Radioimmunoassay of ochratoxin A in barley

A simple and rapid radioimmunoassay was developed for the quantitative determination of ochratoxin A in barley. [14C]ochratoxin A, with a specific activity of 130 Ci/mol, was used as the tracer. Toxin levels below 100 ng/ml required a cleanup step. Three methods (the Association of Official Analytical Chemists cleanup method, the solvent partition method, and the Extrelut 3 column cleanup method) were compared.