Fast determination of neonicotinoid insecticides in bee pollen using QuEChERS and ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

In this study, a new method has been developed to determine seven neonicotinoid insecticides (acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram, thiacloprid and thiamethoxam) in bee pollen using ultra-high performance liquid chromatography coupled to a selective MS detector (qTOF). An efficient sample treatment involving an optimized quick, easy, cheap, effective, rugged and safe method was proposed. In all cases, average analyte recoveries were between 91 and 105%, and no matrix effect was observed. Chromatographic analysis (6.5 min) was performed on a core-shell technology based column (Kinetex® EVO C , 50×2.1 mm, 1.7 μm, 100 Å). The mobile phase consisted of 0.1% formic acid in water and 0.1% of formic acid in ACN, with a flow rate of 0.3 mL/min in gradient elution mode. The fully validated method was selective, linear from LOQ to 500 μg/kg, precise and accurate; relative standard deviation and relative error values were below 8%. Low limits LODs and LOQs were obtained, ranging from 0.6 to 1.3 μg/kg (LODs) and 2.1 to 4.0 μg/kg (LOQs). The method was applied to neonicotinoid analysis in several commercial bee pollen samples from different Spanish regions.