Determination Of Three Pesticide Residue By Capillary Electrophoresis With Online Concentration And Fluorescent Spectrophotometry

Stacking is a kind of online sample concentration technique in capillary zone electrophoresis, which is based on the differential electrophoretic velocity of the solute. Sweeping is a kind of online concentration technique in micellar electrokinetic capillary chromatography, which is based on the differential partition of the solute in the pseudostationary phase. They can also improve the detection limit of capillary electrophoresis.The online enrichment of chlordimeform was carried out by capillary electrophoresis sample stacking technique. A new method of capillary electrophoresis to determine residue chlordimeform in honey was developed by means of capillary electrophoresis sample stacking technique. The influencing factors of analyte peak height, such as the phosphate concentration, methanol concentration and pH of running buffer, separation voltage, methanol concentration in sample and injection time, were optimized. And the optimum conditions were as follows: The concentration of phosphate and methanol in running buffer was 50.0mmol/L and 50%, respectively. The pH of running buffer was 6.12, and the separation voltage was 10KV. The methanol in sample was 80%,and the injection time was 40s.Under the optimum conditions mentioned above, the peak concentration of chlordimeform was enriched for 1810-fold, and its detection limit was lowered to 1.12 X 10~-3 mg/kg. The linear dynamic range of calibration curve were from 2.2μg/L to 11μg/L. The method has been applied to the detection of chlordimeform in honey that was bought in the market;the recoveries of spiked sample were between 95.5% and 103.0%, and the results show adequate accuracy and precision.The online enrichment of omethoate was carried out by capillary electrophoresis sample sweeping technique. A new method of capillary electrophoresis to determine residue omethoate in Chinese cabbage was developed by means of capillary electrophoresis sweeping technique. The influencing factors of analyte peak height, such as the borax concentration, micellar concentration ,methanol concentration and pH of running buffer, separation voltage, methanol concentration in sample, injection voltage and injection time, were optimized. And the optimum conditions were as follows: The concentration of borax, CTAB and methanol in running buffer was 80.0mmol/L, 6.0 mmol/L and 10%, respectively. The pH of running buffer was 10.22, and the separationvoltage was 7KV. The methanol in sample was 80%, the injection voltage was 7KV and the injection time was 120s. Under the optimum conditions mentioned above, the peak concentration of omethoate is enriched for 270-fold, and its detection limit was lowered to 4.5 X 10"4mg/kg. The linear dynamic range of calibration curve were from 0.18 mg/L to 18mg/L. The method has been applied to the detection of omethoate in Chinese cabbage that were bought in the market;the recoveries of spiked sample were between 90.2% and 94.7% .Amitraz can be hydrolyzed as 2, 4-xylidine with strong fluorescence. Based on the principle, the fluorescent analytical method of determining residue Amitraz is developed. The detection limit of Amitraz is 1.44ug/L, and its linear dynamic ranges are 3.59-1174ug/L. The recoveries of spiked sample are 82.7%~86.3%. The method has been applied to the determination of residue Amitraz in pear.