation of the gas-liquid interfacial area with liquid loading. It is therefore concluded that the dominant adsorption mechanism for loadings higher than ca. 2% is the adsorption at the gas-liquid interface.

Improved gas chromatographic analysis of fatty and resin acid mixtures with special reference to tall oil

Abstract and SummaryA gas liquid chromatography system for the analysis of complex mixtures of fatty and resin acids has been developed. On 30–40 m long, 0.3 mm ID glass capillary columns coated with 1,4‐butanediol succinate (BDS) and attaining over 90,000 effective theoretical plates, all main fatty and resin acids in wood extractives and various tall oil products can be separated and quantitatively determined without need of any prefractionation of the acids. Also the levopimaric acid is well separated. Retention values, including their temperature dependence, on columns coated with BDS or SE‐30 are given for 49 significant fatty and resin acids. Applications on wood extractives, sulfate soaps, and crude and distilled tall oil are presented and discussed.

Gas-liquid chromatography system with flame lonization, phosphorus, sulfur, nitrogen, and electron capture detectors operating simultaneously for pesticide residue analysis.

Gas-liquid chromatography system with flame lonization, phosphorus, sulfur, nitrogen, and electron capture detectors operating simultaneously for pesticide residue analysis.

Studies on steroids in urine of the male newborn.

Four different methods of isolation and purification were utilized to study steroids in urine of male newborns which was collected during the first 5 days of life. These methods included celite column, ion exchange column and thin-layer chromatography, solvolysis and enzyme hydrolysis with beta-glucuronidase and aryl sulfatase. Procedural losses were evaluated by using radioactive internal standards. Final quantitation of each steroid was achieved by comparison of its chromatographic and quantitative behavior with the respective standard steroids on various gas-liquid chromatography systems, either as parent compound or as trimethylsilyl ether derivative. The following steroids were found in the amounts indicated: progesterone, 2.1 mug/1 (pool I), 4.6 mug/1 (pool III); pregnanediol, 625.0 mug/1 (pool IIa), 605.0 mug/1 (pool IIb glucuronide), 25.4 mug/1 (pool IIb sulfate), 4.2 mug/1 (pool IIb free), 729.0 mug/1 (pool III); 16alpha-hydroxyprogesterone, 713.0 mug/1 (pool III), 16alpha-hydroxypregnenolone, 14,000.0 mug/1 (pool III); 16alpha-hydroxydehydroepiandrosterone, 2,350.0 mug/1 (pool III); 16-dehydroprogesterone, 155.0 mug/1 (pool I), 21.2 mug/1 (pool IIb glucuronide), 97.5 mug/1 (pool IIb sulfate), 5.3 mug/1 (pool III); 16-dehydropregnenolone, 382.0 mug/1 (pool I), 1,380 mug/1 (pool IIb glucuronide), 172.0 mug/1 (pool IIb sulfate), 174.0 mug/1 (pool III); 16-dehydropregnanolone, 8.3 mug/1 (pool I), 239.0 mug/1 (pool IIb sulfate). Pregnenolone, pregnanolone, 17alpha-hydroxyprogesterone and 17alpha-hydroxypregnenolone could not be detected. The results support the concept that the steroid patterns of urine of the newborn and amniotic fluid are very similar and that the amniotic fluid steroid content is mainly dependent on fetal urinary steroid excretion. The data on delta16-C21-steroids are discussed.

Inhibitory effects of aspirin and indomethacin on the biosynthesis of PGE 2 and PGF 2α

A gas-liquid chromatography system has been used to study the effects of indomethacin and aspirin on the biosynthesis of PGE 2 and PGF 2α by the prostaglandin synthetase system of bovine seminal vesicle. Both compounds were found to inhibit the production of PGE 2 and PGF 2α. However, based on statistical analyses, the inhibitory effect of indomethacin was found to be non-selective while aspirin produced statistically significant preferential inhibition of PGE 2 over PGF 2α.

Apparatus for the Detection of Radioactive Isotopes Attached to Material of Gas-Liquid Chromatography Systems Raymond M. Schiff (9 Henry Avenue, Park Ridge, N.J.) U.S. Pat. 3,290,501 (Dec. 6, 1966)

Apparatus for the Detection of Radioactive Isotopes Attached to Material of Gas-Liquid Chromatography Systems Raymond M. Schiff (9 Henry Avenue, Park Ridge, N.J.) U.S. Pat. 3,290,501 (Dec. 6, 1966)

Epitestosterone: Isolation from human urine and experiments on possible precursors

The isolation of the 17α-hydroxy epimer of testosterone from human urine is reported. The identity was proved by the absorption spectra in ethanol and in concentrated sulphuric acid and by its mobility and the mobilities of its products of acetylation and oxidation when chromatographed on thin layer, paper and gas-liquid chromatography systems. The evidence suggests that the urinary epi testosterone originates from androstenedione and from some other precursor by a pathway not including the peripheral metabolism of androstenedione.