High pressure liquid chromatographic determination and fluorescence detection of aflatoxins in corn and dairy feeds

A high pressure liquid chromatographic (HPLC) method is described for the determination of aflatoxins B1, B2, G1, and G2 in animal feeds at levels as low as 2.5 ppb. Samples are extracted with acetonitrile-water and initially purified by using a Sep-Pak silica cartridge. The aflatoxins are then reacted with trifluoracetic acid and acetonitrile-water (1 + 1). After filtration, the aflatoxins are completely resolved on a 10 micrometer C18 column using a radial compression separation system with an acetonitrile-water solvent system. Aflatoxins G2a, B2a, G2, and B2 were reported in less than 30 min, using fluorescence detection. The method was successfully applied to samples at levels of 20-2.5 ppb added aflatoxins with recoveries in the range of 82-99%.