Simultaneous determination of multiclass pesticide residues in human plasma using a mini QuEChERS method

Blood is one of the most assessable matrices for the determination of pesticide residue exposure in humans. Effective sample preparation/cleanup of biological samples is very important in the development of a sensitive, reproducible, and robust method. In the present study, a simple, cost-effective, and rapid gas chromatography–tandem mass spectrometry method has been developed and validated for simultaneous analysis of 31 multiclass (organophosphates, organochlorines, and synthetic pyrethroids) pesticide residues in human plasma by means of a mini QuEChERS (quick, easy, cheap, effective, rugged, and safe) method. We have adopted a modified version of the QuEChERS method, which is primarily used for pesticide residue analysis in food commodities. The QuEChERS method was optimized by use of different extraction solvents and different amounts and combinations of salts and sorbents (primary–secondary amines and C18) for the dispersive solid-phase extraction step. The results show that a combination of ethyl acetate with 2% acetic acid, magnesium sulfate (0.4 g), and solid-phase extraction for sample cleanup with primary–secondary amines (50 mg) per 1-mL volume of plasma is the most suitable for generating acceptable results with high recoveries for all multiclass pesticides from human plasma. The mean recovery ranged from 74% to 109% for all the analytes. The limit of quantification and limit of detection of the method ranged from 0.12 to 13.53 ng mL-1 and from 0.04 to 4.10 ng mL-1 respectively. The intraday precision and the interday precision of the method were 6% or less and 11% or less respectively. This method would be useful for the analysis of a wide range of pesticides of interest in a small volume of clinical and/or forensic samples to support biomonitoring and toxicological applications.