Optimization of determination of nitrofuran metabolites in aquatic products by liquid chromatography tandem mass spectrometry

The nitrofuran metabolites (AMOZ, SEM, AHD and AOZ) were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS) in aquatic products. The sample pretreatment method and chromatographic conditions were optimized. The sample pH value was adjusted to 7.0~7.5 after derivation. Then the analytes were extracted by 8 mL ethyl acetate. Following centrifugation, the supernatant was transferred and evaporated to dryness under a gentle stream of nitrogen at 40 ℃. The residues were redissolved in 1 mL mobile phase of acetonitrile and 0.1% formic acid (5/95, V/V), and then centrifuged at 20 000×g for 10 min at 4 ℃. Gradient elution for LC separation was performed by using acetonitrile and 0.1% formic acid in water solution, and four nitrofuran metabolites were excellently separated with a C₁₈ column. This accurate optimized method can promote efficiency greatly and is suitable for lot determination of nitrofuran metabolites in aquatic products.