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151.
Summary A derivatization procedure for the gas chromatographic analysis of bifunctional amines likeβ-adrenergic blocking drugs is described. The method consists of a two-step reaction with methyldichlorophosphine and sulfur
in presence of triethylamine to form cyclic methylphosphonothioic derivatives. The properties of these compounds are discussed
and the application of the method to the quantitation of ephedrine in human body fluids is presented.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
152.
V. G. Berezkin V. R. Alishoyev E. N. Victorova V. S. Gavrichev V. M. Fateeva 《Chromatographia》1982,16(1):126-131
Summary The use of crystallohydrates, crystallohydrate solutions and melts as stationary phases in gas chromatography has been proposed. Crystallohydrates have been shown to display high selectivity in the separation of polar organic compounds when use is made of water vapours as the mobile phase. Some aspects of gas-liquid chromatography in water vapours and with the stationary phase comprising crystallohydrates have been studied, and the preliminary results obtained point to the desirability of further progress in this field.Presented at the 14th International Symposium on Chromatography London, September, 1982 相似文献
153.
154.
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156.
E. L. Anderson M. M. Thomason H. T. Mayfield W. Bertsch 《Journal of separation science》1979,2(6):335-342
A versatile two-dimensional gas chromatograph is described, consisting of 2 separate ovens, one intermediate trap, an auxiliary inlet, and the necessary hardware to effect off-line switching according to the principle of Deans. The unit has been designed for use with high resolution glass capillary columns. The performance of individual instrumental components was critically evaluated. Results showed that low dead volume glass to metal connections were required in the manifold and detector lines to minimize extra-column effects. The mass of the intermediate trap must be low to allow rapid heating. Operational parameters are discussed and examples of some applications are shown. 相似文献
157.
Gas Chromatographic Method for Routine Determination of Oleanolic and Ursolic Acids in Medicinal Plants 总被引:1,自引:0,他引:1
Summary A rapid and simple gas chromatographic method has been established for routine analysis of free oleanolic and ursolic acids in dried samples of medicinal herbs. Soxhlet extraction of triterpenes was followed by solid-phase extraction (SPE). Amounts of the compounds were measured by gas chromatography after silylation of the purified samples. Experiments were performed to establish the optimum conditions (e.g. solvent, and mode and duration of extraction) for calibration curve linearity, sensitivity, reproducibility, and recovery. The conditions used for derivatization and gas chromatographic analysis resulted in an improvement on literature data. The method devised enables accurate routine measurement of many samples in quite a short time (e.g. for chemotaxonomical screening, or quality control of herbal drugs). The practical application of the method was illustrated on five Lamiaceae species. 相似文献
158.
建立了气相色谱过程的动态数学模型,给出了模型的实用算法,并据此对各种操作条件下的色谱流出曲线进行了动态模拟计算。模拟计算结果表明该模型是有效的,能够用于各种程序控制的色谱过程,可得到色谱分离的优化条件。 相似文献
159.
土壤中绿黄隆残留量分析方法的研究 总被引:2,自引:0,他引:2
本文确立了土壤中绿黄隆残留量的间接气相色谱分析方法,用0.15mol/L NaHCO3提取土样,二氯甲烷洗涤初步纯化后,在水浴上加热水解,再用二氯甲烷萃取,弗罗里硅土柱净化,最后用气相色谱-电子捕获检测器检测水解产物邻氯苯磺酰胺。土壤中添加回收率78.5%-90.8%,检测极限0.3ng/g。 相似文献
160.
《Chemphyschem》2004,5(2):175-182
The selectins are Ca2+‐dependent cell adhesion molecules that facilitate the initial attachment of leukocytes to the vascular endothelium by binding to a carbohydrate moiety as exemplified by the tetrasaccharide, sialyl Lewis X (sLeX). An important property of the selectin‐sLeX interaction is its ability to withstand the hydrodynamic force of the blood flow. Herein, we used single‐molecule dynamic force spectroscopy (DFS) to identify the molecular determinants within sLeX that give rise to the dynamic properties of the selectin/sLeX interaction. Our atomic force microscopy (AFM) measurements revealed that the unbinding of the selectin/sLeX complexes involves overcoming at least two activation barriers. The inner barrier, which determines the dynamic response of the complex at high forces, is governed by the interaction between the Fuc residue of sLeX and a Ca2+ ion chelated to the lectin domain of the selectin molecule, whereas the outer activation barrier can be attributed to interactions involving the sialic acid residue of sLeX. Due to their steep inner activation barriers, the selectin‐sLeX complexes are less sensitive to high pulling forces. Hence, besides its contribution to the bond energy, the Ca2+ ion also grants the selectin–sLeX complexes a tensile strength that is crucial for the selectin‐mediated rolling of leukocytes. 相似文献