Methods for determining ochratoxin A and other nephrotoxic mycotoxins

Chemical assays are of major importance for the determination of mycotoxins. Generally, all chemical methods for the analysis of mycotoxins include the basic steps of extraction, clean-up, separation, detection, quantification and confirmation of identity. The various approaches that exist for the determination of nephrotoxic mycotoxins, and in particular the ochratoxins, are discussed below. In conventional procedures, clean-up is usually achieved by liquid-liquid extraction or adsorption column chromatography, followed by thin-layer chromatography or high-performance liquid chromatography and ultraviolet or fluorescence detection. The recent introduction of methods based on immunochemical principles has had a large impact on analytical methodology for mycotoxins, including the ochratoxins, in both the purification and determination steps. The enzyme-linked immunosorbent assay approach for screening and (semi-)quantitative determination and the immunoaffinity column approach for rapid clean-up followed by conventional instrumental analysis are rapidly gaining ground. These techniques also offer possibilities for automated systems. To assist analysts in improving their data in mycotoxin research, the Community Bureau of Reference of the European Commission has produced several reference materials for mycotoxins; others, such as a reference material for ochratoxin A in grains, are in development.