Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/20/2000
Publication Date: N/A
Citation: Interpretive Summary: Fumonisins are fungal toxins produced by several species of Fusarium molds. Recently the U.S. Food and Drug Administration has established guidance levels for these mycotoxins in foods and feeds. This manuscript describes the development of a rapid test for the fumonisins in maize. The technique, fluorescence polarization immunoassay, has significant promise as a low cost, rapid, alternative to enzyme linked immunosorbent assays (ELISAs) and has certain advantages over the ELISA methods, particularly when the analyses must be done rapidly in a serial fashion, such as at grain elevators.
Technical Abstract: Fumonisins, mycotoxins produced by certain species of Fusaria, are commonly found worldwide as contaminants in maize. We report the development of a rapid, portable fluorescence polarization-based assay for fumonisins in maize. The assay was based on the competition of unlabeled fumonisin, from a sample, with a fluorescently tagged fumonisin (FB1-FL) for a fumonisin-specific monoclonal antibody in solution. The fluorescence polarization (FP) of the tagged fumonisin was increased upon binding with the antibody. In the presence of free toxin less of the FB1-FL was bound and the polarization signal was decreased. The assays were very simple to perform, requiring only mixing of an aqueous extract of maize with the tagged fumonisin and antibody, and required less than 2 minutes per sample, excluding extraction time. Two permutations of the assay were tested, one with each sample matrix serving as it's own blank, and the other with all of the samples compared relative to a PBS blank with normalization of the data similar to an ELISA. The limit of detection, defined as the toxin content associated with a fluorescence polarization signal five standard deviations from that of a fumonisin-free control, was 0.5 ug FB1/g in spiked maize. Recoveries from spiked maize over the range of 0.5 to 20 ppm averaged 94.3% +/- 13.8%. Forty eight samples of field-contaminated maize were tested by the FP and an established HPLC method, with a good correlation between the two (r2=0.85 to 0.88). For these samples, the two variations of the FP assay also compared well to one another (r2=0.97), suggesting the assay principle is very robust.