Development and Evaluation of a Minicolumn Assay for the Detection of Aflatoxin M₁ in Milk

¹ College of Veterinary Medicine, Faculty of Toxicology, Texas A&M University, College Station 77843

A practical field method for the chemiselective immobilization and detection of aflatoxin M₁ in milk has been developed and is being marketed. In this new method, aflatoxin M₁ is selectively adsorbed at the interface of a layer of neutral sand and a band of magnesium silicate (Florisil) packed in a glass minicolumn. Aflatoxin M₁, at .5 ppb in contaminated milk, can be easily visualized as a band of bright blue fluorescence. Briefly, raw or homogenized and pasteurized milk is diluted with water (1:1, vol/vol) and passed through a C₁₈ cartridge. Aflatoxin M₁ is then partitioned by polarity, eluted with acetone-methylene chloride, and added to the minicolumn. The minicolumn is washed and viewed under long wave UV light. The limit of detection for this assay was .2 ppb, which was similar to the .3 ppb obtained using an immunoaffinity column, followed by minicolumn detection. The assay was accurate, rapid, easy to perform, and stable.

Key Words: aflatoxin M₁ • milk detection • minicolumn assay

Submitted on June 1, 1993
Accepted on December 13, 1993