Simultaneous Determination of Five Carbamate Pesticides in Human Whole Blood by QuEChERS-Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry

QuEChERS-ultra high performance liquid chromatography-tandem mass spectrometry was applied for the simultaneous determination of five carbamate pesticides (methomyl, metolcarb, propoxur, carbaryl and isoprocarb) in human whole blood. 10 ng of methomyl-D3 as an internal standard was added into 1.00 mL of whole blood sample, and the mixture was extracted with 2.00 mL of acetonitrile and 30 mg of NaCl. The supernatant was cleaned up with a composite adsorbent containing 150 mg of anhydrous MgSO₄, 25 mg of N-(n-propyl)ethylenediamine and 25 mg of C₁₈, then the analytes were separated on a ZORBAX Eclipse Plus C₁₈ column (2.1 mm×100 mm, 1.8 μm) using a mixture of methanol and 5 mmol·L^-1 ammonium acetate solution containing 0.1% (φ) formic acid as mobile phases for gradient elution. Electrospray positive ionization source was used. Analysis was practised under multiple reaction monitoring mode. Internal standard method was used for quantification. The linear relationships were found with the mass concentration of the five carbamate pesticides in definited ranges. The detection limits (3S/N) were in the range of 0.10-0.50 μg·L^-1 and the lower limits of determination (10S/N) were in the range of 0.50-0.75 μg·L^-1. Tests for recovery were made by standar addition method to blank sample, giving results between 87.5% and 103%, and RSDs (n=6) were in the range of 2.8%-7.9%.