USE OF IMMUNOAFFINITY CHROMATOGRAPHY AS A PURIFICATION STEP FOR THE DETERMINATION OF AFFATOXIN M(1) IN CHEESES

A method using immunoaffinity as a purification step for the determina tion of aflatoxin M(1) in cheese is described. A simple solvent extrac tion with dichloromethane followed by a washing step with N-hexane giv es a prepurified extract. A comparison between two ways of aflatoxin M (1) purification, by solid-phase extraction clean-up and by immunoaffi nity, was carried out. The use of immunoaffinity columns containing mo noclonal antibodies against aflatoxin M(1) gives the best result, i.e. a very clean preparation containing purified aflatoxin M(1). The quan tification of aflatoxin M(1) is then performed by high performance liq uid chromatography using fluorometric detection. This method was succe ssfully carried out on naturally-contaminated and spiked cheeses. Reco veries are about 75%. The limit of quantification is 0.020 mu g of afl atoxin M(1) per kg of cheese. This method seems suitable for use in mo nitoring programmes for aflatoxin M(1) contamination in dairy products such as cheese.