Occurrence of mono- and di-glycosylated conjugates of T-2 and HT-2 toxins in naturally contaminated cereals

An increasing incidence of T-2 and HT-2 toxins (T-2 and HT-2) representing group A trichothecenes has been observed in Fusarium infected small grain cereals in the last decade. Quite recently, the existence of glucosides of T-2 and HT-2 has also been proved next to the common parent forms. There is a strong desire to deepen the knowledge of the occurrence of these conjugates and the possibilities of their analytical determination. A new analytical procedure has been developed for monitoring T-2/HT-2 conjugates in cereal samples. Four different sample preparation methods based on crude acetonitrile: water extraction, QuEChERS, solid phase extraction and immunoaffinity clean-up, were tested. The latter approach employing dedicated immunoaffinity cross-reactive cartridges was shown to be the best option for selective isolation and pre-concentration of the target conjugated analytes. The samples obtained in this way were examined by ultra-high performance liquid chromatography hyphenated to high resolution tandem mass spectrometry that enabled the confirmation of the presence of conjugated T-2 and HT-2. In addition to mono-glycosylated forms of T-2 and HT-2 detected in naturally contaminated barley, wheat and oats, we have also documented for the first time the existence of diglucosides of HT-2 in barley.