MULTITOXIN SCREENING METHOD FOR FUSARIUM MYCOTOXINS IN GRAINS

A screening method has been developed for the major Fusarium mycotoxins. It allows for analysis of trichothecenes derived from nivalenol (NIV), deoxynivalenol (DON), scirpentriol (Sctol), and T-2 tetraol (T-2tol) as the parent alcohols. The toxins are extracted with acetonitrile-methanol-water (80: 5:15), and primary purification on a cation-exchange/alumina-carbon column is followed by hydrolysis and then, after neutralization, by a further purification on a carbon-Celite minicolumn. Quantification is by HPLC/UV (NIV and DON) or GC/ECD (NIV, DON, Sctol, T-2tol). Recoveries of parent alcohols and representative ester derivatives spiked into wheat and maize extracts at 0.5-mu-g/g equiv were in the range 55-103%. Levels of 0.05-mu-g/g or less are detectable by the method. The method gives improved stability of extracts after hydrolysis compared to an existing method; hence, results are more reliable and consistent. The hydrolysis step may be eliminated for analysis of individual trichothecenes. Estimated concentrations of trichothecenes (as parent alcohols) in maize samples commonly increased when analyzed with hydrolysis relative to analyses performed without hydrolysis. This suggested the common occurrence of trichothecene esters as well as the parent alcohols in naturally contaminated samples. An additional part of the method allows for cleanup of a second aliquot of extract using a C18 solid-phase column. This portion produces separate fractions suitable for the analysis of moniliformin and zearalenone, both by HPLC. Mean recoveries for moniliformin and zearalenone from blank samples fortified at 0.5-mu-g/g were 78% and 72%, respectively. Both toxins could be detected down to 0.01-mu-g/g, but for moniliformin, coextractive interferences in some samples and the need for peak confirmation at a second wavelength made identification difficult below 0.1-mu-g/g.