A method using immunoaffinity as a purification step for the determination of aflatoxin M1 in cheese is described. A simple solvent extraction with dichloromethane followed by a washing step with N-hexane gives a prepurified extract. A comparison between two ways of aflatoxin M1 purification, by solid-phase extraction clean-up and by immunoaffinity, was carried out. The use of immunoaffinity columns containing monoclonal antibodies against aflatoxin M1 gives the best result, i.e. a very clean preparation containing purified aflatoxin M1. The quantification of aflatoxin M1 is then performed by high performance liquid chromatography using fluorometric detection. This method was successfully carried out on naturally-contaminated and spiked cheeses. Recoveries are about 75%. The limit of quantification is 0.020 microgram of aflatoxin M1 per kg of cheese. This method seems suitable for use in monitoring programmes for aflatoxin M1 contamination in dairy products such as cheese.

Patulin is immunosuppressive and there is limited evidence of its carcinogenicity in experimental animals. The International Agency for Research on Cancer (IARC) initiated a programme for the development of degradation techniques for the commonly investigated mycotoxins. As a part of this programme, the following techniques were tested for the degradation of patulin: treatment with ammonia, treatment with ascorbic acid, and treatment with potassium permanganate in acidic or in alkaline conditions. Patulin analysis was performed by using HPLC with UV detection. Mutagenic activity of degradation residues was tested by in Salmonella typhimurium strains TA 97a, TA 98, TA 100, and TA 102. Complete disappearance of patulin was not achieved after 92 h of treatment with ascorbic acid. All the other methods tested led to complete removal of the molecule. However, the technique using potassium permanganate in acidic conditions produced residues which were mutagenic without activation to Salmonella typhimurium strains TA 100 and TA 102, which was attributed later to Mn2+. The two other techniques gave satisfactory results and were selected for further validation studies.

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