Enhanced Sensitivity and Effective Cleanup Strategy for Analysis of Neonicotinoids in Complex Dietary Samples and the Application in the Total Diet Study

Extensive residues of neonicotinoids (neonics) have been demonstrated in food and environment by routine monitoring measurement, but little is known about the residue levels in "ready to eat" dietary samples. To obtain a more accurate picture of dietary exposure to total neonics, an ultra-sensitive and effective cleanup analytical method for the quantification of neonics in dietary samples was established based on cold-induced phase separation and pre-column dilution injection (PDI) liquid chromatography-high resolution mass spectrometry (LC-HRMS). A total of 10 neonics were quantified in ultra-trace amounts (ng/kg) using stable isotope dilution with calibration curves spanning four orders of magnitude. Satisfactory accuracy (73.5-109.2% for the recoveries) and precision (0.6-13.2% for the RSD ranges) were obtained in method validation. Moreover, tolerable absolute matrix effects (0.89-1.09) were also obtained in 12 kinds of dietary matrices with weak relative matrix effects (2.8-12.6%). The validated met...