The method for determination of aflatoxin precursors in milk

The procedure is described for parallel determination of two aflatoxin precursors-sterigmatocystin (STC) and O-methylsterigmatocystin (OMSTC) in milk. The mycotoxins were extracted with chloroform from skimmed milk. The extract was purified with gel permeation chromatography and extract components were separated using two dimensional thin-layer chromatography on silica gel. Fluorescent densitometry was used for the quantitative measurement of toxin levels. The detection limit of the method was 1 μg/kg and the average recoveries were 81±2% and 67±4% for STC and OMSTC respectively at the contamination levels of 3 μg/kg, 2 μg/kg and 1 μg/kg.