Study of natural occurrence of T-2 and HT-2 toxins and their glucosyl derivatives from field barlet to malt by high resolution orbitrap mass spectrometry

The recent Commission Recommendation 2013/165/EU, asked for collection of more data on T-2 and HT-2 toxins occurrence in cereals and cereal products and emphasized that "in case the used method of analysis enables it, it would be appropriate to analyze also the masked mycotoxins, in particular the mono- and di-glycosylated conjugates of -T2 and HT-2 toxin". Addressing these issues, the aim of this work was to obtain more comprehensive information on the co-occurrence of T-2 and HT-2 toxins and their glucosylated derivatives in naturally contaminated cereal samples. For these purposes, barley samples originating from a Northern Italian area, were analyzed by LC-HRMS for the presence of T-2, HT-2, and relevant glucosyl derivatives. Quantitative analysis of T-2 and HT-2 glucosides was performed for the first time using a recently made available standard of T-2 glucoside. A widespread co-occurrence of the glucosyl derivative of HT-2 with the unconjugated toxin was observed in unprocessed barley grains, whereas the monoglucosyl derivative of T-2 toxin was detected in only a few samples and at low µg/kg levels. The ratio between glucosylated toxins (sum of T-2 and HT-2 glucosides) and native toxins (sum of T-2 and HT-2) ranged from 2 to 283%. Moreover, taking advantage of the possibility of retrospective analysis of full scan HRMS chromatograms, samples were also screened for the presence of other type-A trichothecenes, namely neosolaniol, diacetoxyscirpenol and their mono-glucosyl derivatives, which were detected at trace levels. A subset of nine different samples was subjected to micro-maltation in order to carry out a preliminary investigation on the fate of T-2, HT-2 and relevant glucosides along the malting process. Mycotoxin reduction from cleaned barley to malt was observed at rates ranging from 4% to 87%.