High-resolution gas chromatographic determination of alkanols in oils extracted from olives

Polar columns with stationary phases characterized by high thermal stability have attracted a great deal of interest in the study of lipid compounds that have, until recently, been studied with nonpolar columns. Such polar columns have also proved useful in the study of the entire unsaponifiable matter of a lipid and in determining the alkanols of extra-virgin olive oil, husk oil and their relative mixtures. The proposed procedure permits the study of alkanols without having to isolate them from the other classes of compounds present in the unsaponifiable matter by means of thin-layer chromatography.     

注射用伏立康唑专用溶剂的气相色谱含量测定

以四氢呋喃为溶剂,甲苯为内标,采用以OV-101为固定相的毛细管气相色谱柱(30m×0.22mm),氢火焰离子化检测器,建立注射用伏立康唑专用溶剂中乙醇和丙二醇的气相色谱定量分析方法。两种溶剂的平均回收率(n=9)分别为99.32%±1.1%、99.96%±2.0%;对应的检出限分别为0.05、0.3nL;在2~50μL/mL浓度范围内,各组分线性关系良好(r=0.9999)。     

A simplified gas liquid chromatographic determination for vitamin E in vegetable oils

A simple and rapid procedure has been developed for the isolation, concentration, esterification, and gas liquid Chromatographic (GLC) quantitation for the Vitamin E content of vegetable oils. Vitamin E is determined by saponification of the oil, ether extraction of the saponified mixture, drying and evaporation of the extract, followed by closed tube esterification and quantitation of the butyrate ester using a gas Chromatograph equipped with a hydrogen flame ionization detector. This technique eliminates the conventional thin layer Chromatographie isolation of Vitamin E normally used prior to direct or trimethylsilyl (TMS) derivative GLC quantitations. Oils fortified with Vitamin E in the 5 to 40 milligrams per 100 grams range showed recoveries of 93.4 to 98.6%.     

毛细管气相色谱法同时测定三磷酸胞苷二钠中5种有机溶剂残留量

研究建立了同时测定三磷酸胞苷二钠中乙醇、丙酮、氯甲醚、甲苯、苯乙烯5种有机溶剂残留量的毛细管气相色谱法。样品以乙腈为溶剂,经DB-FFAP(30 m×0.32 mm×0.25μm)毛细管柱分离,氢火焰离子化检测器检测,这5种有机溶剂呈良好的线性响应,平均回收率在98.3%~99.5%,精密度RSD在0.21%~1.92%,最低检出限可达5.0~7.5 mg/kg。本方法简单、灵敏、准确,完全能满足药品中所述有机溶剂残留量的测定要求。     

A gas chromatographic method for the determination of mass-transfer resistances in zeolite catalysts

The various mass-transfer resistances that occur in a packed bed of zeolite granules contribute to the gas chromatographic “C” terms that determine the relative width (or second moment) of a gas chromatographic peak. It was assumed that mass transport in the micropores of the crystallites was independent of the nature of the carrier gas. From measurements with hydrocarbon pulses in hydrogen and nitrogen carrier gases, it was possible by the method of Giddings and Schettler to separate the gas phase resistances from the micropore resistances. Data are given for benzene, n-octane and (in part) n-decane on Na × zeolite at 370, 400 and 430°C. Experimental difficulties and precautions are discussed.     

Simultaneous quantification of serum phytosterols and cholesterol precursors using a simple gas chromatographic method

Determination of the main phytosterols (Ps, β‐sitosterol and campesterol) and cholesterol precursors (desmosterol and lathosterol) in human serum using a simple GC‐FID method has been validated. Direct saponification, without lipid extraction, sterols extraction, and further derivatization was applied to samples prior to GC analysis. To evaluate the method, a pool of serum samples from eight healthy women was used. Good linearity (r>0.99) was found in the assay range: β‐sitosterol (0.99–17.82 µg/mL), campesterol (0.14–10.8 µg/mL), desmosterol (0.17–2.6 µg/mL), and lathosterol (0.6–5.97 µg/mL). Limits of detection (ng/mL) were: 86 (β‐sitosterol), 42 (campesterol), 4 (desmosterol), and 44 (lathosterol). Accuracy, estimated by recovery assays (%), were: 113 (β‐sitosterol), 114 (campesterol), 111 (desmosterol), and 102 (lathosterol). Within and between precision values (%), expressed as the relative SD (RSD), were: 2.6 and 8.1 (β‐sitosterol), 1.6 and 7.2 (campesterol), 2.1 and 7.9 (desmosterol), and 4.1 and 5.8 (lathosterol), respectively. The developed methodology allowed fast (1‐day analysis) and reliable quantification of sterols in serum, required a small volume of sample and reduced use of solvents. It therefore could be used in clinical assays for the determination of serum sterols, as in evaluating the pharmacological response to lipid‐lowering agents, and in assessing biological responses to Ps‐enriched diets. Practical applications : This methodology allows fast and reliable quantification of sterols in serum, requiring a small volume of sample and reduced use of solvents. It can be used as a routine method for the quantification of phytosterols and cholesterol precursors in clinical assays, and it is also suitable for monitoring biological responses to health‐promoting phytosterol‐enriched diets.     

气相色谱法检测煤气中氧气含量的测量不确定度评定

利用气相色谱法对煤气中氧气含量进行检测,通过应用现代数理统计方法对煤气中氧气含量测量不确定度来源进行分析,同时从标准样品、标准样品峰面积和混合气体样品峰面积等几大方面对测量不确定度来源进行了分析和量化评定,指出主要的不确定度来源是标准物质、测量重复性和仪器校准时的示值误差.并计算出相对合成不确定度,得出煤气中氧气体积分数为Ψ(O2)=(0.87±0.04)％,(k=2).     

A practical headspace gas chromatographic method for the determination of oxalate in bleaching effluents

This paper reports an improved headspace gas chromatographic (HS-GC) technique for the determination of oxalate content in bleaching effluents. The method is based on the redox reaction between potassium iodate and oxalate, from which the carbon dioxide is generated and measured by HS-GC. The results showed that the reaction in a sulfuric acid solution (0.05 mol/L) was complete in 35 min at 95 °C. The RSD of the method in the repeatability testing was less than 4.5%, the LOQ was 0.35 μg, and the recovery ranged from 95 to 103%. The present method is simpler, more reliable, and more practical compared to the methods reported previously.     

The application of packed column gas chromatographic analysis to the determination oftrans unsaturation

A study of the separation of synthetic mixtures ofcis andtrans methyl octadecenoate with packed column gas chromatography indicated its usefulness for such analyses. Several margarines were analyzed by this method and the results compared with those obtained by the infrared spectroscopic method. Reasonable agreement between both methods was obtained, but the gas chromatographic determination yielded lower values (average 3.8%). The presence oftrans unsaturation was also shown in selected samples of human milk and blood lipids.     

A rapid gas chromatographic method for the determination of BHA and BHT in vegetable oils

A gas liquid chromatographic (GLC) technique has been developed which requires about 20 min for the determination of BHA and BHT in vegetable oils. This method involves the addition of an internal standard to a weighed portion of the oil, dilution of the mixture with carbon disulfide, and injection into the Gas Chromatograph. BHA and BHT are isolated from the nonvolatile vegetable oil by using a short precolumn located in the sample port block of the gas chromatograph. Up to 35 consecutive sample injections per day have been made on the same precolumn with no appreciable effect on the accuracy of the determination. The precolumn is cleaned at the end of each day’s operation. The clean precolumn is allowed to equilibrate to sample port block temperature overnight for the following day’s analysis. Identification of BHA and BHT can be confirmed with a second GLC column which reverses the elution order of these compounds. Soybean, cottonseed, corn and peanut oils fortified with 20, 60 and 100 ppm each of BHA and BHT showed a recovery range of 97% to 104%.     

Pyrolysis gas chromatographic analysis of polyacrylonitrile

Pyrolysis gas chromatographic analysis of polyacrylonitrile under an inert atmosphere was made in a temperature region of 500–900°C. It was confirmed that the main degradation products are various kinds of lower nitriles that include CH₂CHCN, CH₃CN, and HCN. In addition, lower hydrocarbons such as CH₄ and C₂H₄, which are related to secondary decomposition, were detected. Various thermo‐analytical data were obtained, including those concerning the relation between retention time and the polarity of nitriles, and the dependence of the products' limiting yield on pyrolysis temperature. Based on the above results, specific applications of the pyrolysis gas chromatographic analysis and the utility of this procedure in the study of thermal degradation of polyacrylonitrile are described. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 473–478, 2001     

气相色谱固定相的演变

简要综述了半个世纪以来气相色谱固定相的发展,在气相色谱发展的初期主要是低分子化合物和工业用高聚物,主要用于填充柱气相色谱,有上千种固定液。到上世纪80年代以后毛细管柱气相色谱起主导作用,固定液数量减少、质量提高,最常用的有五六种。到上世纪90年代以后固定相的研究以手性固定相和提高常规固定相的性能为主。进入21世纪,各个制备色谱柱的公司不断推出高性能、低流失、重复性好和专用型毛细管柱色谱柱,以适应研究和实际需要。     

Quantitative high-resolution gas chromatographic determination of stereoisomeric composition of chiral volatile compounds in the picogram range by ec-detection

A gas chromatographic method using electron capture detection for determination of the stereochemical composition of chiralolatile compounds, e.g., pheromones, at the picogram level is described. Substances of interest are analyzed as pentafluorobenzoate derivatives on fused silica capillary columns coated with CP Sil-88. This method was developed primarily for the quantitative analyses of stereoisomerism of the pheromone precursor, diprionol, in female sawflies,Neodiprion sertifer. It was possible to separate the stereoisomers showing (2S, 3S, 7R) and (2S, 3S, 7S) configurations. Resolution of the (2S, 3S, 7S)- and (2S, 3R, 7R)-diastereomers was high enough to allow the quantification of these stereoisomers. A quantitative analysis of the diprionol production in individualN. sertifer females yielded 7.5–9.7 ng/female.     

气雾杀虫剂产品中右旋苯醚氰菊酯的气相色谱测定

建立了用气相色谱外标法分析气雾杀虫剂产品中右旋苯醚氰菊酯的方法。色谱条件:色谱柱为DB170130m×0.32mm,检测器为火焰离子化检测器,在DB1701色谱柱上右旋苯醚氰菊酯能与其它组分很好的分离,分离度(α)>2.0。右旋苯醚氰菊酯的浓度在1.0￣0.00010mg/ml范围内呈现良好的线性关系,r=0.9999;检测限为1.0μg/g。方法的回收率为93.6%￣103.2%。该法操作简便、快速、准确性高、重复性好,对同一样品的5次平行测定的相对标准偏差(RSD)<3.0%,可作为本品的质量控制方法。     

A method for the quantitative estimation of cholesterol α-oxide in eggs

A method for the quantitation of cholesterol α-oxide in egg and egg products is described. Total lipids extracted from dry egg samples were fractionated on a silicic acid column to concentrate cholesterol oxides which were then quantitatively determined by gas liquid chromatography (GLC). Those samples which showed cholesterol oxides by GLC were further analyzed by high pressure liquid chromatography (HPLC) for the ratio of cholesterol α-oxide and cholesterol β-oxide. Cholesterol α-oxide content was calculated from the combined results of GLC and HPLC.     

毛细管气相色谱柱近年的发展

简要地阐述了近几年毛细管气相色谱柱的发展和特点.GC的色谱柱制柱工艺是一个成熟的技术,所以在制柱工艺方面的研究不够活跃.近年新研究的固定相集中在常温离子液体和各种环糊精的衍生物.20世纪GC毛细管色谱柱柱工艺的研究主要在研究机构和学校中进行,而近几年GC毛细管色谱柱的研究和改进集中在色谱柱厂家进行,并立即成为商品柱.近年GC分析所用的色谱柱大都使用毛细管柱,并趋向于使用商品GC毛细管柱,所使用的商品色谱柱中,最多的是以含5%苯基的聚甲基硅氧烷色谱柱.     

Selective effect of cholesterylphosphoserine on intracellular cholesterol transport

Cholesteryl-3β-phosphoserine (CPHS) is a synthetic steroid affecting intracellular cholesterol transport. To compare CPHS with the well-known inhibitors progesterone and U18666A, we examined cholesterol transport in three human cell lines: the monocytic U-937, the endothelial ECV-304, and the lymphoid Jurkat. Under low density lipoprotein (LDL) loading, CPHS inhibited cholesterol esterification in U-937 and ECV-304 cells but not in Jurkat cells. In contrast, CPHS inhibited the mobilization of plasma membrane cholesterol induced by 25-hydroxycholesterol, brefeldin A, or sphingomyelinase in all cell lines. In cells pulse-labeled with [³H] cholesterol, CPHS decreased incorporation of cholesterol and inhibited its esterification. In prelabeled cells, CPHS promoted cholesterol efflux and enhanced the cyclodextrin-mediated removal of plasma membrane cholesterol. CPHS did not affect endogenous cholesterol synthesis nor acylcoenzyme A: cholesterol acyltransferase activity. These data suggest that, unlike progesterone and U18666A, CPHS inhibits intracellular cholesterol transport by specifically affecting the movements of cholesterol in the plasma membrane. Owing to this restricted site of action, CPHS may help to clarify the role of the plasma membrane in cholesterol trafficking. For example, the lack of an effect of CPHS on the esterification of LDL-derived cholesterol in Jurkat cells suggests that most of the LDL-derived cholesterol in these cells is directly delivered to the endoplasmic reticulum without cycling through the plasma membrane.