Gas-liquid Chromatographic Data Research Articles

A computer search system for the identification of drugs using a combination of thin-layer chromatographic, gas-liquid chromatographic and ultraviolet spectroscopic data.

A computer-based retrieval system has been developed for the identification of drugs and poisons in forensic toxicology using thin-layer chromatographic, gas-liquid chromatographic and ultraviolet spectroscopic data. The data collection has been compiled from various published and unpublished sources and contains information for over 1600 compounds. The retrieval program uses the concept of discrepancy index to match experimental data for an unknown with the information in the data file. Additional features include a series of help routines for new users and the facility to retrieve information on specific compounds or groups of compounds in the data collection.

The Identification of Methoxy-N-Methylamphetamines

Abstract Thirteen mono, di, and trimethoxy-N-methylamphetamines have been synthesized and characterized. Gas liquid chromatographic data and ultraviolet, infrared, proton magnetic resonance, and mass spectra are presented. The specificity of each technique for the identification of methoxy-N-methylamphetamines is discussed.

Analysis of molluscan sterols: Colorimetric methods.

The wide variety of sterols normally found in extracts of bivalve molluscs leads to high variability in analytical data obtained with colorimetric (chole)sterol methods. Total sterol levels in oyster (Crassostrea virginica) extracts were determined using the Liebermann-Burchard reagent, an acid-FeCl3 reagent and a cholesterol oxidase procedure. The data from the latter two agreed to within 5.4% and yielded about 30% higher estimates of sterol content than the Liebermann-Burchard test. Gas-liquid chromatographic data also are compared.Several pure sterols, selected because of their presence in oyster sterol fractions or because of their structural similarities to such sterols, were examined using each of the three procedures. Sterols, differing from cholesterol only with regard to the side chain, reacted 80-102% as well as cholesterol with the acid-FeCl3 reagent and cholesterol oxidase. The Liebermann-Burchard reaction was more specific for cholesterol. The colorimetric cholesterol oxidase method is recommended for the estimation of total molluscan sterol content.

Estimation of chain branching in paraffin waxes using proton magnetic resonance spectroscopy and gas—liquid chromatography

Two methods using high-resolution proton magnetic resonance spectroscopy (PMR) in conjuction with gas—liquid chromatography (GLC) are described which give a rapid and reliable estimation of the extent of chain branching in paraffin-wax mixtures. Our initial approach has been to compare the area of the methyl resonances of the PMR signal to that of the methylene plus methine protons, having previously calculated an average molecular weight from GLC data. The second method makes use of the slight upfield shift and characteristic splitting of methyl protons attached to methine groups. The contribution of these shifted resonances to the area derived from all the methyl protons is used to estimate directly the degree of branching. The limitations of the techniques and the sources of error are discussed. However, the good numerical agreement between the two methods prompts us to support the postulate that branching in natural paraffin waxes consists to a very large extent of methyl branches only.

Radioimmunoassay of methaqualone in human urine compared with chromatographic methods.

The 125I-radioimmunoassay for methaqualone in human urine was evaluated by a comparison with newly modified gas-liquid chromatographic and thin-layer chromatographic methods. The statistically significant sensitivity value for the radioimmunoassay was at 2 microgram of methaqualone per liter of urine. The coefficient of variation was 2.88 +/- 0.39% interassay and 2.71 +/- 0.16% intraassay. There was cross-reactivity only with metabolites of methaqualone, 4'-hydroxymethaqualone being twice as sensitively measured as methaqualone. There was complete agreement between results by radioimmunoassay and by gas-liquid chromatography in 96.7% of the samples analyzed. Only 1.2% of the radioimmunoassay values were false positives, and 2.1% false negatives (phi = 0.8917, P less than 0.001). Comparisons between the thin-layer chromatographic data and the gas-liquid chromatographic or radioimmunoassay data showed less agreement because of the 50- to 200-fold higher sensitivity of the latter two techniques. Gas-liquid chromatography therefore appears to represent the best reference method for the evaluation of the radioimmunoassay, which appears to be a very sensitive and reliable technique for detecting methaqualone and its metabolites in human urine.

Spectroscopic and Chromatographic Identification of Precursors, Intermediates, and Impurities of 3,4-Methylenedioxyamphetamine Synthesis

Abstract The ultraviolet, infrared, nuclear magnetic resonance, and mass spectra of a number of precursors, intermediates, and impurities of 3,4-methylenedioxyamphetamine (MDA) synthesis are presented as well as gas-liquid and thin layer chromatographic data. Test results are given on the precursors safrole, isosafrole, and piperonal; the intermediates isosafrole glycol, N-formyl-MDA, and l-(3,4-methylenedioxyphenyl)- 2-nitro-l-propene; the impurities di[l- (3,4-methylenedioxyphenyl) -2-propyl] amine, di[l - (3,4 - methylenedioxyphenyl) -2- propyl] methylamine, and 3,4-methylenedioxyphenyIpropane; and the product MDA. The data are discussed and 2 methods of MDA synthesis are summarized, in which the precursors, intermediates, and impurities are encountered.

Separation of alkadien-1-ol acetate geometric isomers by capillary gas-liquid chromatography

Gas-liquid chromatographic data have been presented for the analyses of alkadien-1-ol acetates; these compounds have importance in the field of insect sex attractants. The use of a support-coated open tubular column prepared with diethylene glycol succinate liquid phase for these analyses has been of great utility in monitoring geometric purity. The geometric purity of such compounds must be determined to assure accurate evaluation as insect sex attractants since contamination with small amounts of another isomer may result in complete inactivation.

Gas-liquid chromatographic studies of reactions and structural relationships of steroids : V. concurrent substitution in the pregnane side-chain and position 11

Qualitative and quantitative effects of classical reactions on steroids observed by gas-liquid chromatography (GLC) under standardized conditions, including the double internal standard technique, are reported. Simple procedures applicable to nanogram amounts of reactants are described. Reactions studied include the conversion of keto groups to hydroxyl groups by NaBH 4, and the removal of the pregnane side-chain with NaBiO 3. GLC chromatograms readily provide information on effects on functional groups at positions 3, 11, 17, 20, and 21 and the retention times of many steroids unavailable from commercial sources. GLC data analysis provides relationships between steroid structure and retention time from which methods for the computation of retention times and steroid identification are designed. The accuracy of these methods is demonstrated.

Gas-liquid chromatographic studies of reactions and structural relationships of steroids: IV. Substitution in the pregnane side-chain

Qualitative and quantitative effects of classical reactions on steroids observed by gas-liquid chromatography (GLC) under standardized conditions, including the double internal standard technique are reported. Simple procedures applicable to nanogram amounts of reactants are described. Reactions studied include the conversion of keto groups to hydroxyl groups by NaBH 4, and to dioxolone derivatives by 1,2-diethanol; 17α-hydroxylation of C20-ketosteroids; the conversion of hydroxyl groups to trimethylsilyl (TMS) ethers by hexamethyldisilazane; the hydrolysis of dioxolone and TMS derivatives by H +. Effects of the Wolff-Kishner reagents, and CrO 3 were also studied. GLC chromatograms of reaction mixtures of single- and multistep reactions readily provide information on effects on functional groups at positions 3, 17, 20, and 21 in the pregnane series, and the retention times of many steroids unavailable from commercial and other sources. GLC data analysis provides relationships between steroid structure and retention time from which methods for the computation of retention times and for steroid identification are designed. The accuracy of the computation methods is demonstrated.

Effect of electronic cooking on fatty acids in meats

This study was conducted to investigate the effects of microwave energy and conventional heating on the fatty acid composition of meats and poultry. Data on weight loss and cooking time with both heat treatments are reported. Gas-liquid chromatographic data of the methyl esters of myristic, palmitic, stearic, oleic, linoleic, and linolenic acids revealed no significant difference between fatty acid composition as a result of heat treatment. Decreases in fatty acids appeared to be mainly due to a change in oleic acid. Poultry appeared to be the species most affected by heat treatment. Cooking times were much shorter for the electronic method and varied among species. No significant difference was found in weight loss as a result of treatment of beef or pork. Poultry weight losses were greater for the conventional method.

Solution and complexing studies. II. Comparison and correlation of nuclear magnetic resonance and gas-liquid chromatographic data

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolution and complexing studies. II. Comparison and correlation of nuclear magnetic resonance and gas-liquid chromatographic dataJ. H. Purnell and J. M. Vargas de AndradeCite this: J. Am. Chem. Soc. 1975, 97, 13, 3590–3593Publication Date (Print):June 1, 1975Publication History Published online1 May 2002Published inissue 1 June 1975https://doi.org/10.1021/ja00846a005RIGHTS & PERMISSIONSArticle Views30Altmetric-Citations30LEARN 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 (431 KB) Get e-Alerts Get e-Alerts

The use of butaneboronic esters in the gas-liquid chromatography of some carbohydrates

Gas-liquid chromatographic data for the butaneboronic esters and trimethyl-silyl derivatives of some monosaccharides and alditols are described. Mass-spectral data for the trimethylsilylated butaneboronates of D-fructose, D-glucose, D-galactose, and D-mannose are also recorded. The butaneboronic esters are useful for the qualitative identification of some monosaccharides, and are of particular value in the quantitative analysis of mixtures of D-glucose and D-fructose. The low rate of trimethylsilylation of D-fructose is examined.

Gas—liquid chromatographic studies of reactions and structural relationships of steroids : Part III. 11α-hydroxysteroids of the androstane and pregnane series

Qualitative and quantitative effects of classical reactions on steroids observed by gas—liquid chromatography (GLC) under standardized conditions, including the double internal-standard technique, are reported. Simple procedures applicable to nanogram amounts of reactants which afford excellent yields of the major products are described. Reactions studied include the Wolff—Kishner removal of keto groups, their conversion into hydroxyl groups with sodium—ethanol or sodium borohydride and into dioxolone derivatives with ethylene glycol; the conversion of hydroxyl into keto groups with chromium trioxide and to trimethylsilyl (TMS) ethers by hexamethyldisilazane; the hydrolysis of dioxolone and TMS derivatives by H +. Gas—liquid chromatograms of reaction mixtures of single- and multistep reactions readily provide information on the effects on the 11α-hydroxy and other functional groups at positions 3 and 17 (androstane series) and positions 3 and 20 (pregnane series), and the retention times of many steroids unavailable from commercial or other sources. GLC data analysis provides relationships between steroid structure and retention time from which methods for the computation of retention times and for steroid identification are designed. The accuracy of the calculation methods is demonstrated.

Gas-liquid chromatographic studies of reactions and structural relationships of steroids : II. Positions 3, 11, and 20 in the pregnane series

Qualitative and quantitative effects of classical reactions on steroids observed by gas-liquid chromatography (GLC) under standardized conditions, including the double internal standard technique, are reported. Simple procedures applicable t nanogram amounts of reactants which afford excellent yields of the major products are described. Reactions studied include the Wolff-Kishner removal of keto groups (WK), their conversion to hydroxyl groups by NaBH 4 (RD), and to dioxolone derivatives by ethylene glycol (DO); the conversion of hydroxyl to keto groups by CrO 3 (OX), and to TMS ethers by hexamethyldisilazane; the hydrolysis of dioxolone and TMS derivatives by H + (HY). GLC chromatograms of reaction mixtures of single and multistep reactions readily provide information on effects on functional groups at positions 3, 11, and 20 in the pregnane series, and the retention times of many steroids unavailable from commercial or other sources. GLC data analysis provides relationships between steroid structure and retention time from which methods for the computation of retention times and for steroid identification are designed. The accuracy of the computation methods is demonstrated.

Gas-liquid chromatographic studies of reactions and structural relationships of steroids : Part I. Positions 3, 11 and 17 in the androstane series

Qualitative and quantitative effects of classical reactions on steroids observed by gas-liquid chromatography (GLC) under standardized conditions, including the double internal standard techique, are reported. Simple procedures, applicable to nanogram amounts of reactants, that afford excellent yields of the major products are described. Reactions studied include the Wolff-Kishner removal of keto groups (WK), their conversion into hydroxyl groups with sodium borohydride and into dioxolone derivatives with ethylene glycol: the conversion of hydroxyl into keto groups with chromium trioxide and into trimethylsilyl (TMS) ethers with hexamethyldisilazane: and the hydrolysis of dioxolone and TMS derivatives with H +. Gas-liquid chromatograms of reaction mixtures of singe- and multi-step reactions readily provide information on the effects on functional groups at positions 3, 11 and 17 in the androstane series and the retention times of many steroids unavailable from commercial or other sources. GLC data analysis provides relationships between steroid structure and retention times, from which methods for the calculation of retention times and for steroid identification are designed. The accuracy of the calculation methods is demonstrated and conditions for their efficient application are discussed.

Automatic normalization of gas chromatographic data with a desk-top computer

A procedure is presented for the automatic normalization of gas-liquid chromatographic data using a small desk-top computer. The data must be in digital format such as that produced by an electronic digital integrator with a punch-tape output. Data is transferred from the paper tape to the computer by means of a Teletype unit equipped with a tape-reader, and a solenoid deck to actuate the computer keys. The computer employed is the Olivetti-Underwood Programma 101 and the solenoid deck and interfacing is marketed by Nuclear-Chicago Corp. for processing data from a liquid scintillation counter. The program for the computer permits automatic calculation of relative retention data and normalization of the peak areas with a minimum of operator intervention.

Synthesis of C7-C9 2,2- and 3,3-dimethylalkanes from C6-C8 saturated alcohols of normal structure

1. C7-C9 2,2- and 3,3-dimethylalkanes were synthesized from saturated C6-C8 alcohols of normal structure using carbonylation, reduction of the acid chlorides, and the Kishner reaction. 2. From gas-liquid Chromatographic data the composition of the C7, C8, and C9 carboxylic acid methyl esters completely corresponds to the composition of the mixture of 2,2- and 3,3-dimethylalkanes obtained from them.

Computer treatment of gas-liquid chromatographic data, with special reference to fatty acid methyl esters

A computer program is described which analyzes output punched directly onto paper tape from a gas-liquid chromatograph. Although this program was written specifically for samples of fatty acid methyl esters derived from adipose tissue triglycerides which are eluted within 1 hr, modification of the dimension statements in the program would enable it to deal with samples which require a longer time to come off the column. The salient features of the rationale of the program are discussed in detail, particularly the procedures for base line correction and for estimating the contributions from components which are not perfectly separated in the column. Examples are given of the program in practice, of comparing the results it gives with those obtained by manual triangulation of the areas on a recorder chart, and of indicating the range of column load over which we have found that it operates satisfactorily. A sample computer print-out from the program is presented and interpreted.

CORRELATION BETWEEN GAS‐CHROMATOGRAPHIC PATTERNS AND FLAVOR EVALUATION OF CHEMICAL MIXTURES AND OF COLA BEVERAGES

SUMMARYTwo methods of discriminant analysis, Chi‐square tests, “t” tests and analysis of variance were applied to gas‐liquid chromatographic (GLC) data to compare GLC measurements of food volatiles with organoleptic evaluation of flavor. Model systems composed of ethyl butyrate, ethyl heptylate and benzaldehyde were used for one set of trials. A second system consisted of blends of Pepsi‐Cola® and Coca‐Cola®. The stepwise discriminant analysis (SDA) procedure described by Powers et al. (1968) was only moderately successful in classifying the mixtures when applied to the GLC data for the model systems, but the cola blends could be classified readily. From GLC data, cola blends differing from each other by only 7–10% could be distinguished. A new discriminant analysis program, designated MUDAID by its originator (Bargmann, 1967), is more useful for predictive purposes. The analysis yields the correlation coefficients for each peak area with sample differences and the weighting factors. Discriminant equations can thus be written. By substitution of measurement values for unknowns, their identity may be predicted. Organoleptic subthreshold additive effects could not be demonstrated with binary mixtures of flavor substances, but judge‐compound interaction effects were observed.

The interference of free and esterified cholesterol in the spectrofluorimetric measurement of plasma 11-hydroxysteroids.

SUMMARY Cholesterol and cholesterol esters have been identified on the basis of thin-layer and gas—liquid chromatographic data and fluorimetric characteristics as major interfering fluorogens in a simple fluorimetric method for determining plasma corticosteroids. In a small series of normal subjects the average concentration of fluorogen, which was not 11-hydroxysteroid, was 3·4 μg. apparent cortisol/100 ml. plasma, equivalent to 22·4% of the total fluorogen present.