Methods for Detection and Quantitation of Fumonisins in Corn, Cereal Products and Animal Excreta

Abstract

Fumonisins are a group of naturally occurring mycotoxins produced by strains of several different mating populations of Gibberella fujikori ( Fusarium section Liseola ). Fumonisins have been shown experimentally to be the causative agent of equine leukoencephalomalacia (ELEM), porcine pulmonary edema (PPE) syndrome, and to produce liver cancer in rats. Epidemiological evidence also indicates a possible correlation between the fumonisins and human esophageal cancer. The analytical method of choice for most samples has been high performance liquid chromatography (HPLC) using fluorescence detection. The present work describes the baseline resolution using an isocratic mobile phase of the o-phthalaldehyde (OPA) derivatives of fumonisin B₁ (FB₁), fumonisin B₂ (FB₂) and fumonisin B₃ (FB₃). The separation of the hydrolyzed forms of FB₁, partially hydrolyzed FB₁ (PHFB₁) and fully hydrolyzed FB₁ (HFB₁) is also described. Results of analyses of com from 1992 crop year in both Iowa (mean = 0.05 μg/g, N = 80) and Pennsylvania (mean = 0.37 μg/g, N = 91) were significantly lower than mean levels reported for 1988, 1989, 1990 and 1991. Significant levels of FB₁ were found in commercially prepared rat (2 μg/g) and horse (37 μg/g) feed. Levels of FB₁, (0.05 to 1.2 μg/g) found in corn meal purchased from local groceries indicated a possible source of low level exposure of humans to fumonisins. The simultaneous isocratic separation of FB₁, FB₂, FB₃ and the hydrolysis products of FB₁, PHFB₁ and HFB₁from fecal samples indicated a possible difference in metabolism of FB₁ in ruminants and nonruminants. In ruminants, the hydrolyzed forms of FB₁ composed a significant (60 to 90%) portion of the total FB₁ concentration found in the feces. In nonruminants, the parent compound, FB₁, was the dominant (90%) species present. Both ruminants and nonruminants showed limited excretion of FB₁ in their urine (<1 to 7% total FB₁ in excreta).

Keywords: Fumonisins; cereal products; corn; detection; methods.