Simultaneous determination of eight nitrofuran residues in shellfish and fish using ultra-high performance liquid chromatography–tandem mass spectrometry

Abstract

Illegal use of nitrofurans (NFs) in aquaculture is of great concern for food safety throughout the world. A liquid chromatography-based method coupled to tandem mass spectrometry was developed and validated for measuring levels of four conventional NFs (nitrofurantoin, furazolidone, nitrofurazone, and furaltadone) and four additional NFs (nifursol, nifuroxazide, nifurpirinol, and sodium nifurstyrenate) in shellfish and fish samples. Limits of detection and quantitation were 0.01–0.2 µg/kg and 0.04–0.5 µg/kg for seven NFs, except for sodium nifurstyrenate (2 µg/kg and 5 µg/kg). Recoveries were 91.6–107.3 % with inter-day and intra-day relative standard deviations in the range of 0.8–9.6 % and 0.7–10.7 %, which were assessed at four fortification levels. The validated method was applied to 397 shellfish and 140 fish collected from South China in 2014−2017. The total non-compliant rate (>1.0 µg/kg) of the four major NFs was 4.3 % in shellfish (<0.03–7.8 µg/kg) and 5.0 % in fish (<0.03–6.8 µg/kg), with the newly added drugs undetected in all samples. Semicarbazide was frequently detected in several kinds of shellfish at lower levels (0.1–3.1 µg/kg) as reported in shrimps, indicating potential endogenous generation or environmental contamination. We propose that this method be used to monitor NF residues in the future.