Optimization and validation of a method based in a QuEChERS procedure and gas chromatography–mass spectrometry for the determination of multi-mycotoxins in popcorn

In this work a gas chromatography–mass spectrometry (GC–MS) method for multi-mycotoxins (deoxynivalenol, nivalenol, 15-acetyl-deoxynivalenol, fusarenon X and zearalenone) determination in unpopped and popped popcorn was optimized and validated. Fast sample preparation procedure is based on a pre-extraction of fat compounds with n-hexane, extraction of target analytes with acetonitrile and removing of matrix co-extracts by a simple dispersive solid phase extraction employing MgSO4 and C18 sorbents followed by sylilation of the analytes and further GC–MS analysis. The recoveries in spiked samples (20 and 100 μg/kg) ranged from 61 to 118% in unpopped popcorn and from 65 to 89% in popped popcorn, with relative standard deviations lower than 18%. Limits of detection and quantification were lower than 65 μg/kg and 196 μg/kg, respectively. The method was applied in 30 popcorn samples commercialized in Portugal; one sample was positive for nivalenol and zearalenone, at concentrations below the maximum permissible level.