Determination of deoxynivalenol (DON, vomitoxin) in wheat by high-performance liquid chromatography with photolysis and electrochemical detection (HPLC-hv-EC).

Deoxynivalenol (DON, vomitoxin) is a naturally occurring toxic fungal metabolite found in grains such as wheat, corn, rye, and barley. Current methods of analysis for DON and related trichothecene mycotoxins involve gas chromatography with electron capture detection, thin-layer chromatography, and high-performance liquid chromatography with ultraviolet detection. Improved sensitivity and selectivity for DON, as well as for the related compounds nivalenol and fusarenon-X, are made possible by the use of high-performance liquid chromatography with online, postcolumn photolysis and oxidative amperometric detection (HPLC-hv-EC). Conditions are optimized with respect to residence time in the photolytic reactor, applied potentials, mobile phase pH, and chromatographic parameters for the separation of DON, nivalenol, and fusarenon-X, and the technique is found to be linear over a range of 10 ppb-2 ppm with minimum detection limits on the order of 1-2 ng on-column (10-20 ppb). Since these compounds are not electroactive in the absence of photolysis, an additional mode of specificity is realized in addition to the chromatographic retention time and the dual-electrode response ratio. Some market samples of wheat naturally contaminated with DON are analyzed by this method, and the results are in agreement with those obtained by HPLC-UV and TLC analyses of the same samples.