Criteria for determining purity of Fusarium mycotoxins.

Figure 1. Structures of mycotoxlns used In this study. HO purity of trichothecene standards has been recognized (6), mycotoxin literature lacks nondestructive procedures to determine purity of several of the scarce and expensive trichothecenes. Extensive physicochemical data for characterizing and identifying some 15 mycotoxins (including T-2 toxin and zearalenone) have been published (7). Our investigation is directed toward the development of a nondestructive procedure that can be used to determine purity of purchased or laboratory-prepared reference standards. Physical and chemical properties that may be used to determine the purity of several Fusarium mycotoxlns have been Investigated. A combination of analytical procedures, which Include high performance thin-layer chromatography (HPTLC), liquid chromatography (LC), gas chromatography (GC), gas chromatography/mass spectrometry (GC/MS), ultraviolet spectrometry (UV), and nuclear magnetic resonance (NMR) spectrometry have been used to examine mycotoxin standards obtained from commercial sources and from laboratory fermentations. Results of this InvestIgation IndIcate that commercially available standardS are greater than 90 % pure, but the label weight of purchased reference standards In Individual containers should be verified. Mycotoxin standards, determined to be greater than 98 % pure by HPTLC, LC, and GC/MS, were examined by UV spectrometry and the coefficients of extinction were determined. An Interlaboratory study, Involving 5 collaborators who determined coefficients of extinction (In methanol) for Identical semples, gave the following results: a-zearalenol (>.236 =28 538 ± 558); {3zearalenol (>.238 =24963 ± 747); deoxynlvalenol (>.219 = 6395 ± 349, lot 1), (6020 ± 228, lot 2); and T-2 toxin (>.202 = 3681 ± 255). UV maxima and coefficients of extinction are also reported for HT-2 toxin (>.202 = 1959), dlacetoxysclrpenol (>.203 = 2487), neosolanlol (>.203 = 2644), nlvalenol (>.220 = 5142), and fusarenon-X (>.217 = 5997).