A simple and efficient QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) sample preparation method was modified to provide good analytical results for 14 mycotoxins in rice. The method involved mixing sample with acidified aqueous acetonitrile, followed by salt-out liquid partitioning using MgSO4, NaCl, and citrate buffer salts. The extract was cleaned-up by dispersive solid-phase extraction with MgSO4, PSA, C18, and alumina-neutral. The analysis was performed using ultra-high performance liquid chromatography coupled to triple-quadrupole tandem mass spectrometry (UHPLC-MS/MS). Throughout the validation experiments, 70-98% overall recoveries were achieved with RSDs ⩽ 7% for most analytes at concentrations 10-100 μg kg(-1). Limit of detections were 0.5-15 μg kg(-1). Inter-laboratory precision was performed by proficiency testing, |z|⩽ 2 was considered satisfactory. We compared our modified QuEChERS method against sample preparation using an immunoaffinity column; the recovery and specificity were comparable for the two methods, but the QuEChERS approach was more time- and cost-effective.
Keywords: Foods analysis; Mycotoxin; QuEChERS; Rice; Tandem mass spectrometry; Ultra-high performance liquid chromatography.
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