ANALYSIS OF FUMONISINS SAND ALTERNARIA-ALTERNATA TOXIN BY LIQUID-CHROMATOGRAPHY ENZYME-LINKED-IMMUNOSORBENT-ASSAY

Use of a direct competitive enzyme-linked immunosorbent assay (ELISA) as a postcolumn monitoring system after liquid chromatography (LC) is described for analysis of different fumonisin analogs. Without cleanup and derivatization, sample extracts are directly injected into a Cls reversed-phase column and then subjected to LC. Fractions (0.5 mL, eac h) are collected and then analyzed by ELISA. LC using a water-methanol gradient separated the 3 major fumonisins FmB1, FmB2, and FmB3, and a s low as 0.1 ng FmB1 could be detected. Recovery of FmB1 added to grou nd corn (100-1000 ng/g) and then extracted with CH3CN-H2O (1 + 1, v/v) was 78.8%, Analysis of fumonisins in one starch and 14 naturally cont aminated corn samples showed that FmB1 was the major fumonisin. Ten sa mples also were contaminated with FmB2, but only 2 samples were contam inated with FmB3. The method also was used to analyze extracts from cu ltures of 3 Alternaria alternata (AAL) strains. Both FmB1 and the AAL toxin TA were detected in the culture extracts, and their amounts vari ed considerably with the cultures tested.