Fast determination of neonicotinoid insecticides in beeswax by ultra-high performance liquid chromatography-tandem mass spectrometry using an enhanced matrix removal-lipid sorbent for clean-up

Abstract This study is concerned with the development of a simple, rapid analytical method for simultaneously determining seven neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid and thiacloprid) in beeswax, by means of ultra-high performance liquid chromatography coupled to a quadrupole-time-of-flight mass detector. An efficient sample treatment is proposed (with average analyte recoveries between 93% and 106%) involving solvent extraction with a methanol and ethyl acetate mixture (70:30, v/v), centrifugation, freezing with dry ice, a dispersive solid phase extraction (enhanced matrix removal-lipid) followed by evaporation. Chromatographic analysis (10.5 min) was performed on a core-shell technology-based column (Kinetex® EVO C 18 ). The method was fully validated in terms of selectivity, ruggedness, limits of detection (LODs) and quantification (LOQs), matrix effect, linearity, uncertainty, trueness and precision. Low LOQs, ranging from 1.2 to 4.9 μg/kg, were obtained in all cases. Finally, the proposed methods were applied to neonicotinoid analysis of twenty one beeswax samples from different Spanish regions, only one of the pesticides (imidacloprid) being detected at low levels (