Fully Automated SPE-GC/MS Determination of THC and its Metabolites in Serum Samples

Abstract

This note presents a fully automated analysis system for the determination of THC and its metabolites in blood serum. Automation is based on the GERSTEL MultiPurpose Sampler (MPS) equipped for solid phase extraction and a module for automated eluate evaporation (GERSTEL mVAP). A validated, semi-automated analysis method used for routine analysis was transferred and automated using the described system. Improvements were realized such as a reduction of sample volume and the use of a smaller SPE cartridge format. The method was validated according to Society for Toxicology and Forensic Chemistry (GTFCh) guidelines. Limits of quantification below 1 ng/mL for THC and THC-OH, extraction efficiencies between 70 and 93% and RSDs between 3 and 10% were achieved.The SPE system performs sample preparation in parallel with the chromatographic run, enabling the GC/MS system to operate at maximum capacity.