APPLICATION OF IMMUNOAFFINITY COLUMNS TO MYCOTOXIN ANALYSIS

Immunoaffinity columns (IACs) are widely used for cleanup and isolatio n of mycotoxins extracted from foods and biological fluids, particular ly aflatoxins, ochratoxin A, and fumonisins, The columns are prepared by binding antibodies specific for a given mycotoxin to a specially ac tivated solid-phase support and packing the support suspended in aqueo us buffer solution into a cartridge, The mycotoxin in the extract or f luid binds to the antibody, impurities are removed with water or aqueo us solution, and then the mycotoxin is desorbed with a miscible solven t such as methanol, Further separation can be performed with IAC, foll owed by liquid chromatographic (LC) quantitation, either off-line or o n-line in an automated system, or by fluorometry, IACs have been used by laboratories that developed the antibodies but are also available c ommercially for aflatoxins, ochratoxin A, fumonisins, zearalenone, and deoxynivalenol. Among commercial IACs, Aflatest P is used as the clea nup step in an LC method and in a solution fluorometry method for corn , peanuts, and peanut butter that was adopted as an AOAC INTERNATIONAL Official Method after evaluation by an international collaborative st udy, As part of a fluorometer-based test kit, aflatest P was further c ertified by the AOAC Research Institute to measure total aflatoxins in 10 grains and grain products. IACs can concentrate the analyte from a large amount of sample, allowing detection limits at low parts-per-tr illion levels in some cases (e.g., for aflatoxin M-1 and ochratoxin A in liquid food matrixes), Regeneration of IACs for reuse in aflatoxin, ochratoxin A, fumonisin, and zearalenone analyses has been investigat ed.