Deoxynivalenol and its conjugates in beer: a critical assessment of data obtained by enzyme-linked immunosorbent assay and liquid chromatography coupled to tandem mass spectrometry.

Enzyme-linked immunosorbent assays (ELISAs) are often employed for the control of deoxynivalenol (DON) in barley and other intermediates involved in beer production chain. Because of the occurrence of high levels of DON-3-glucoside (DON-3-Glc) in malt and beer that have been reported for the first time in our earlier study, research focused on the accuracy of DON determination by immunoassays in cereal-based matrices has been initiated. DON-3-Glc was strongly cross-reacting in all examined commercial ELISA test kits (Ridascreen) DON (R-Biopharm), Veratox 5/5 DON) (Neogen Corporation), Deoxynivalenol EIA (Euro-Diagnostica), and AgraQuant) DON Assay 0.25/5.0 Test Kit (Romer Labs). The highest overestimation in beer analysis, up to 1000%, when taking the DON content determined by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) as a reference method, was obtained by AgraQuant assay. Besides of DON-3-Glc and 3- and 15-acetyldeoxynivalenol (ADONs), also other, not known yet, matrix components contributed to false positive results. Similar phenomenon, although in a lesser extent due to lower content of these substances, was observed for using ELISA in the analysis of wheat. The relationship between a way of sample handling and DON overestimation was demonstrated; higher ELISA response was measured in an aqueous extract compared to that prepared by acetonitrile-water (84:16, v/v). Most of cross-reacting co-extracts were removed by MycoSep# 226 cartridge, what leads us to the hypothesis on the presence of currently unknown cross-reactive species.