Analysis of fumonisin B1 and its hydrolysis product in tortillas.

Fumonisins are toxic metabolites of Fusarium moniliforme, a fungus that occurs widely in corn. Fumonisins causes leukoencephalomalacia in horses and pulmonary edema in swine and have been suggested as a possible cause of an increased incidence of neural tube defects among people living along the Texas-Mexico border. As part of an effort to determine levels of fumonisins in human food, a liquid chromatographic (LC) method was devised for determining fumonisin B1 (FB1) and the total hydrolysis product of FB1 (HB1) in tortillas. The method uses acetonitrile-0.1M phosphate buffer (pH 3; 1 + 1) extraction, solid-phase C18 cleanup, o-phthalaldehyde and 2-mercaptoethanol derivatization, and reversed-phase LC. Average recoveries from tortillas spiked with FB1 and HB1 at 250, 500, and 1000 ng/g were 86.5% for FB1 and 82.6% for HB1. Tortillas (54) and masa (8) from the Texas-Mexico border were analyzed for FB1 and HB1. Average amounts of FB1 and HB1 in tortillas were 187 and 82 ng/g, respectively. Average amounts of FB1 and HB1 in masas were 262 and 64 ng/g, respectively. The results show that fumonisin B1 and its hydrolysis product are present in tortillas consumed by a population experiencing an increased incidence of neural tube defects.