The analysis of 1,2-epoxyalkanes by gas liquid chromatography

Terminal epoxides react quantitatively with methanol in the presence of boron trifluoride to give both primary and secondary hydroxy methyl ethers. These derivatives are useful in the analysis of terminal epoxide mixtures by gas liquid chromatography. This procedure is compared with the conventional method and with a procedure in which the 1,2-epoxyalkanes are reduced to the corresponding secondary alcohols with LiAlH₄. A statistical analysis of experimental data obtained from known mixtures of long chain epoxides is described. Results of this analysis demonstrate the improved accuracy and precision of the method as compared to the other methods investigated. LiAlH₄ reduction is the preferred method of analysis for the more reactive epoxides as well as for the cyclic epoxides. This procedure is particularly useful in the analysis of epoxides containing a tertiary carbon atom. The application of this technique to other epoxides is expected to improve their analysis, but further work is necessary. Presented at the AOCS Meeting, Minneapolis, October 1969.     

2,4-二硝基苯肼显色法测定环己酮含量

为简化定向进化筛选环己酮还原能力提高的突变型糖多孢红霉菌聚酮合成酶酮还原酶域的繁琐工作,建立了利用环己酮和2,4-二硝基苯肼的显色反应来检测环己酮含量的方法。环己酮浓度在0～5mg·mL-1范围内与吸光度线性关系良好,线性相关系数为0.9973。在10mL转化液的实验条件下,方法的检测限为188μg.L-1,相对标准差为1.52%。该方法操作简便、灵敏度较高、结果可靠,能满足筛选突变体的要求。     

Rapid ethanolysis procedure for jojoba wax analysis by gas liquid chromatography

A rapid ethanolysis procedure for preparing jojoba wax for gas liquid chromatographic analysis is described. The wax esters are hydrolyzed by refluxing 4 drops of jojoba wax in 5% HCl in anhydrous ethanol in a test tube. The resulting fatty acid ethyl esters and fatty alcohols are separated and quantitated by a single gas liquid chromatographic run. Analysis of duplicate samples by this procedure gives essentially the same results as a procedure which requires 10 times more sample and reagents and considerably more time.     

Jojoba oil analysis by high pressure liquid chromatography and gas chromatography/mass spectrometry

Two analytical procedures for determining com-positions of jojoba liquid wax esters are described and compared. One, the more tedious, involves separation of wax ester homologs by high pressure liquid chro-matography followed by determination of the acid and alcohol moieties from each homolog. The second allows rapid determination of wax ester composition by gas Chromatographic separation of hydrogenated jojoba wax esters according to chain length, followed immediately by ancillary mass spectrometric identifi-cation of the acid and alcohol moieties. Double bonds in the alkyl chains in jojoba liquid waxes were almost exclusively (98%) ω-9, when examined by gas chro-matography/mass spectrometry (GC/MS) and ozonolysis/GC/MS. Presented in part at the 2nd International Conference on Jojoba and Its Uses, Ensenada, Mexico, February, 1976.     

The analysis of glycerol by gas chromatography

Commencai glycerol and its organic impurities can be measured accurately by a single gas Chromatographic GC analysis utilizing Tenax-GC® and flame detection.     

Sources of error in the analysis of glucosinolates by gas liquid chromatography

A study was made of the accuracy and precision of glucosinolate determination by gas liquid chromatography (GLC) after transformation of the glucosinolates to desulfoglucosinolates and silylation. The condition of the GLC column and the cleanness of the injection port were found to be crucial for quantitative determination of the glucosinolate silyl ethers. The relative stabilities of glucosinolate silyl ethers in pyridine solution remained constant over a period of weeks in air at ambient temperature.     

Analysis of whole beeswax by gas liquid chromatography

Gas liquid chromatographic analysis of unfractionated beeswax (treated with diazomethane) using Dexsil 300 as liquid phase gives a good separation of hydrocarbons, free fatty acids as methyl esters, and long chain monoesters. These components can be estimated using internal standards and together account for ca. 65% of the wax. Petroleum hydrocarbon or fatty acid adulterants can be detected. Unsaturated hydrocarbons are partially resolved from the corresponding saturated compounds. Issued as NRCC No. 12775.     

Determination of plasma tocopherols by gas liquid chromatography

A method is described for the separation and determination of plasma tocopherols by gas liquid chromatography (GLC). Proteins in 0.1 g samples of plasma were precipitated with ethanol containing a known amount of 5,7-dimethyltocol which served as an internal standard. Tocopherols were extracted into petroleum ether, purified by thin layer chromatography and analyzed as trimethylsilyl ethers by gas liquid chromatography (GLC) on 0.5% Apiezon L. Recoveries of α- and γ-tocopherols averaged 100% and 93%, respectively. The mean total tocopherol content of eight human plasma samples was 8.5 μg/g by GLC and 9.9 μg/g by a ferric chloride-α,α′-dipyridyl method. The α- and γ-tocopherol contents of 16 human plasma samples ranged from 4.0 to 12.3 μg/g and 0.6 to 2.1 μg/g, respectively.     

气相色谱法测定氯乙酸母液

通过对氯乙酸母液生成氯乙酸乙酯的酯化条件和色谱分析条件的研究,确定了以浓 硫酸为催化剂,以三氯甲烷为萃取剂的酯化条件,并采用热导检测器,面积归一化法进行定量。     

Comparison of some commercial waxes by gas liquid chromatography

Volatile components (hydrocarbons, monoesters, free acids as methyl esters and free alcohols as acetates) of seven unhydrolyzed commercial waxes-ouricury, carnauba, Chinese insect, lac, esparto, candelilla and Japan wax—have been analyzed and compared by gas liquid chromatography. Though appreciable portions of the waxes were nonvolatile, the results were sufficient to distinguish the seven waxes completely. Methanolysis products were analyzed directly by gas liquid chromatography, and the results agreed with those previously obtained for hydrolysis products of these waxes. Ouricury wax gave 18% C₂₄−C₃₄ αω-diols and 4% C₂₄−C₃₂ ω-hydroxy acids, in addition to 28% C₂₀−C₃₂ aciods and 17% C₂₂−C₃₄ alcohols, on methanolysis. NRCC No. 13387.     

Stereospecific analysis of triacyl-sn-glycerolsvia resolution of diastereomeric diacylglycerol derivatives by high-performance liquid chromatography on silica

The compositions of positionssn-1, 2 and 3 of triacylglycerols can be determined by partial hydrolysis with ethyl magnesium bromide, derivatization of the total products with (S)-(+)-1-(1-naphthyl)ethyl isocyanate and isolation of the diacyl-sn-glycerol urethane derivatives by chromatography on solid-phase extraction columns containing an octadecylsilyl phase. The diastereomericsn-1,2-and 2,3-diacylglycerol derivatives are separated by high-performance liquid chromatography on silica for determination of their fatty acids by gas chromatography. Each step in the process has been evaluated rigorously. The compositions of all three positions can be calculated with good accuracy from the analyses of these compounds and that of the total triacylglycerols. Although the 1,3-sn-diacylglycerol derivatives can also be isolated easily, they do not give reliable results for the composition of positionsn-2 because acyl migration occurs during their generation. The stereospecific analysis procedure has been applied to some plant and animal triacyl-sn-glycerols of commercial and scientific interest, containing predominantly C₁₆ and C₁₈ fatty acids,i.e. safflower, sunflower, olive and palm oils, tallow, egg and rat adipose tissue. The method is not at present suited to the analysis of more complex triacylglycerols, such as milk fat or fish oils, and problems associated with these are discussed.     

Quantitative analysis of short chain fatty acids using gas liquid chromatography

The short-chain fatty acids, propionic to pelargonic, have been analyzed by gas liquid chromatography, as their butyl, phenacyl, and decyl esters to overcome losses due to their volatility. The three methods are compared and the decyl ester procedure offers the most advantages. Presented in part at the AOCS meeting in Los Angeles, Calif., 1959. Issued as N.R.C. No. 7261. National Research Council of Canada Postdoctorate Fellow 1957–1959.     

液液小体积萃取-气相色谱质谱法测定地表水中2,4-二硝基甲苯和2,4-二硝基氯苯

本文建立了一种液液小体积萃取结合气相色谱质谱法测定地表水中2,4-二硝基甲苯和2,4-二硝基氯苯的方法.实验结果表明,2,4-二硝基甲苯和2,4-二硝基氯苯在10.0～ 160μg·L-1浓度范围内线性关系良好,加标回收均在92.8％～ 103.5％之间,精密度测试结果范围在1.43％～4.05％之间,符合分析测试的要...     

Fatty acid composition of capsicum oils by gas liquid chromatography

The fatty acid composition of oils extracted from various parts (pericarp, seeds and stem) of the fruit ofCapsicum and from samples of Greek red pepper itself were obtained by gas liquid chromatography. Samples from three different varieties ofCapsicum annuum, cultivated in the region of Almopia, Greece, were taken from two crops (1967, 1968) and examined. The results are discussed. No characteristic differences in fatty acid composition of the corresponding samples of the parts ofCapsicum fruit of the three Greek varieties were noticed and there was no difference between the two crops. However, considerable differences in fatty acid composition between Greek and American varieties were observed, probably due to climatic conditions. Presented at the Association of Greek Chemists Meeting, Athens, 1970.     

The analysis of alkyl aryl sulfonates by micro desulfonation and gas chromatography

The structural analysis of micro quantities of alkyl aryl sulfonates by presently known chemical and spectroscopic techniques has been an exceedingly difficult task. The formidable nature of such analyses is due largely to the essential nonvolatility of the sulfonates, a fact which precludes the application of gas-liquid chromatography and mass spectrometric techniques. The present paper describes an approach wherein gas chromatography is made applicable to analysis of micro quantities of sulfonates. The key to the approach is a microchemical desulfonation procedure. This process yields the parent hydrocarbon, which is volatile and hence amenable to analysis by gas-liquid chromatography and mass spectrometry. Presented in part at the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, 1960.     

用毛细管气相色谱仪分析DMC组成的方法

建立了采用毛细管气相色谱仪分析甲基环硅氧烷混合物(DMC)组成的方法。通过改变柱子类型、升温程序等，得到了测定DMC的最佳气相色谱分析条件，获得了良好的分析结果。该法具有快速、准确、精密度高的优点。     

气相色谱法同时测定敌百虫和毒死蜱的含量

使用1m×3mm(id)的玻璃柱,内填3%OV 17/ChromosorbWAW DMCS,以4,4'二异丙基联苯为内标物,采用FID检测器和柱程序升温,对试样中的敌百虫和毒死蜱进行分离和定量测定。方法的线性相关系数为0.9997,敌百虫的相对标准偏差为0.45%,毒死蜱为0.69%,敌百虫的回收率为99.5～100.1%,毒死蜱为99.6～100.2%。本法适用于4.5%混配剂中敌百虫和毒死蜱含量的测定。     

Quantitative analysis of copolyamides and copolyesters by gas chromatography

Procedures were developed for the analysis of copolyesters and copolyamides by saponification or hydrolysis of the copolymers to their component dicarboxylic acids, glycols, amino acids, or diamines and quantitatively identifying these by gas chromatography. The alcohols, amines and acids were converted to volatile trimethylsilyl derivatives for the analysis, and linear correlations were observed between carbon atom contents of these derivatives and retention times in the chromatograph.