Determination of Neonicotinoid Insecticides and Their Metabolites in Human Urine by Response Surface Optimization of QuEChERS Combined with Liquid Chromatography-High Resolution Mass Spectrometry

A QuEChERS-ultra performance liquid chromatography-quadrupole-(UPLC-Q) exactive orbitrap high resolution mass spectrometry method was developed for determination of 12 kinds of neonicotinoid insecticides and 3 kinds of s metabolites in human urine. The separation was performed on an Agilent Eclipse Plus C18 column with a gradient elution of 0.1% formic acid water-acetonitrile as mobile phase. The analytes were ionized in positive heated electrospray ionization (HESI+) and scanned under Full MS-PRM mode. A response surface methodology based on Box-behnken design was used to optimize the amount of salting-out agent and adsorbent in the QuEChERS method. For the extraction and purification, acetonitrile was used as the extractant, anhydrous Na2SO4 and NaCl as the salting agent, and PSA as the adsorbent. 15 analytes showed good linearity in their respective linear ranges with correlation coefficients above 0.999. The limits of detection were 1.0-10 ng/L and the limits of quantification were 3.0-33 ng/L. The method was validated at low, medium and high spiked concentrations. The recoveries ranged from 81.8% to 120.9%, the matrix effects ranged from 80.8% to 117.6%, the intra-day precision ranged from 0.6% to 8.6%, and the inter-day precision ranged from 1.3% to 12.9%. The determination of neonicotinoid insecticide residues in 10 real human urine samples demonstrated the feasibility of the established method. This method possessed a wide linear range, high sensitivity and good precision, and could be applied to both the determination of neonicotinoid insecticide poisoning cases in the field of forensic science and the monitoring of neonicotinoid insecticide residues in human body in the field of environment.