Aflatoxins in nuts assayed by immunological methods

Different kinds of raw and processed nuts available in the local retail market were investigated for aflatoxin content. Total aflatoxins and aflatoxin B-1 content were determined by immunoaffinity chromatography with fluorescence detection after reaction with bromine solution and by immunoenzymatic test kits. Of 29 investigated samples, 38% were contaminated. The total aflatoxin content in contaminated samples was between 1.20 mu g/kg for peanuts and 5.50 mu g/kg for walnuts. The concentration of aflatoxin B1 found in contaminated samples was between 0.35 mu g/kg for cashew nuts and 4.04 mu g/kg for walnuts. The mean recovery of total aflatoxins was 95% for the Ridascreen test and 92% for immunoaffinity chromatography with fluorescence detection. For aflatoxin B-1 the mean recovery was 84%.