Simultaneous HPLC determination of aflatoxins B1, B2, G1 and G2 in Tunisian sorghum and pistachios

A rapid and sensitive reversed-phase high-performance liquid chromatographic method has been used for the determination of aflatoxins (AFs) B1, B2, G1 and G2 in Tunisian sorghum and pistachios. Samples were extracted with methanol/water solution and cleaned by immunoaffinity column. HPLC separation was performed on a C18 Spherisorb analytical column with a mobile phase consisting of water:methanol:acetonitri1e (60:20:20, v/v/v). The method proved to be rapid, selective and reproducible. In-house performance characteristics were established; calibration curves were linear from 0.12 to 8 ng/g for AFs B1 and G1 and from 0.06 to 4 ng/g for AFs B2 and G2. Quantification limits were found to be significantly lower than Tunisian and European aflatoxin regulatory limits. They were 0.16 ng/g for AFB1 and 0.08 ng/g for AFs B2, G1 and G2. Aflatoxin recoveries in sorghum and pistachios samples spiked at 0.5 and 2 ng/g varied from 68.3 to 87.7%. AFs were detected and quantified in investigated commodities. The incidences were 52.5 and 62%, respectively, for pistachios and sorghum samples, with respective average contamination levels of 21.8 ± 38.0 and 9.9 ± 11.5 ng/g.