Liquid chromatographic determination and stability of the Fusarium mycotoxin moniliformin in cereal grains

Moniliformin is a mycotoxin produced by Fusarium subglutinans and other Fusarium species. A rapid, liquid chromatographic method for its determination in corn and wheat is described. Samples are extracted in acetonitrile-water (95 + 5); following defatting with n-hexane, an aliquot of the extract is evaporated and cleaned up on small C18 and neutral alumina columns successively. Reverse-phase liquid chromatography (LC) is conducted on a C18 column with 10 or 15% methanol or acetonitrile in aqueous ion-pair reagent as mobile phase, with detection by ultraviolet absorption at 229 and 254 nm. Average recoveries of moniliformin (potassium salt) added to ground corn and wheat at levels of 0.05-1.0 micrograms/g were 80% (n = 20) and 85% (n = 12), respectively, and the limit of detection was ca 0.01-0.18 micrograms/g, depending on LC conditions. Analysis of 24 samples of wheat, 4 samples of rye, and 12 samples of corn showed moniliformin in only 2 corn samples (0.06 and 0.2 micrograms/g). Moniliformin was also detected in a sample of artificially damaged (slashed) corn (0.2 micrograms/g) and selected kernels of corn that were field-inoculated with F. subglutinans and F. moniliforme (50 micrograms/g and 0.5 micrograms/g, respectively). In stability studies, moniliformin (potassium salt, 1 microgram/g) in ground corn and ground wheat heated at 50, 100, and 150 degrees C for 0.5-2 h decomposed moderately, e.g., 55% remained in corn after 0.5 h at 100 degrees C.