Analysis of nitrofuran metabolic residues in salt by liquid chromatography–tandem mass spectrometry

Recent reports from the Brazilian Agricultural Ministry program of residue control describe some cases of the presence of semicarbazide, the target metabolite of nitrofurazone {2-[(5-nitro-2-furanyl)methylene]-hydrazinecarboxamide}, in samples of salted chicken meat. Since that contamination can be originated from other reasons in addition to nitrofurazone abuse, our laboratory has developed a sensitive and simple method for detection of four nitrofuran metabolites in salt samples. This method include a previous hexane extraction of the metabolites followed by a derivatization reaction with 2-nitrobenzaldehyde. The nitrophenyl derivatives were analyzed by liquid chromatography–tandem mass spectrometry without any additional clean-up procedures. The limit of quantification for routine analysis was 0.5 (mu)g kg^-1 for each metabolite.