Quantitative determination of ochratoxin A in vegetable foods

A simple method for the quantitative determination of ochratoxin A (OA) in rice and other vegetable foods (oatmeal, coconut flakes and peas) is described. This procedure implies an acetonitrile-4% KCl -6N HCl (88+10+2) extraction of the acidic OA, subsequent twodimensional thin-layer chromatography (TLC) and detection by fluorescence after exposure to ammonia fumes (excitation at 340 nm; emission at 475 nm). The quantitative detection limit for OA in rice or coconut flakes is 2.4–4 μg/kg and the recovery is 96%. For oatmeal and peas the detection limit is only 20 μg/kg because of the interference by other metabolites.