Derivatization procedure for identification of aflatoxin M1 on a thin layer chromatogram

A commodity extract containing presumptive aflatoxin M1 is placed on an origin spot of a thin layer chromatographic plate and overspotted with trifluoroacetic acid. The mixture is held in the dark 30 min at ambient temperature and then 30 min at 55 degrees C. The plate is developed with CHCL3-acetone-2-propanol (85+10+7). The Rf values of reacted and unreacted aflatoxin M1 are compared with authentic M1 similarly treated for identification. The lowest concentration that has been identified is 0.1 mug/kg.