Determination Of Four Animal Drug Residue By Capillary Electrophoresis With Online Concentration And Fluorescent Spectrophotometry

Sweeping is a kind of online concentration technique in micellar electrokinetic capillary chromatography, which can improve the detection limit of capillary electrophoresis.The online enrichment of norfloxacin can be carried out by sample sweeping technique in capillary electrophoresis. A new method of capillary electrophoresis based on this principle was developed to determine residue norfloxacin in chicken meat. The influencing factors of analyte peak height, such as the separation voltage, kind and concentration of electrolyte in running buffer, pH of running buffer, SDS concentration in running buffer, injection pressure, methanol concentration in running buffer and methanol concentration in sample, were optimized. And the optimum conditions were as follows: The concentration of borax, SDS and methanol in running buffer was 120 mmol/L, 110mmol/L and 10 %, respectively. The pH of running buffer was 9.30 and the separation voltage was 12.5 kV. The methanol in sample was 10 %, and the injection pressure was 2750.2 kPa×s. Under the optimum conditions mentioned above, the peak concentration of norfloxacin was enriched for 692-fold, and its detection limit was lowered to 30μg/L. The linear dynamic range of calibration curve was from 50 to 9000μg/L.The method had been applied to the detection of norfloxacin in chicken meat purchased from the market; the recoveries of spiked sample were between 81.29 % and 87.06 %.Enoxacin and levofloxacin can emit intense fluorescence in the citrate buffer adjusted to pH3.65 when the SDS concentration in the buffer is 80 mmol/L. The two analytes can be simultaneously determined by means of the proper selection for exciting wavelength and emitting wavelength. Under the optimum conditions, the detection limits were 2.90μg/L for enoxacin and 2.11μg/L for levofloxacin, and the linear dynamic ranges were 50μg/L～600μg/L for enoxacin and 25μg/L～350μg/L for levofloxacin, respectively. The method had been applied to the determination of enoxacin and levofloxacin in milk, and the recoveries of spiked sample were 101.29%～113.67 % for enoxacin and 85.63%～91.93 % for levofloxacin.Albendazole can emit intense fluorescence in the phosphate buffer. The fluorescence can be enhanced for about 5-folds by means of the protecting action of SDS micellar. The assay of albendazole should be carried out in pH 2.12 buffer consisting of 50 mmol/L phosphate and 20 mmol/L SDS. Under the optimum conditions, its detection limit was 10μg/L, and the linear dynamic ranges was 125μg/L～2000μg/L. The method had been applied to the determination of albendazole in milk, and the recoveries of spiked sample was 80.07%～85.01%.