Abstract
A reliable ultra-high-performance liquid chromatography-tandem mass spectrometry method (UHPLC-MS/MS) was developed for the simultaneous determination of two mycotoxins, that is, zearalenone (ZEN) and zearalenone-14-glucoside (ZEN-14G) in formula feed, concentrated feed, and premixed feed products. An improved sample pretreatment was achieved with the hydrophilic-lipophilic balance (HLB) cartridges efficiently removing the impurities and enriching the target analytes in different feeds. The critical parameters affecting the performance of the solid-phase extraction (SPE) procedure were carefully optimized, and 20% acetonitrile in water as the loading solution, 50% methanol in water as the washing solvent, and 5 ml of methanol as the elution solvent yielded the optimal purification efficiencies. The established method was thoroughly validated in terms of linearity (R 2 ≥ 0.999), sensitivity (limit of quantification in the range of 0.50-5.00 μg kg-1), recovery (89.35 ± 2.67% to 110.93 ± 1.56%), and precision (RSD, 3.00-14.20%), and it was then successfully applied to investigate a total of 60 feed samples. Among them, 50 samples were found to be contaminated with ZEN (an incidence of 83.3%) at levels ranging from 0.63 to 615.24 μg kg-1, whereas 22 samples were contaminated with ZEN-14G (an incidence of 36.7%) in the range of 0.89-15.31 μg kg-1. The developed method proved to be a specific and reliable tool for intensive monitoring of ZEN and ZEN-14G in complex feed matrices.