AUTOMATED AFFINITY LIQUID-CHROMATOGRAPHY SYSTEM FOR ONLINE ISOLATION, SEPARATION, AND QUANTITATION OF AFLATOXINS IN METHANOL-WATER EXTRACTS OF CORN OR PEANUTS

An automated liquid chromatography (LC) procedure has been developed for the determination of aflatoxins in corn and peanuts. The automated LC system consists of the following: two pumps, an autosampler, an isolation column (immunoaffinity or methacrylate copolymer), an automated switching valve, a C18 column, an electrochemical cell, a fluorescence detector, and a data system. Filtered methanol: water (75:25) extracts of the test portions are injected into the LC system. With the switch in position 1, water is pumped through the autosampler and isolation column and then discarded. With the switch in position 2, the mobile phase consisting of methanol:acetonitrile:water (26:18:56), 1 mM KBr, and 1 mM HNO3 is pumped through the isolation column, C18 column, electrochemical cell, and detector. Aflatoxins B1 and G1 react with electrochemically generated bromine to form fluorescent derivatives. Both isolation columns can be used for >50 injections. Recovery of aflatoxins from both commodities spiked at 5-30 ng/g was about 85%.