The determination of nitroimidazole residues in fish and fish products

Abstract

A method was developed and validated for the determination of nitroimidazoles (NIs) including 2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI), ipronidazole (IPZ), 1-methyl-2-(2'-hydroxyisopropyl)-5-nitroimidazole (IPZ-OH), metronidazole (MNZ), 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole (MNZ-OH), ronidazole (RNZ) and dimetridazole (DMZ) in fish and crustaceans by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The compounds were extracted with acidic acetonitrile, followed by solid phase extraction (SPE) C18 clean up and hexane washing. The validated method has a linear range from 0-50 ng/g in target representative species (tilapia, salmon and shrimp), with LOD from 0.07 - 1.0 ng/g and LOQ from 0.21 - 3.0 ng/g, depending on the analyte. Recoveries ranged from 87 to 121% for the analytes of interest. Method precision ranged from 6 to 26% RSD with HorRat values within typical limits of acceptability. The method successfully analyzed rainbow trout samples treated with MNZ in a depletion study under controlled conditions and is suitable for use in a regulatory monitoring program for residues of nitroimidazoles in seafood and aquacultured products.