[Determination of nitrofuran metabolites residues in animal tissues by LC-MS/MS method].

A LC-MS-MS method is presented to analyze simultaneously the metabolites of four nitrofuran veterinary drugs in animal muscle tissue e.g., furazolidone, furaltadone, nitofurantoina and nitrofurazone. The sample clean up were performed by a liquid-liquid extraction with ethyl acetate, after a hydrolysis and derivatization with 2-nitrobenzaldehyde. Nitrofurane metabolites were determined by LC-ESI-MS/MS in positive mode. The LC was equipped with column Luna C18 Phenomenex. A binary gradient mobile phase was used as methanol solvent B containing 0.5 mM ammonium acetate and methanol (80:20 v/v). The method was validated according to criteria of Decision Commission No 2002/657/EC. Samples were fortified with metabolites of nitrofuran between 0.5-2.0 microg/kg with AOZ-d4, and AMOZ-d5 as internal standard. The mean recoveries from meat spiked at 1.0 microg/kg were 84.5-109.7%. Limit of decision (CCalpha) was between 0.25-0.57 and capability of detection (CCbeta) 0.32-0.77 microg/kg.