Pressurized Capillary Electrochromatography For Residues Analysis Of Pecticides And Veterinary Drug In Eggs

With the intensification and development of livestock and agriculture, the scope of the application of pesticide and veterinary drugs is expanding. The quality of the agricultural products has been seriously affected by the pesticides residues of the organic nitrogen, organic phosphorus, pyrethroids, carbamates and veterinary drug residues of antibiotic, sulfa drug and etc. Nowadays the control and monitoring of toxic contaminanta in food is an issue of primary health importance. As veterinary medicine uses getting more and more in the animal husbandry, the medicine residues in the foodstuffs become the focal point. Therefore, it is necessary to develop reliable and accurate analytical methods for establishing safe maximum residues limits for residues of these substances in animal tissues and derived foodstuffs entering the human food chain such as meat and eggs.It has brought about the necessity of developing new analytical techniques for a wide variety of food contaminants including pesticides and veterinary drugs. The prospects for capillary electrokinetic separation techniques in this type of analysis are very promising because of its advantages, such as high efficiency, high resolution, high selectivity and high peak capacity in addition to their fast speed, and very low consumption of sample and solvents.This thesis consists of five chapters. In chapter one, an overview of residues analysis methods in food is presented.The chapter 2 deals with the application of pCEC technique for the analysis of pesticides and veterinary drug in egg samples. Under the optimum condition, four N-methylcarbamat insecticides were baseline separated . the detection limits (S/N=3) for the carbamate pesticides were 4μg/mL (Aldicarb),2.5μg/mL (Metolcarb),2.5μg/mL (Carbofuran),and 1μg/mL (Sevin), respectively. The recoveries obtained from the analysis of spiked eggs samples were between 86.95% and 104.20% with the relative standard deviation lower than 9.91%. The method is simple, rapid and reproducible. This developed method was successfully applied to the quantitative analysis of four N-methylcarbamat insecticides and veterinary drugs in food, which is helpful to its quality control. In chapter 3, a simple, rapid and reproducible anaytical method of pressiurized capillary electrochromatography using a reversed phase column (C18) was applied to the separation and determination of four tetracyclines insecticides in eggs. The optimum condition was: mobile phase: 10 % (v/v) methyl alcohol, 20% (v/v) acetonitrile and 70% (v/v) of a 20 mmol/L aqueous buffer at pH 2.45; UV detection at 270 nm. The linear ranges for the four tetracyclines with R2 more than 0.993 were satisfactory. The recoveries obtained from the analyses of spiked eggs were between 80.46% and 100.49% with a relative standard deviation lower than 13.81%.In chapter 4, an isocratic pCEC system was used to separate and determine four sulfonamides by using a sulfoalkylbetaine-based monolithic stationary phase with mixed-mode of HI / SAX separation. On a capillary column of sulfoalkylbetaine-based monolithic stationary phase by using a mobile phase consisting of 35% v/v ACN and 65% v/v of 30 mmol/L ammonium formate (pH 4.5). Under the optimum conditions four sulfonamides were completely separated within 20 min. The linear ranges of the four tetracyclines method were satisfactor. The calibration curve had a rather good linearity with R2 more than 0.993. The method had satisfactory linear correlation, precision, and recovery. The recoveries of 80.46% and 100.49% for four kinds of eggs samples at different concentrations of tetracyclines with RSD less than 5% were obtained, respectively. This method is simple, rapid and reproducible, and can be applied to the quantitative analysis of tetracyclines insecticides and veterinary drugs in eggs.In chapter 5, a simple pCEC methods with solid phase extraction (SPE) preconcentration were developed for three estrogen residues analysis in egg samples with satisfying recoveries, which proved to be a rapid and cost-effective method for the determination of contaminants in food.In chapter 6, a rapid method was developed for the determination of trace sulfonamides in eggs samples.4 sulfonamides derivatized with FITC were determined with the application of pCEC technique. It was found that introduction of the electrical field, the supplementary pressure, and salt in the mobile phase, greatly improved the speed, selectivity, and repeatability of analysis. Limits of the detection for the studied analytes were lower than or close to the official maximum residue limits (MRLs), usually in the sub-ppm level.