THC-COOH Required Derivatization in This GC–MS Method, While Parent THC Did Not
The postmortem method used a derivatization step for THC-COOH to improve chromatography and sensitivity. It did not apply the same final preparation to parent THC.
The two analytes followed different workflows
Parent THC was recovered in an initial extraction and reconstituted for GC–MS. The metabolite underwent a separate extraction after acidification, followed by chemical derivatization. The authors reported poor chromatographic behavior and sensitivity for the underivatized metabolite in their system.
Changing analytical form did not change the original identity
Derivatization creates a form suited to the measurement procedure. It should not be interpreted as evidence that the body originally contained that laboratory derivative or that the metabolite has the same pharmacological effects as THC. Sample preparation and in-vivo metabolism are different processes.
Method dependence matters to comparisons
This finding does not establish that every instrument or analytical platform must use the identical step. It does mean that a result should be interpreted within the workflow actually validated. Comparing sensitivity across assays requires attention to which compound was extracted, how it was chemically prepared and which ions were measured. Analytical improvement does not supply a conversion from metabolite concentration to prior impairment or establish a causal role in death.
Related analysis: the study’s broader findings and limitations.
