Method development, residue level analysis, and dietary risk assessment of six morpholine pesticide residues in plant-derived foods based on modified QuEChERS–liquid chromatography–tandem mass spectrometry

A modified QuEChERS purification–liquid chromatography-tandem mass spectrometry method was developed to simultaneously detect six morpholine pesticide residues in plant-derived foods. The samples were extracted using acetonitrile and purified using three adsorbents, namely, graphitized carboxyl MWCNTs , C 18 , and SAX. The limit of quantitation was 0.07–0.75 µg/kg, and the average recoveries ranged from 71.3 % to 113.8 %. The precision ranged from 1.2 % to 13.8 % at four spiked concentrations of 0.5, 1, 5, and 10 µg/kg. The method was applied to analyze 540 samples obtained from 17 types of plant-derived foods collected in Yining, China. Dimethomorph and flumorph were detected in nine types of matrices, and the residue levels did not exceed the maximum residue limits (MRLs) set by the national standard GB 2763–2021. Furthermore, we assessed the risk of acute and chronic exposure to the tested pesticides. The pesticide residue levels were acceptable in all the samples.