Development of a simultaneous analysis method for 13 neonicotinoids and related insecticides in whole blood by...

We developed a simultaneous analysis method for 13 neonicotinoids and related insecticides in whole blood by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using a Novum simplified liquid extraction column. The extraction method, which employs an extraction solvent of 16% acetonitrile in ethyl acetate, demonstrated the best performance in terms of balancing phospholipid removal ability, recovery efficiency and matrix effects. Calibration curves showed good linear relationships, with r² values exceeding 0.995. The intra- and inter-day accuracies and precisions were 85.5-108.8% and 0.2-13.0%, respectively. The recovery efficiencies were in the range of 52.7-92.7%. Matrix effects were between 60.6 and 201.0%; higher effects were seen for fipronil, which represents a significant challenge that resulted in substantial ion enhancement. Nevertheless, both the accuracy and precision of the method were enhanced by utilization of a stable isotopically-labeled internal standard followed by LC-MS/MS. The method was applied to a human postmortem blood sample collected during a forensic autopsy to demonstrate feasibility; results suggest that this method will be useful for forensic toxicological investigations.