The limit of determination is approximately 50 micro-gram/kg. The method consists in extracting of a test portion with a mixture of acetonitrile and potassium chloride solution, filtrating, defatting, purifying, filtrating again, extracting into chloroform which is subsequently evaporated. Dissolution of the dry extract in a mixture of benzene and acetonitrile and thin layer chromatography. Determination by visual measurement or by measurement of the intensity of fluorescence under UV ligt by comparison with known quantities of zearalenone applied to the same plate. Confirmation using bis-diazotized benzidine reagent.