DETERMINATION OF THE MYCOTOXIN FUMONISIN B-1 AND IDENTIFICATION OF ITS PARTIALLY HYDROLYZED METABOLITES IN THE FECES OF NONHUMAN-PRIMATES

A method has been developed for the determination of fumonisin B-1 (FB 1) in the faeces of non-human primates (vervet monkeys). The animals w ere dosed with C-14-labelled FB1, and the radioactive compounds in fae ces were recovered by repeated extractions with 0.1M ethylenediaminete traacetic acid. The extracts were cleaned-up on a reversed-phase (C-18 ) solid-phase extraction cartridge, and FB1 was determined by o-phthal dialdehyde derivatization and reversed-phase HPLC. The analytical meth od for the determination of FB1 in the faecal extracts was reproducibl e [2.6% relative standard deviation (RSD)] and accurate (recovery from spiked blank extracts of 93 +/- 2.9% RSD). Confirmation of the identi fication of FB1 in faeces was achieved using HPLC and thin-layer chrom atography, which showed that the radioactivity extracted corresponded mainly to FB1 and a new metabolite with chromatographic properties sim ilar to those of the mycotoxin. The new metabolite was identified by m ass spectrometry and nuclear magnetic resonance spectroscopy to be an equilibrium mixture of the two structural isomers of partially hydroly sed FB,, which are formed by hydrolysis of one of the ester groups of the mycotoxin.