Gas-liquid Chromatographic Method For Determination Research Articles

Simplified determination of serum cholesterol sulfate by gas-liquid chromatography combined with cyclohexylsilane-bonded phase column purification

A new gas-liquid chromatographic (GLC) determination of cholesterol sulfate (CS) and dehydroepiandrosterone sulfate (DHEAS) for a biochemical diagnosis of recessive X-linked ichthyosis (RXLI) is described. Although the GLC method for determination of CS is known to be more sensitive than the thin layer chromatographic (TLC) method, the former method has not been widely employed because of its complicated pre-purification steps. The present method allows us to measure the serum levels of CS and DHEAS without tedious purification steps such as multiple conventional column chromatography and preoperative thin layer chromatography. Sulfated steroids are rapidly purified with a commercially available mini disposable cyclohexylsilane-bonded phase (CH) column, CH BOND ELUT, and the purified steroids after desulfation are converted to water-resistant tert-butyldimethylsilyl ether derivative for the GLC analysis on dual 2m glass columns packed with 2% XE-60 on Chromosorb W. By the present method, serum CS concentrations in RXLI patients were shown to be about 10 times higher than those in patients with ichthyosis vulgaris, carriers of RXLI, and healthy subjects. This method is more suitable not only for a biochemical diagnosis of RXLI but also for studies on the metabolism of sulfated steroids than the previous time-consuming GLC methods.

A gas-liquid chromatographic method for steric analysis of epoxy acids

A gas-liquid chromatographic method for determination of the absolute configuration of the two chiral carbon atoms of epoxy fatty acids was developed. The method involved (1) conversion of the saturated epoxy ester into a pair of regioisomeric allylic alcohols by consecutive treatments with selenophenoxide anion and hydrogen peroxide, (2) oxidative ozonolysis performed on the (−)-menthoxycarbonyl derivatives of the allylic alcohols, and (3) steric analysis of the resulting two 2-hydroxy acids (methyl esters, (−)-menthoxycarbonyl derivatives) by gas-liquid chromatography using appropriate reference compounds. Application of the method for steric analysis of several synthetic epoxyoctadecanoates as well as (+)-vernolic acid derived from Vernonia galamensis is described.

Gas-liquid chromatographic method for determination of partial molar free energy at infinite dilution in volatile solvent and its application to acetonitrile/benzene systems

Gas-liquid chromatographic method for determination of partial molar free energy at infinite dilution in volatile solvent and its application to acetonitrile/benzene systems

Rapid Gas-Liquid Chromatographic Method for Determination of Sulfathiazole in Swine Feed

A gas-liquid chromatographic (GLC) method for determining residues of sulfathiazole (STZ) in swine feed has been developed. Feed is extracted first with acetone and then with ammonia-acetone. STZ is isolated from other feed extractives on a Sephadex LH-20 column with methanol-toluene. The sulfa residues are methylated with diazomethane, and the eluate is evaporated to dryness. A solution containing an internal standard of methyl sulfasymazine is used to dilute the sample before injection onto an OV-25 GLC column. The precision of the method was determined by assaying 10 sets of feed spiked at 0.5, 1, 2, and 5 ppm STZ. The mean recoveries and coefficients of variation were 90.2 (5.90), 89.5 (4.67), 87.4 (5.62), and 87.7% (4.29), respectively. The critical steps of the method, including the stability of STZ, were also determined.

Modified Gas-Liquid Chromatographic Method for Determination of Compound 1080 (Sodium Fluoroacetate)

A method capable of determining 0.1 ppm 1080 (sodium fluoroacetate) in 1 g animal tissue was developed. It involves extraction of 1080 from the sample with acetone-water, and then evaporation of the acetone followed by extraction of 1080 as fluoroacetic acid from water with ethyl acetate. Ethyl acetate is removed by volatilization from fluoroacetic acid which is retained as the triethanolammonium fluoroacetate salt. Fluoroacetic acid is subsequently derivatized with alpha-bromo-2,3,4,5,6-pentafluorotoluene and quantitated by gas-liquid chromatography with an electron capture detector. The method is rapid and requires no special apparatus or equipment and no more than 12 mL of any one solvent. Recoveries of 1080 from tissue samples fortified with 0.1-100 ppm averaged about 85%.

Rapid Gas-Liquid Chromatographic Method for Determination of Sulfamethazine in Swine Feed

A gas-liquid chromatographic method is described for the quantitative determination of trace amounts of sulfamethazine in swine feed. Sulfamethazine is extracted in ammoniated acetone and isolated from other extractants on a Sephadex LH-20 column. The eluate is methylated with diazomethane and evaporated to dryness. The residue is dissolved in a solvent containing an internal standard of methyl sulfasymazine before being injected onto an OV-25 GLC column. An estimation of precision was established by assaying 10 sets of swine feed fortified with 0.5, 1,2, and 5 ppm SMZ. Mean recoveries were 96.0, 94.3, 93.5, and 94.0%, respectively, with an average coefficient of variation of 3.07%. The critical steps and ruggedness of the method were also determined.

A capillary gas-liquid chromatographic method for determination of ethylenethiourea and prophylenethiourea in hops, beer, and grapes.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA capillary gas-liquid chromatographic method for determination of ethylenethiourea and propylenethiourea in hops, beer and grapesSiegfried Nitz, Prannath Moza, and Friedhelm KorteCite this: J. Agric. Food Chem. 1982, 30, 3, 593–596Publication Date (Print):May 1, 1982Publication History Published online1 May 2002Published inissue 1 May 1982https://doi.org/10.1021/jf00111a044RIGHTS & PERMISSIONSArticle Views118Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (454 KB) Get e-Alerts Get e-Alerts

A Simple, Direct Extraction Method for Gas-Liquid Chromatographic Determination of Valproic Acid in Plasma

A Simple, Direct Extraction Method for Gas-Liquid Chromatographic Determination of Valproic Acid in Plasma

Improved Method for Gas-Liquid Chromatographic Determination of Clopidol in Chicken Tissues

A sensitive and specific gas-liquid chromatographic (GLC) method has been developed for determining low levels of clopidol in chicken tissues. Clopidol is extracted from the tissues with methanol, and cleaned up on an alumina column and an anion exchange resin column with 0.1% acetic acid--methanol as eluate. Clopidol is methylated with diazomethane, and then determined by GLC. 2,4-Dinitro-1-chlorobenzene is used as an internal standard. The method is applicable to levels as low as 2 ppb in chicken tissues. Recoveries of 2--20 ppb clopidol added to tissues averaged 87% for muscle, 84% for liver, 80% for kidney, and 76% for fat.

Gas-liquid chromatographic method for determination of ginsenosides in Panax ginseng

The most important saponins contained in Panax ginseng were determined by gas-liquid chromatography after trimethylsilylation. Results are reported for the analysis of ginseng roots, leaves and flowers of different origin.

Correlation of the “EMIT” with a Gas-Liquid Chromatographic Method for Determination of Antiepileptic Drugs in Plasma

We report a study of the comparison of antiepileptic drugs (phenobarbital, phenytoin, primidone, and carbamazepine) by the Enzyme Multiplied Immunoassay Technique "EMIT" and the gas chromatography (GLC) method. Overall, reasonable correlations were observed for all of the above-mentioned assays by both methods in the majority of samples included in this study. Our observations for statistical and clinical differences at various levels of phenobarbital and phenytoin are discussed. A suggestion is provided in order to avoid a major discrepancy (approximately 30% higher values by EMIT vs GLC) in results observed from the "Bottom of the Bottle Effect" for EMIT reagent.

Rapid, sensitive gas-liquid chromatographic method for determination of amitriptyline and nortriptyline in plasma using a nitrogen-sensitive detector

A simple gas chromatographic method for determination of amitriptyline and nortriptyline in plasma using a nitrogen-sensitive detector is described. Concentrations of both drugs as low as 10 ng per ml plasma were measured. The precision and accuracy of the method are within acceptable limits.

Sensitive gas-liquid chromatographic method for determination of valproic acid in biological fluids

Sensitive gas-liquid chromatographic method for determination of valproic acid in biological fluids

Studies on Environmental Contamination by Polychlorinated Naphthalenes (PCN). II. Determination of PCN in Biological Samples by Gas-Liquid Chromatography

A method for gas-liquid chromatographic determination of polychlorinated naphthalenes (PCN) in biological samples were investigated. This method is based on saponification of the sample with an alkaline ethanolic solution, extraction of PCN with hexane, treatment of the extract with concentrated sulfuric acid, clean-up of the extract by silica gel column chromatography, the separation from polychlorinated biphenyls by thin-layer chromatography on polyamide, and then the determination by gas-liquid chromatography using an electron-capture detector. Fatty biological samples fortified with PCN at a level of 10 ppb were analyzed by this method, with recoveries of 83.6-89.3%.

Collaborative Study of the Gas-Liquid Chromatographic Method for Determination of Stereochemical Composition of Amphetamine

Abstract Eight laboratories collaboratively studied a method for the quantitative GLC determination of d- and l-amphetamine in tablets. The drugs are separated from tablet excipients by column chromatography and reacted with Ntrifluoroacetyl-( 0-prolyl chloride, and the resulting derivatives are analyzed by GLC. The samples consisted of commercial d-amphetamine sulfate tablets (with and without butabarbital), dl-amphetamine sulfate tablets, and a mixed d- and l-amphetamine sulfate standard. Recoveries were acceptable, and the standard deviations never exceeded 0.64%. The results demonstrate that the method gives good precision and accuracy, and the method is recommended for adoption as official first action.

Gas-Liquid Chromatographic Method for Determination of Trichlorfon in Plant and Animal Tissues

Gas-Liquid Chromatographic Method for Determination of Trichlorfon in Plant and Animal Tissues

Gas-Liquid Chromatographic Method for Determination of Fat-Soluble Vitamins. III. Evaluation of a Vacuum Distillation Procedure for Vitamin E Isolation, Using C-14 Labelled Alpha-Tocopheryl Acetate

Abstract Alpha-tocopheryl acetate, carbon-14 labelled in the methyl group at the two position, was used to determine the stability and recovery of the vitamin during vacuum distillation (140–160°C, and 0.020 mm Hg pressure, 60 minutes). Evaluation was based on measurements of radioactivity with a liquid scintillation spectrometer and a lowbackground Geiger counter. Recoveries of 20 mg of the pure compound were nearly quantitative (97%). Recoveries of the tocopheryl ester added to lard, “stripped” of vitamin E, at 0.5 mg/g or less and to butter at 0.1 mg/g were 98 and 82%, respectively. Results of the differential counting technique suggest that the ester is increasingly unstable at temperatures exceeding 160° and that a molecular rearrangement probably takes place.