Title : The influence of protein precipitation methods on uncontrolled conversion of cannabidiol to 9-tetrahydrocannabinol during analysis of plasma samples
The growing popularity of supplements containing cannabidiol (CBD), mainly CBD oils, in self-medication of humans and the increased interest in this compound in different preclinical and clinical trials stimulates the development of procedures of CBD analysis in plasma for the study of CBD pharmacology in people and animals or in establishing dose–therapeutic effect relationships of this compound. Preliminary removal of protein by its precipitation from plasma is still one of the willingly applied plasma sample preparation methods in many analytical procedures estimating plasma drug concentration, including CBD. The present paper shows that a significant amount of CBD transforms to D9- tetrahydrocannabinol (D9-THC) in a hot GC injection system when acidic precipitation agents, such as TFA, TCA, HClO4, H2SO4, ZnSO4 or CHCl3, are used for plasma protein precipitation. The transformation degree depends on the temperature of the GC injector, the concentration of the precipitation agent and the incubation time of plasma with the precipitating agent. At the CBD plasma concentration equal to 50 ng/ml, which is approximately a mean level for patients treated for epileptic syndromes, the CBD transformation degree can exceed 20 %. The presented results are important not only for analysts cooperating with pharmacologists and for medicine doctors examining the activity of CBD-containing drugs in the therapeutic process, but also for forensic scientists who may erroneously find innocent people guilty of using marijuana or its preparations.
- Plasma protein precipitation is willingly applied in procedures of CBD analysis.
- CBD transforms to ?9-THC in GC injector when acidic precipitation agents are used.
- The transformation degree of CBD to ?9-THC in GC injector can exceed even 20 %.
- The presented results are important both for clinical and forensic investigators (80).