Quantitative Determination of Four Nitrofurans and Corresponding Metabolites in the Fish Muscle by Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry

A method validated based on the European Union (EU) regulations for determining the presence of furazolidone, furaltadone, nitrofurazone, nitrofurantoin and their corresponding metabolites AOZ, AMOZ, SC and A H in fish muscle was developed. Samples were acid-hydrolyzed, treated with 2-nitrobenzaldehyde and extracted with ethyl acetate. The extracts were dried in a N-2 stream and redissolved in methanol:water (50:50, v/v). Analysis was performed by LC/ESI/MS/MS. This developed method carried limits of quantification lower than 10 mu g/kg for the nitrofurans and 1.0 mu g/kg for the metabolites. It was observed that the decision limit (CC alpha) ranged from 2.93 to 5.01 mu g/kg for the nitrofurans and 0.19 to 0.43 mu g/kg for the metabolites. The detection capability (CC beta) was between 3.62 and 6.20 mu g/kg for the nitrofurans and between 0.23 and 0.54 mu g/kg for the metabolites. The linear calibration curve parameters in the fortified fish muscle were between 1.0-100.0 mu g/kg and 0.1-10.0 mu g/kg for the nitrofurans and metabolites, respectively.