Evaluation of silica cartridge purification and hemiacetal formation for liquid chromatographic determination of aflatoxins in corn.

Rapid silica cartridge cleanup, acid-catalyzed conversion of aflatoxins B1 and G1 to hemiacetals, and reverse-phase liquid chromatography with fluorescence detection were evaluated for effectiveness in determining aflatoxins B1, B2, G1, and G2 in corn at concentrations ranging from 2 ng/g to 100 micrograms/g. In testing the method, aflatoxins applied to silica cartridges were recovered at greater than 97.1% overall. Conversion of aflatoxins B1 and G1 to their hemiacetals was shown to be complete (150 micrograms of toxin per extract). Application of these techniques to spiked corn extracts yielded data indicating excellent repeatability of derivatization relative to paired standards; coefficients of variation ranged from 1.08% to 5.81%. The repeatability of the method with naturally contaminated corn was also excellent; coefficients of variation ranged from 1.15% to 3.97%. Liquid chromatographic determination of aflatoxins in corn using fluorescence detection was sensitive, accurate, and precise resulting in applicability from less than 1 ng/g of aflatoxin B1 to greater than 100,000 ng/g.