Sensitive Residue Analysis of Quinolones and Sulfonamides in Aquatic Product by Capillary Zone Electrophoresis Using Large-Volume Sample Stacking with Polarity Switching Combined with Accelerated Solvent Extraction

A simple and sensitive capillary zone electrophoretic method for the residue determination of lomefloxacin, enoxacin, sarafloxacin, enrofloxacin, sulfadiazine, sulfamethoxydiazine, and sulfadimethoxypyrimidine was developed. Accelerated solvent extraction with acetonitrile as solvent at 80 A degrees C and 10.3 MPa was used for sample preparation. On-column preconcentration using large-volume sample stacking with polarity switching was applied for sensitivity enhancement. The standard curves for the determination of the seven residues have good linearity (r > 0.999). The method limits of quantification (LOQs) were 13.2-20 mu g kg(-1) for the quinolones and 8.0 mu g kg(-1) for the sulfonamides. Intraday and inter-day precisions (RSDs) at 100 mu g kg(-1) level were 1.4-4.1 and 2.3-4.7 %, respectively. The residue determination of the quinolones and sulfonamides in aquatic products was achieved. Their average recoveries for three spiked levels (50, 100, and 500 mu g kg(-1)) were 85.4-95.7 % with the RSD of 1.1-4.7 % for shrimp sample and 84.3-94.8 % with the RSD of 1.4-4.5 % for sardine sample. The proposed method provides a rapid and simple extraction procedure, satisfactory repeatability, and reproducibility, as well as high accuracy, and can permit the routine detection of the studied drug residues in aquatic product at the content below or above the MRL.