Rapid determination of multiple prohibited and restricted veterinary drug residues in fish and shrimp by ultra high performance liquid chromatography-tandem mass spectrometry

Abstract

A method was established for the rapid determination of 28 prohibited and restricted veterinary drugs of five classes (sulfonamides, quinolones, chloramphenicols, nitrofurans metabolites and triphenylmethane) in fish and shrimp by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) coupled with simultaneous extraction and purification. After optimizing the sample pretreatment methods and chromatographic conditions, the samples were hydrolyzed with hydrochloric acid. The five kinds of residual drugs were simultaneously extracted with acetonitrile after nitrofuran metabolites derivatized with 2-nitrobenzaldehyde. The extraction solutions were dehydrated with sodium chloride and salted out. The acetonitrile layer was purified with n-hexane and concentrated to near dryness. The residues were dissolved in 1.0 mL methanol. Then, the solutions were purified by dispersive solid phase extraction with C18, N-(n-propyl)ethylenediamine (PSA) and amino bonded silica gel (NH2) sorbents. The residues were separated on a ZORBAX C18 chromatographic column (50 mm×2.1 mm, 1.8 μm). The MS data were acquired in positive and negative multiple reaction monitoring (MRM) modes, and quantitated by the isotope internal standard method. With this approach, the linear relationships of the 28 veterinary drugs were good. The linear correlation coefficients were greater than 0.99. The limits of detection and limits of quantification were in the range of 0.1-0.8 μg/kg and 0.3-2.7 μg/kg, respectively. The average recoveries at three spiked levels (1, 5, and 20 fold of the LOQs) were 70.0%-120% with relative standard deviations of 0.9%-10.0%. The method is simple, rapid, accurate and sensitive, and it is suitable for the rapid determination of various prohibited and restricted drugs in fish and shrimp.