SIMULTANEOUS DETERMINATION OF EPHEDRINE AND ITS ANALOGUES IN URINE BY CAPILLARY GAS CHROMATOGRAPHY

A method is developed for the simultaneous determination of ephedrine,pseudoephedrine, norephedrine, norpseudoephedrine and methylephedrine in urine on a capillary column using nitrogen-phosphorus detector.Diphenylamine is used as the internal standard.Calibration graphs are linear down to 1.30ug/ml urine.

Biodiesel Production by Enzymatic Catalysis Process Using Two Analytical Ways： Gas Chromatography and Total Glycerol Determination

Currently, biodiesel is presented as one of the best alternatives for gradually replacing the use of fossil fuels, but it has some factors that make it economically impractical if it does not have a government support. For this reason, research efforts focused on this area have been responsible for optimizing the process of biodiesel production by different catalytic routes to achieve greater efficiency at a lower cost. In this case, the biggest problem has been the high cost generated by an investigation, which in many occasions is the main factor to decide if an investigation could be carried out. Trying to reduce these costs, in the current study, we are using a technique of glycerol quantification by volumetric methods and comparing obtained results with the chromatographic method, which is conventionally used and comparatively much more expensive. Biodiesel employee was obtained by an enzymatic catalysis process varying one of three process variables：oil：alcohol molar ratio, temperature and proportion of catalyst. The numerical differences obtained between the two quantification methods generated relative errors lower than 10%, resulting in some occasions lower than 1%. By gas chromatography analysis the best yield was obtained at the same conditions of the volumetric method, a temperature of 45 ℃, an oil：alcohol ratio 1：4 and 8 wt.% of catalyst, but a yield of 95.5% and 97.1%, respectively. Due to the high precision of gas chromatography, this method is used to carry out a surface response analysis obtaining as ideal operating conditions a temperature of 43.5 ℃, 8.9 wt.%. of catalyst and an oil：alcohol ratio 1：4.

Rapid Determination of Pesticide Residues in Fresh Sweet Corn

Objective] This study aimed to detect al organophosphate, organochlorine and pyrethroid pesticide residues in fresh sweet corn in one determination using a gas chromatograph. [Method] The pesticide residues in fresh sweet corn were ex-tracted and loaded to simultaneously the gas chromatograph Agilent 6890N which was equipped with two autosamplers, two columns and two detectors. [Result] Al the 26 pesticides were completely separated and eluted out within 25 min. The re-coveries of standard addition of the 26 pesticides ranged from 76% to 106%, with relative standard deviations （RSD） ranging from 0.5% to 8.9%. The linear regression equation fit wel from 0.050 to 1.500 mg/L corn extract （r2＆gt;0.996）. [Conclusion] The method is accuracy, which meets the requirements of pesticide residue analysis and can be used for the rapid detection, qualitative and quantitative analysis of pesticide residues in fresh sweet corn.

高效液相色谱法测定丙溴磷

利用高效液相色谱法时丙溴磷进行了分析测定。本实验选择μＢｏｎｄａｐａｋＣ＿（１８）色谱柱、甲醇：水（８２：１８，ｖ／ｖ）作流动相和ＵＶ～２８０纳米检测等色谱条件，使丙溴磷得到了较好地分离。本方法定量测定的回收率为９８．８２％（ｎ＝６），变异系数为３．１２％。实验结果表明，本方法是一种快速、简便、灵敏度高、重现性较好的测定方法。

溴丙磷的气相色谱分析

采用气相色谱法测定溴丙磷原药及制剂的含量。选用５％ＯＶ－１０１／ＧａｓＣｈｒｏｍＱ（８０～１００目）色谱柱，以邻苯二甲酸二丁酯为内标物，三氯甲烷为溶剂，用氢火焰离子化检测器测定。其回收率在９８．６～１００．４％，原油和乳油的变异系数分别为０．４２％和０．４８％。

Comparative Analysis and Validation Methodologies of GC and HPLC for Analysis of Cholesterol in Meat Products

This study validated different extraction methodologies and compared the quantification of cholesterol by gas chromatography (GC) and high performance liquid chromatography (HPLC) in mg per 100 g of Italian-type salami and traditional bologna. The GC method used was direct saponification of the samples without derivatizations and the HPLC method was used to extract of the lipid samples. The GC limits of detection and quantification obtained for cholesterol were, respectively, 0.001 and 0.003 mg.g–1. The HPLC values were 0.005 mg.g–1 and 0.016 mg.g–1. The GC recovery rate was 97.10 ± 0.13 and that of HPLC was 93.33 ± 0.22. Comparison of the cholesterol quantity found using the two chromatographic techniques shows that both are capable of quantifying cholesterol in the foods. With regard to costs, analysis time, the cost/benefit relationship was better with gas chromatography than that obtained with high performance liquid chromatography.

丙溴磷的气相色谱分析

用３％ＯＶ－２１０的气相色谱填充柱，以磷酸三苯酯为内标，用具有氢焰离子化检测器的气相色谱仪对丙溴磷原药和乳油进行定量分析。原药和乳油的标准偏差分别为０２１和０２３，平均变异系数分别为０２５％和０５４％，平均回收率分别为９９４％和１００６％，此法操作简便，定量准确。

血液中丙溴磷检测方法研究

目的研究血液中有机磷农药的气相色谱测定方法,完善检测过程,优化检测条件,建立简便高效的提取净化方法和准确、快速、灵敏的色谱检测方法。方法将中毒血样经乙酸乙酯萃取后,用毛细管气相色谱法测定其含量。结果分析方法的检出限为0.8ng,低、中、高三种浓度的加标回收率为95.4%±5.85%、91.2%±11.5%、92.8%±5.5%。结论该方法灵敏、准确、可靠,适合人血液中丙溴磷的检测。