Evaluation of Fumonitest Immunoaffinity Columns

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Abstract
A method for the determination of fumonisins B1 and B2 in corn was developed. The method involves sample extraction with methanol:water (80:20) and the use of a commercially available Fumonitest column for sample cleanup. The capacity, selectivity, column-to-column and lot-to-lot reproducibility of the Fumonitest columns were evaluated. The total capacity of the column was found to be 1.2 μg fumonisin. Both fumonisins B1 and B2 had an equal affinity toward the Fumonitest column, with the sample matrix demonstrating little effect on the column performance. The maximum sample size was 0.5 g for samples containing total fumonisins of less than 2 ppm. After elution from the immunoaffinity column, fumonisins B1 and B2 were reacted with naphthalene-2, 3-dicarboxaldehyde (NDA) to produce a highly fluorescent derivative, 1-cyano-2-alkyl-benz[f]isoindole (CBI). The derivatives were then separated from the sample matrix on a reverse phase C-18 column with a mobile phase consisting 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 detection limit for B1 and B2 was estimated to be 10 and 4 ppb, respectively. The coefficient of variations for fumonisins B1 and B2 were determined to be 10.2% and 10.6%, respectively.