Enzyme-linked immunosorbent (ELISA) determination of aflatoxin B1 in peanut butter: collaborative trial.

Fourteen laboratories in the United Kingdom participated in a collaborative trial of a commercially available ELISA test kit for the determination of aflatoxin B1 in peanut butter. Each laboratory carried out six replicate analyses of each of six individual samples. Collaborators received a control, uncontaminated sample, together with samples prepared by blending naturally-contaminated and control material to give target levels of 8 micrograms/kg, 25 micrograms/kg and 75 micrograms/kg. Two of these samples (8 micrograms/kg and 25 micrograms/kg) were supplied as undisclosed duplicates. The repeatabilities of the assay ranged from 6.2 to 16.7 micrograms/kg. The reproducibilities for aflatoxin B1 concentrations in naturally-contaminated samples ranged from 3.6 to 18.7 micrograms/kg using uncontaminated peanut butter as a reference blank. Modifications to the format of the commercial kit were recommended as a result of the collaborative trial.