Determination of 11 Sulfonamide Residues in Pork by Modified Fluorescamine Precolumn Derivatization-High Performance Liquid Chromatography with Fluorescence Detection

An analytical method using high performance liquid chromatography (HPLC) with fluorescence detection after modified precolumn derivatization with fluorescamine was established for the determination of 11 sulfonamide residues in pork. The optimized reaction conditions were as follows: 0.8 mL of phosphate buffer (0.1 mol/L, pH 3.0) and 0.2 mL of fluorescamine solution (0.3 mg/mL) were mixed, vortexed, and kept in darkness at 4 ℃ for 40 min. The derivatization method was stable and reliable and the resulting product was stable for 12 h at 4 ℃. The sample was extracted with 0.1 mol/L phosphate buffer solution, purified by an HLB solid phase extraction column, and then derived by this method, before being analyzed by HPLC. The calibration curves for the 11 sulfonamides showed a good linear relationship in the concentration range between 1 and 200 μg/L with a correlation coefficient higher than 0.9994. The limit of quantification for the analytes was 0.8–1.6 μg/kg. At spiked concentrations of 2, 50 and 100 μg/kg, the developed method showed excellent recoveries ranging from 62.0% to 108.0% with intra- and inter-relative standard deviations (RSDs) of 2.0% to 8.8% and 1.8% to 8.6%, respectively.