Determination of pesticides in human plasma using SPME by LC-MS/MS: a new tool for the assessment of occupational pesticide exposure in the cannabis industry

Description:
The analysis of residual pesticides in commercially available cannabis products has been gaining interest. However, occupational exposure to pesticides used in the cannabis industry has not yet been extensively studied. To determine the occupational exposure level to pesticides, plasma analysis is often performed. As plasma is a complex matrix, any pesticide analysis protocol requires a robust sample preparation method that can clean up the plasma to reduce the matrix effect and to enhance the sensitivity by pre-concentrating the analytes. Therefore, a high throughput method was developed for the determination of 82 pesticides commonly used in cannabis from human plasma by using solid phase microextraction (SPME) coupled to liquid chromatography (LC)- tandem mass spectrometry (MS/MS). Three different SPME extraction phases (mixed mode-polyacrylonitrile (MM-PAN), hydrophilic/lipophilic balance-polyacrylonitrile (HLB-PAN), octadecyl-polyacrylonitrile (C18-PAN)) were evaluated and HLB-PAN was selected as the optimal phase. Stability of the pesticides in the desorption solution was verified up to 3 weeks. The developed SPME protocol was validated according to Food and Drug Administration (FDA) guidelines. Moreover, QuEChERS, a common sample preparation and cleanup method for pesticides analysis in complex samples, was validated, and compared to the developed SPME method. Both methods were able to extract 79 pesticides from human plasma with an accuracy range of 70-120%. Overall, the developed SPME protocol showed significantly less matrix effects (<5%), a higher throughput (1.5 min per sample), and greater sensitivity for most analytes with LOQs of 0.01 µg/L, in comparison to the QuEChERS protocol.

Speaker: Nipunika H. Godage - Department of Chemistry and Biochemistry, College of Natural Sciences and Mathematics, The University of Toledo, Toledo, OH 43606, USA
Nipunika H. Godage is a Ph.D. Candidate at the Department of Chemistry and Biochemistry of the University of Toledo, in Dr. Gionfriddo’s research group. Her research focuses on applications of Solid Phase Microextraction for environmental exposure and health risk assessment.