Collaborative Study of Methods for the Determination and Chemical Confirmation of Aflatoxin M1 in Dairy Products

Abstract

An international collaborative study involving 19 collaborators was conducted to test methods for the determination and chemical confirmation of aflatoxin M₁ in dairy products. For the quantitative method, collaborators assayed samples of liquid and powdered milk, cheese, and butter containing low levels of M₁. Statistical results indicated that sensitivity and precision of this method were comparable to other AOAC methods for aflatoxin M₁. Impurities were present in blue cheese extracts that tended to interfere with thin layer chromatography. Analysis of liquid milk samples from different areas revealed that some milk extracts may require column chromatography. For the chemical confirmatory method, collaborators prepared acetate and hemiacetal derivatives of M₁ in extracts of liquid milk and colby cheese. A sensitivity limit of 30 ng M₁ was apparent for the method, and most collaborators easily identified the derivatives. As a result of this collaboration, both methods have been adopted as official first action methods.