Abstract: A method was developed for the simultaneous determination of aflatoxins (AFs) (B1, B2, G1 and G2), zearalenone (ZEA) and ochratoxin A (OTA) in cereal grains by high performance liquid chromatography （HPLC） with fluorescence detection after immunoaffinity column clean-up and post-column derivatization. Cereal grain sample was extracted with methanol-water (80∶20, v/v). The extract was purified by immunoaffinity column and the toxins were separated by reversed-phase HPLC, and quantified with fluorescence detection after photochemical derivatization. The separation was performed on a Nova-Pak column (3.9 mm i.d.×150 mm, 4 μm, Waters) with a linear gradient of methanol-acetonitrile-1%phosphoric acid mixture. The calibration curves for mycotoxins were made in the concentration range of 0.24-6.0 for AFs (B1,B2,G1 and G2), 4.0-100.0 for ZEA and 0.5-40.0 μg/L for OTA. Recoveries of the different cereal grains (wheat, rice, rye) spiked with mycotoxins at levels ranged from 0.24-1.0 μg/kg for AFs (B1, B2, G1 and G2), 4.0-16.0 μg/kg for ZEA and 0.5-3.0 μg/kg for OTA were from 70.8% to 94.0% and relative standard deviations were between 2.79% and 9.38%. The limits of detection were 0.24 μg/kg for AFs (B1, B2, G1 and G2), 0.5 μg/kg for OTA and 4.0 μg/kg for ZEA.

Key words: cereal grain
, high performance liquid chromatography (HPLC), mycotoxin, photochemical derivatization, immunoaffinity column