Affinity column cleanup and direct fluorescence measurement of aflatoxin M1 in raw milk

Abstract

Aflatoxin M1 is a carcinogen secreted in the milk of cows which ingest feed contaminated with aflatoxin B1 Surveillance of aflatoxin residues requires a simple, rapid, sensitive, and quantitative test. A test has been developed which uses an antibody affinity column to isolate aflatoxin M1 from raw milk. The skim portion is passed directly through the column. The column is then washed and the aflatoxin M1 eluted into a test tube. The affinity column provides sufficient sample cleanup to measure the aflatoxin level directly using a fluorometer. Using raw milk samples spiked with known amounts of aflatoxin M1, the method provides 97% recovery over the range 0.05ppb to 0.5ppb. The detection limit is 0.05ppb. Values obtained on the fluorometer agree with those obtained by HPLC. The time required to quantitate a prepared sample is about 8 minutes.