Abstract: In this work, ultra-high performance liquid chromatography (UPLC) with sample pretreatment by high-throughput automatic purification using immunomagnetic beads was used to accurately determine the content of zearalenone in grains. The reaction time of immunomagnetic beads with zearalenone and the extraction solvent composition were optimized, and the purification effects of immunomagnetic beads on different grain matrices were evaluated. The detection limit and quantitation limit of UPLC were 3.5 and 12.0 μg/kg, respectively. Under the optimized conditions, the recoveries of spiked negative whole wheat and corn flour samples were 99.04%–109.26%, with coefficients of variation not greater than 6.88%. The results of the UPLC method for zearalenone in the national certified reference materials or quality control samples for whole corn flour, whole wheat flour, brown rice flour and wheat flour agreed with the certified values within the extended uncertainty range with coefficients of variation not greater than 3.54%. Analysis by the Bland-Altman method indicated that the difference between immunomagnetic bead purification and immunoaffinity column purification was acceptable. Thus, the two methods could be used interchangeably with each other to purify and enrich zearalenone from grains. The automatic mycotoxin purification system based on immunomagnetic beads, allowing the high-throughput automatic purification of zearalenone from grains, could purify 10–24 samples simultaneously, and it averagely took 2–3 minutes to purify one sample. In conclusion, UPLC has the advantages of rapidity, high sensitivity and high accuracy and can be used for the determination of zearalenone in grains.

Key words: immunomagnetic beads; ultra-high performance liquid chromatography; grains; zearalenone