Gas-liquid Chromatographic Separation Research Articles

Gas-liquid chromatographic separation of ceramides as di- O-trimethylsilyl ether derivatives

Gas-liquid chromatographic separation of ceramides as di- O-trimethylsilyl ether derivatives

Gas-liquid chromatographic separation of some organophosphate pesticides, their hydrolysis products, and oxons

Gas-liquid chromatographic separation of some organophosphate pesticides, their hydrolysis products, and oxons

Quantitative Determination of Fixed Acids in Wines by Gas-Liquid Chromatographic Separation of Trimethylsilylated Derivatives

Abstract A rapid and simple method was developed for gas-liquid chromatographic (GLC) separation of the trimethylsilylated (TMS) derivatives of the fixed acids present in wine. Acids were precipitated as lead salts to eliminate sugar interference. The TMS derivatives were completely separated on a 6' X 14" o.d. glass column of 3.8% SE-30 on Diatoport S (silanized support) and were measured by reacting the dried lead salts with trimethylchlorosilane and hexamethyldisilazanc in the presence of pyridine. This method permits the simultaneous determination in wine of several acids, such as succinic, malic, tartaric, and citric acids in ca 4 hours. Several other derivatives were observed in the chroniatograms but were not identified

Gas-liquid chromatographic separation of diastereoisomeric amides of racemic cyclic amines

Gas-liquid chromatographic separation of diastereoisomeric amides of racemic cyclic amines

The gas-chromatographic examination of organophosphorus pesticides and their oxidation products

A considerable number of organophosphorus pesticides have been approved for use in agriculture and increasing attention is being paid to the examination of foodstuffs and the environment for residues of those often highly toxic materials. This paper deals with the gas—liquid chromatographic separation of some organophosphorus pesticides and their metabolites using a thermionic detection system. Many of the oxidation products were prepared and optimum conditions for oxidation of the pesticides are reported.

Gas-liquid chromatographic separation of C 19 and C 21 human urinary steroids by a new procedure

Gas-liquid chromatographic separation of C 19 and C 21 human urinary steroids by a new procedure

A gas-liquid chromatographic separation and quantitative determination of some aromatic oxygenic compounds

A gas Chromatographic separation and quantitative determination of some aromatic oxygenic compounds of different chemical types and some of their isomers has been worked out. Relations between the structure of the separated substances and their Chromatographic behaviour are discussed. The results are evaluated statistically.

Gas-liquid chromatography of submicrogram amounts of drugs : II. Analysis of barbiturates and related drugs in biological media

This paper describes the gas-liquid chromatographic separation of mixtures of barbiturates in pure solution and in extracts of biological material. Using a special preparation of SE-30-tristearin on acid-washed Chromosorb W in a stainless steel column it is shown that successful resolution can be obtained with submicrogram amounts of the drugs. In some cases, 10 ng of barbiturates can be detected. Interference of other drugs and methods of eliminating this interference are described.

Gas-liquid Chromatography and Structure-Retention Time Relationship of Anhalonium Alkaloids and Related Bases

Gas-liquid chromatographic separation of 18 anhalonium alkaloids and related bases has been studied employing 1 per cent methylsiloxane polymer (containing about 5 per cent phenyl substitution) as the liquid phase. The GLC behavior of these closely related compounds suggested a structure-retention time relationship. In general, <i>N</i>-monomethylation of primary and secondary amines, <i>O</i>-methylation, or <i>C</i>-monomethylation of the bases studied was found to decrease the retention time, while introduction of hydroxyl, methoxyl, or methylenedioxy group, or an unsaturation, produced an increase in retentivity. These changes in retention time may be attributed to the changes in polarity of amino and/or phenolic hydroxyl groups brought about by substitution in or adjacent to these groups.

Gas Liquid Chromatographic Separation of Resin Acid Methyl Esters with a Polyamide Liquid Phase.

Gas Liquid Chromatographic Separation of Resin Acid Methyl Esters with a Polyamide Liquid Phase.

GAS-LIQUID CHROMATOGRAPHY OF BILE ACIDS.

AbstractMethods are reviewed for the preparation, gasliquid chromatographic (GLC) separation, identification, and quantitative estimation of the trifluoroacetyl derivatives of bile acid methyl esters. Of the stationary phases tried (SE‐30, QF‐1 and XE‐60) methylfluoroalkyl silicone (QF‐1) was best suited for analysis of the trifluoroacetates. This phase (1舑2% QF‐1 on 100舑120 mesh Gas Chrom P) allowed an orderly resolution of conformational isomers and consistently gave GLC columns (stainless steel tubes, 1/8 in. O.D. ȕ 3 ft) from which the bile acid derivatives could be recovered in high yield. Applications to biological materials are illustrated with bile acid samples from animal biles and from human duodenal drainage and feces. Identifications of the major bile acids made by the GLC of the trifluoroacetates were confirmed by results obtained with bile acid methyl esters and bile acid methyl ester acetates on QF‐1 and the other liquid phases investigated. For most mixtures of bile acids, however, it appears that GLC of methyl esters and methyl ester trifluoroacetates on QF‐1 is sufficient for a reliable recognition of common bile acids. Overall accuracy of the estimates was of the order of ŷ 5%, but it varied with the nature and concn of the component.

Analysis of hydroxy fatty acids by gas-liquid chromatography

Techniques for the gas-liquid chromatographic (GLC) separation of hydroxy fatty acids are described. Procedures are given for GLC of the methyl esters of hydroxy fatty acids from 14–18 carbons, and the acetoxy fatty acid methyl esters from 14–26 carbons. The degree of unsaturation of α-hydroxy fatty acids can be determined by GLC of acetoxy fatty esters on polyester columns. The position of the hydroxyl group on the carbon chain markedly affects retention time, as shown by GLC of hydroxymethylpalmitates with the hydroxyl group in positions 2–16. Procedures are described for the rapid preparation, characterization, and quantitation of saturated and unsaturated 2-acetoxy fatty acid methyl esters ranging from 14–26 carbons encountered in sphingolipids.

GAS-LIQUID CHROMATOGRAPHIC SEPARATION OF SULPHUR COMPOUNDS.

RESEARCH in the general area of sulphur chemistry has been increasing in the past few years at a fairly rapid rate. Hence, any new analytical methods or techniques which can simplify the isolation and/or identification of sulphur derivatives are of value. Techniques which are both qualitative and quantitative are even more desirable. Spectrophotometric and potentiometric titration techniques or a combination of these two methods of analysis have been widely used for the identification and estimation of thiols, disulphides, sulphides, sulphoxides and sulphones. Recently, Gates and Meloan1,2 have described a gas–liquid chromatographic technique for the separation and identification of a mixture of sulphoxides and a mixture of sulphones. These authors have also briefly indicated2 that separation of a sulphide–sulphoxide–sulphone mixture is feasible by their technique. This last finding has prompted us to communicate some of our results on the same problem.

Influence of Column Temperature in the Gas-Liquid Chromatographic Separation of Methyl Esters of Fatty Acids on Polyester Substrates

Operation of any polyester column at a given temperature often will not be completely satisfactory for the detection of some of the components present in complex lipid systems. Use of the same column at different temperatures to resolve components known or suspected to be present may in many cases be simpler than the use of two different columns.

Separation of Some Low Molecular Weight Fluorocarbons by Gas Chromatography.

Abstract : A gas-liquid chromatographic separation of some low molecular weight fluorocarbons is described. The separation has been effected at 0 C with a partially fluorinated acrylate as the liquid phase. As an adjunct to gas-liquid chromatography separation, separations were also carried out by gas-solid chromatography on a silica gel column under programmed temperature conditions.

Gas-Liquid Chromatographic Separation of Chlorophenols and Determination of Pentachlorophenol as Methyl Ethers

Gas-Liquid Chromatographic Separation of Chlorophenols and Determination of Pentachlorophenol as Methyl Ethers

GAS–LIQUID CHROMATOGRAPHIC ANALYSIS OF LIGNIN OXIDATION PRODUCTS

The gas–liquid chromatographic separation of vanillin, syringaldehyde, and p-hydroxybenzaldehyde has been effected using a 15% Apiezon N on Fluoropak column at 220 °C. Using standard solutions of the reference compounds and measuring peak areas, the percentage composition of mixtures of milligram amounts of these aldehydes may be determined quantitatively to within 5%.The method has been applied to the quantitative analysis of the phenolic aldehydes resulting from the alkaline nitrobenzene oxidation of aspen and spruce wood and wheat straw meals as well as the lignins isolated from these same plant materials. The results are reproducible and generally in good agreement with those reported earlier for similar lignified substances as determined using the spectrophotometer method of Stone and Blundell.

Gas-Liquid Chromatographic Separation and Determination of Methylamines

Gas-Liquid Chromatographic Separation and Determination of Methylamines

Gas-Liquid Chromatographic Separation and Analysis of Chlorinated Toluenes

Gas-Liquid Chromatographic Separation and Analysis of Chlorinated Toluenes

Selective gas-liquid chromatographic separation of aromatic compounds with tetrahalophthalate esters

Tetrahalophthalate esters were found to be selective liquid substrates for separating aromatic hydrocarbons by gas chromatography. The tetrachlorophthalates are unusually specific in separating meta- and para-isomers, including the xylenes; this makes possible the gas chromatographic analysis of mixtures of these isomers. “Charge transfer” interaction between the volatile aromatic compounds (donors) and the tetrahalophthalates (acceptors) is apparently responsible for selectivity. Variations in the elution order of alkylaromatics may be interpreted qualitatively in terms of structure or molecular composition. Gas chromatography, in turn, provides a measure of the complexing or degree of interaction of aromatic compounds with the tetrahalophthalate esters as well as information on salient stereochemical features that effect interaction.