A survey of the occurrence of aflatoxin B1 in peanut butters by enzyme-linked immunosorbent assay.

A survey was carried out in 1986 for the occurrence of aflatoxin B1 in peanut butters (129 samples) obtained from specialist Health Food outlets. The results showed that 6.2% of the samples exceeded 10 micrograms/kg of aflatoxin, 8% contained between 2.5 and 10 micrograms/kg, and in the remainder (86%) aflatoxin could not be detected at a limit of 2.5 micrograms/kg. These results show a lower contamination by aflatoxin than found in these products in previous surveys (1982-1984). An aflatoxin B1-specific enzyme-linked immunosorbent assay (ELISA) was employed for the first time in these analyses; and to make an assessment of its performance positive aflatoxin results, together with a random selection of those below the ELISA limit of detection, were additionally analysed by conventional extraction and clean-up followed by HPLC. The ELISA technique offered a significant improvement in speed of analysis over conventional approaches, enabling a six-fold increase in sample throughput compared to that required for conventional analysis, together with other advantages.