Combining ultrasound‐assisted extraction and vortex‐assisted liquid–liquid microextraction for the sensitive assessment of aflatoxins in aquaculture fish species

Although aflatoxins contamination in feedstuff is a well‐known problem, and hence these residues are controlled in poultry products, there is scarce information regarding the presence of these toxic substances in aquaculture fish, facilities that use several feedstuff for fish breeding. A simple, rapid, and sensitive method has been therefore developed for aflatoxins (B1, B2, G1, and G2) assessment in aquaculture products by combining ultrasound probe‐assisted extraction and vortex‐assisted liquid–liquid microextraction as a sample pretreatment, and high‐performance liquid chromatography‐tandem mass spectrometry as a separation/detection system. Aflatoxins were extracted from fish flesh/liver with a 60:40 acetonitrile/aqueous phosphate buffer (pH 7.0) mixture before preconcentration and clean‐up by vortex‐assisted liquid–liquid microextraction under the following optimized conditions: 5.0 mL of fish extract at pH 7.0 and NaCl at 0.5% (w/v), 400 μL of chloroform as extracting solvent, and vortex shaking at 2000 rpm for 1 min. The proposed method is shown to be precise and accurate, and the limit of quantitations (from 0.20 to 1.10 μg kg^?1) were lower than the value established by the European Commission Regulation for aflatoxins in foodstuff. Results have shown that fish flesh is free of aflatoxins, but aflatoxins B2 and G1 were quantified in fish liver.