COMPARISON OF THIN-LAYER CHROMATOGRAPHY AND COMPETITIVE IMMUNOASSAY METHODS FOR DETECTING FUMONISIN ON MAIZE

The fumonisin mycotoxins are secondary metabolites of Fusarium monilif orme, which are common worldwide in maize. Thin-layer chromatography ( TLC) and competitive indirect immunoassay (CI-ELISA) methods were comp ared for detection of fumonisin B-1 in maize. Corn from the 1991 Misso uri maize variety trials (322 samples) was collected, milled, subsampl ed, and analyzed independently by two laboratories using different scr eening methods. Fifty-two percent of the samples tested negative for f umonisin B-1 at 1 ppm by both methods. By TLC, an additional 14% of th e samples had less than 1 ppm of fumonisin B-1 and more than 1 ppm by CI-ELISA. TLC found 34% of the samples were from 1 to 10 ppm and only 1% of the samples were above 10 ppm of fumonisin B-1. CI-ELISA found 2 8% of the samples contained fumonisin levels between 1 and 10 ppm and 20% had greater than 10 ppm of fumonisin. In the remaining samples, CI -ELISA consistently reported higher fumonisin levels than TLC (160/322 ), while TLC was higher in only 10 of 322 samples. The discrepancy may be due to fumonisin B-1 alone being detected by TLC, while CI-ELISA m easures total fumonisins. Both methods are well suited for rapid scree ning of maize samples for fumonisin contamination.