Determination of Nitrofuran Metabolites in Fishery Water by Microwave Assisted Derivatization and Liquid Chromatography-Tandem Mass Spectrometry

A method based on microwave-assisted derivatization (MAD) with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for determination of 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethy-2-oxazolidinone (AMOZ), semicarbazide (SEM), 1-aminohydantoin (AHD) and 3,5-dinitrosalicylic acid hydrazide (DNSAH) in fishery water. The sample was extracted with ethyl acetate, then was derivatized with 2-nitrobenzaldehyde using microwave assisted method for 1 min. The analysis was carried out on an Acquity UPLC BEH C18 column by gradient elution with acetonitrile-ammonium acetate (5 mmol/L, 0.1% formic acid) as mobile phase, and was detected by LC-MS/MS system with positive and negative electrospray ionization under multiple reaction monitoring (MRM) mode. The results show that the metabolites have good linearity in the range of 0.2-50 μg/L, and the correlation coefficients (R²) are better than 0.997. The limits of quantification (LOQs) of the five targets are in the range of 0.02-0.05 μg/L. The average recoveries range from 79% to 102% for the five targets at three spiked levels with the relative standard deviations of 3.6%-10.1%. The method is proved to be fast and effective for simultaneously qualitative and quantitative inspection of the metabolites of nitrofuran in fishery water.