Determination of Fumonisins in Corn:  Evaluation of Competitive Immunoassay and HPLC Techniques

Abstract

The fumonisins, mycotoxins produced by Fusarium moniliforme, are known to occur as natural contaminants of corn worldwide and to be associated with several animal disease syndromes. High-performance liquid chromatography (HPLC) and monoclonal antibody-based (MAb) competitive direct enzyme-linked immunosorbent assay (CD-ELISA) methods, developed for the determination of fumonisins in corn, were compared. CD-ELISA results for naturally contaminated corn were consistently higher than corresponding HPLC results. Quantitative differences were reduced by decreasing the organic phase composition of the extract and by introducing a hexane partitioning step. The results were indicative of a possible lipid-based matrix effect, but when applied to fumonisin-free corn spiked with fumonisin levels ranging from 0.8 to 12.8 μg/g, analyses by both techniques were well correlated ( r = 0.996). It is concluded that structurally related fumonisin-like compounds, present in naturally contaminated corn, may contribute to the differences recorded between the two methods, although the MAb-based CD-ELISA may still be used as an initial semiquantitative screening technique. Keywords: Fumonisins; immunoassay; ELISA; HPLC; corn