LIQUID-CHROMATOGRAPHIC DETERMINATION OF AFLATOXIN M(1) IN MILK POWDERUSING IMMUNOAFFINITY COLUMNS FOR CLEANUP - INTERLABORATORY STUDY

A liquid chromatographic method for determining low aflatoxin M1 conce ntrations in milk was evaluated in an International Dairy Federation ( IDF) interlaboratory study. The study involved 16 participants from 11 countries. The method, chosen after a comparison of several methods b y a preparatory group, uses an immunoaffinity column for cleanup. As t he sample passes through the column, antibodies selectively bind with aflatoxin M1 (antigen) present and form an antibody-antigen complex. A ll other components of the sample matrix are washed off the column wit h water. Then, aflatoxin M1 is eluted from the column with acetonitril e, which is collected. Final determination is carried out by reversed- phase liquid chromatography with fluorescence detection. Over the test ed range (80-600 ng aflatoxin M1/kg milk powder), an RSDR ranging from 11 to 23% was obtained by analyzing 24 samples (blind duplicates), 2 samples of which were blanks.