Isolation and Determination of Aflatoxin B1 in Cottonseed Meals

Abstract

Abstract A method for the isolation and determination of aflatoxins in commercial samples of cottonseed meal has been devised. Meal samples were defatted with hexane and the aflatoxins removed from the meal by acetone extraction. The pigments and residual lipids were removed from the acetone by nitration of the cold solution. The anatoxin was further isolated by evaporating the acetone and redissolving the residue in hot methanol. After cooling, the insolubles were discarded and the methanol-soluble materials taken up in chloroform. The chloroform solution was spotted on silicic acid thin layer chromatographic plates along with suitable anatoxin standards. After development with 9:1 (v/v) chloroform :acetone, the chromatographic plates were examined under ultraviolet light. Four of the eight cottonseed meals examined contained fluorescent material chromatographically similar to aflatoxin B1 in amounts varying from 19 to 186 parts per billion (ppb). The identity of the material in the 186 ppb sample was verified as aflatoxin by duckling bioassay. Trials using rainbow trout confirmed the chemical findings. These trout experiments will be described in detail in another report.