IMMUNOAFFINITY COLUMN COUPLED WITH LIQUID-CHROMATOGRAPHY FOR DETERMINATION OF FUMONISIN B-1 IN CANNED AND FROZEN SWEET CORN

A modified liquid chromatographic (LC) method for determining fumonisi n B-1 (FB1) in corn was applied to canned and frozen sweet corn. The c orn is extracted with methanol-water (8 + 2), and the extract is filte red. The filtrate is diluted with water and passed through an immunoaf finity column. After the column is washed with water, FB1 is eluted wi th methanol-water (8 + 2). The eluate is evaporated to dryness by usin g a vacuum concentrator, and the residue is dissolved in acetonitrile- water (1 + 1). FB1 is derivatized with o-phthaldialdehyde. The derivat ive is separated on a reversed-phase C-18 LC column using acetonitrile -water-acetic acid (50 + 50 + 1) and quantitated with a fluorescence d etector. Recoveries of FB1 from canned and frozen corn spiked over the range of 50-200 ng/g were 76-88%. The limit of determination was abou t 25 ng/g, and the limit of detection was about 4 ng/g. The method was applied to 97 commercial canned and frozen sweet corn samples collect ed from different areas of the United States. Sixty samples contained no FB1. Low levels (trace-82 ng FB1/g corn) were found in 35 samples; 235 ng FB1/g was found in 1 canned corn sample, and 350 ng FB1/g was f ound in 1 frozen corn sample.