Extraction, cleanup, and quantitative determination of aflatoxins in corn

A method is proposed for extraction and cleanup of corn samples for the quantitation of 4 aflatoxins by high pressure liquid chromatography (HPLC). After aqueous methanol extraction, ammonium sulfate treatment, and partition of aflatoxins into chloroform, sample extracts are partially purified on Sep-Pak cartridges or small columns packed with HPLC grade silica; cleanup requires only 13 mL solvent/sample. Aflatoxins B1, B2, G1, and G2 in the purified extract are resolved in ca 10 min by normal phase HPLC on a microparticulate (5 mum) silica gel column with a 50% water-saturated chloroform-cyclohexane-acetonitrile-ethanol solvent, and are measured by ultraviolet fluorescence in a silica gel-packed flowcell. Recoveries of added aflatoxins B1, B2, G1, and G2 were 84-118% at levels of 1.5-125 micrograms/kg.