The work presented in this thesis describes the development of methods for the analysis of cannabinoids in post-mortem blood samples and hair specimens from cannabis users. It investigates the value of measuring post-mortem blood cannabinoid concentrations and potential value of analysis for cannabinoids in hair for post-mortem toxicology.
The development and validation of a method for analysis of cannabinioids in post-mortem blood is described. The method involved liquid-liquid extraction (LLE) of the cannabinoids ∆9-tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN) and metabolites 11-hydroxy-∆9-tetrahydrocannabinol (11-OH-THC) and 11-nor-∆9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) from post-mortem blood followed by analysis by two dimensional gas chromatography-mass spectrometry (2D GC-MS). The developed method was applied to post-mortem blood samples submitted by Her Majesty’s (HM) Coroners from fatal road traffic collisions (RTCs) and other routine case types (control group).
The prevalence of cannabinoids in the RTC and control group was similar (21% of the RTC group and 26% of the control group were positive for at least one cannabinoid), however, 90% of the cannabinoid positive RTCs had detectable THC (the psychoactive component of cannabis), compared to 60% of the cannabinoid positive control cases. It was demonstrated that it is feasible to indicate possible impairment due to cannabis use in fatal RTCs when the concentration of THC detected is higher than those usually observed in other routine HM Coroners’ cases.
A method was developed for analysis of THC, CBD, CBN and THC-COOH from hair. The method involved LLE combined with solid phase extraction (SPE) from hair followed by analysis by 2D GC-MS and standard GC-MS.
The developed method was applied to 31 authentic hair specimens from regular cannabis users. The method was suitable for detecting exposure (by detection of THC, CBD and CBN) in weekly users but may only prove ingestion in daily users (by detection of THC-COOH).