Acetonitrile: the better extractant for the determination of T-2 and HT-2 toxin in cereals using an immunoaffinity-based cleanup?

The complete extraction of the analytes is the most important item during the analysis of matrix samples. Within the discussion, which of both extractants-aqueous methanol or aqueous acetonitrile-is the best for the extraction of the mycotoxins T-2 and HT-2, a recently published work pointed out, that the latter one resulted in incorrect high toxin concentrations. Due to water absorption of dry samples and salting out effects, a phase separation of the extractant occurs and the toxins accumulate in the organic layer. Based on these results, investigations were performed by comparing and evaluating the extraction efficiency of methanol/water and acetonitrile/water-the most frequently used extractants for T-2 and HT-2 toxin. Therefore, a reliable and routine capable method combining the extraction with acetonitrile/water and a cleanup with immunoaffinity columns was necessary. Due to the sensitivity of the antibodies against acetonitrile, the cleanup of extracts containing acetonitrile was critical. A modified workup based on the investigated antibodies' tolerance of 5% of acetonitrile was established. The method was validated according to common guidelines (linearity, limit of detection/limit of quantitation, accuracy, method precision, recovery). Especially for more complex matrices a better extraction efficiency with acetonitrile/water was obtainable, simple or unprocessed matrices resulted in identical toxin concentrations independent from extraction solvent.