Determination of nitrofuran metabolites in shrimp by high performance liquid chromatography with fluorescence detection and liquid chromatography–tandem mass spectrometry using a new derivatization reagent

A high performance liquid chromatography with fluorescence detection (HPLC–FLD) method for the simultaneous determination of total nitrofuran metabolite residues (furazolidone, furaltadone, nitrofurantoin, and nitrofurazone) in shrimp was developed. The method involves the acid hydrolysis of protein-bound metabolites, followed by the derivatization of the freed metabolites with the new fluorescent derivatization reagent 2-hydroxy-1-naphthaldehyde (HN) and subsequent liquid–liquid extraction (LLE). Separation is achieved on a YMC-Pack Polymer C18 column under alkaline conditions, and the high fluorescence intensity of the derivatives at an emission wavelength Em = 463 nm (Ex = 395 nm) enables, for the first time, their simultaneous determination in shrimp at concentrations as low as 1 μg/kg by HPLC–FLD. The method was validated using blank shrimp fortified with all four metabolites at 0.5, 1.0 and 2.0 μg/kg. Recoveries were >87% with relative standard deviations of <8.1% for all four metabolites. Furthermore, the results obtained by HPLC–FLD were in very good agreement with those obtained by LC–MS/MS analysis.