EVALUATION OF FUMONITEST IMMUNOAFFINITY COLUMNS

A method for the determination of fumonisins B1 and B2 in corn was dev eloped. The method involves sample extraction with methanol:water (80: 20) and the use of a commercially available Fumonitest column for samp le cleanup, The capacity, selectivity, column-to-column and lot-to-lot reproducibility of the Fumonitest columns were evaluated. The total c apacity of the column was found to be 1.2 mu g fumonisin. Both fumonis ins B1 and B2 had an equal affinity toward the Fumonitest column, with the sample matrix demonstrating little effect on the column performan ce. The maximum sample size was 0.5 g for samples containing total fum onisins of less than 2 ppm. After elution from the immunoaffinity colu mn, fumonisins B1 and B2 were reacted with naphthalene-2,3-dicarboxald ehyde (NDA) to produce a highly fluorescent derivative, 1-cyano-2-alky l-benz[f]isoindole (CBI). The derivatives were then separated from the sample matrix on a reverse phase C-18 column with a mobile phase cons isting of acetonitrile:water:acetic acid (55:45:1) Average recoveries of fumonisins B1 and B2 from corn samples spiked at a level of 1000 ng (500ng B1 + 500ng B2)/g were 85.4 and 87.1%, respectively. The detect ion limit for B1 and B2 was estimated to be 10 and 4 ppb, respectively . The coefficient of variations for fumonisins B1 and B2 were determin ed to be 10.2% and 10.6%, respectively.