Abstract:

A sample preparation and analytical method with accelerated solvent extraction (ASE) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed to detect 19 antibiotic (9 sulfonamides, 4 quinolones, 3 macrolides and 3 others) and 2 sulfonamide metabolite residues in fish muscle. The target compounds were extracted using ASE and purified simultaneously by a C18 resin in the extraction cell. The extracts were evaporated to dryness, and redissolved with the initial mobile phase for HPLC-MS/MS analysis after freezing centrifugation (10000 r/min, -4 ℃) to remove the fat and other matrix compounds further. The separation of the analytes was carried out on an Xterra MS C18 column with methanol-acetonitrile (1:1, v/v) as mobile phase A and 0.1% formic acid (containing 0.1% ammonium formate) as mobile phase B. The spiked recoveries of the method were 55.2%-113.3%, with the relative standard deviations of 0.1%-17.6%(n=6). The limits of detection ranged from 0.003 to 0.6 ng/g. The method was applied to two fish (Synechogobius hasta and Liza haematocheilus) collected in mariculture areas of Laizhou Bay and six antibiotics were detected, in which the mass concentrations of norfloxacin were highest with mean values of 67.01 and 27.58 ng/g, respectively. The method is simple, rapid, highly sensitive, and useful in the study on exposure levels and environmental behavior of the antibiotics.

Key words: accelerated solvent extraction (ASE), antibiotics, fish, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), mariculture, residues, sulfonamide metabolites