Liquid chromatography coupled to high-resolution-Orbitrap mass spectrometry for the determination of nitrofuran metabolites in fish samples

Nitrofurans (NFs) are synthetic antibiotic drugs employed for the treatment of bacterial diseases in livestock production or as food additives in industrial farming of food-producing animals. The most widely used NFs in veterinary medicine are nitrofurantoin (NFT), furazolidone (FZD), nitrofurazone (NFZ) and furaltadone (FTD). After intake, NFs are extensively metabolized into their corresponding metabolites (NFMs), identified as 1-amino-hydantoin (AHD), 3-amino-2-oxazolidone (AOZ), semicarbazide (SEM) and 3-amino-5-methyl-morpholino-2-oxazolidinone (AMOZ), for nitrofurantoin, furazolidone, nitrofurazone and furaltadone, respectively. NFs and their metabolites are suspected to possess carcinogenic and mutagenic potency, therefore their application in food and animal production was banned in the EU in 1995 and in the USA in 2002. Since parent NFs are extensively metabolized to tissue-bond metabolites, recent analytical methods have been focused on the determination of the NFMs instead of the parent compounds. In the present study a modified extraction technique including at first a hydrolysis-derivatization step [1] was validated and applied for the simultaneous determination of four of NFMs residues (AHD, AOZ, SEM, AMOZ) in fish samples from aquacultures located in North Western Greece.