Improved method for confirmation of identity of aflatoxins B1 and M1 in dairy products and animal tissue extracts.

A method is described for confirming the identity of aflatoxins B1 and M1 in dairy products and liver extracts on a thin layer plate. Extracts and standards containing aflatoxins B1 and M1 are spotted on 10 x 10 cm plates, which are developed 2-dimensionally in mixtures of isopropanol-acetone-chloroform. After the first development, trifluoroacetic acid-hexane (1 + 4) is sprayed on that part of the plate containing the separated extract components and the underdeveloped standard spots of B1 and M1, and the plate is heated 6-8 min at 75 degrees C. Then the plate is developed in a second direction, and the reaction products of B1 and M1 with trifluoroacetic acid from the extract are compared with the same derivatives of the respective standards. The method has been used successfully on extracts of milk, cheese, and liver containing 0.1 ng B1 or M1/g and can be completed in 35-45 min.