Rapid high pressure liquid chromatographic determination of aflatoxin M1 in milk and nonfat dry milk.

A modification of the current revised AOAC method, 26.A10-26.A15, is described for the rapid analysis of aflatoxin M1 in milk and nonfat dry milk. The method incorporates chloroform extraction and eliminates the need for column chromatography by using liquid-liquid partition for sample extract cleanup. Quantitation is carried out by using fluorescence detection combined with high pressure liquid chromatography (HPLC) of aflatoxin M1 which has been converted to aflatoxin M2a with trifluoroacetic acid. The method has a detection limit of 0.014 micrograms/L (2 X signal/noise) for whole milk. For 6 samples of naturally contaminated nonfat dry and freeze-dried milk, the modified method gave an average result of 0.698 micrograms/L; the AOAC method gave an average result of 0.386 micrograms/L.