Confirmatory test for aflatoxin M1 on a thin layer plate.

The identity of aflatoxin M1 can easily be confirmed directly on a thin layer plate by reacting aflatoxin M1 with trifluoroacetic acid (TFA). This confirmation reaction is carried out on the thin layer plate which has been developed in 2 dimensions and used for the quantitation of aflatoxin M1 in the sample. TFA is superimposed on the separated M1 spot. The plate is kept in the dark 3 min, heated to 75 degrees C for 5 min, and developed with chloroform-methanol-acetic acid-water (92 + 8 + 2 + 0.8). The Rf value of the blue-fluorescent derivative is compared with that for the M1 standard. The method was used successfully on extracts of milk, cheese, and liver. M1 quantities on the plate as low as 0.5 ng can be confirmed by this method. The method is also suitable for simultaneous confirmation of aflatoxin B1.