The postmortem assay’s precision experiments used specified fortified concentrations. Their coefficients of variation were analytical performance measurements, not a complete uncertainty estimate for every case interpretation.
What the validation tested
The authors assessed replicate analyses at 0.1, 0.5 and 1 microgram per milliliter, reporting within-day and between-day coefficients of variation and relative mean errors. They used predefined acceptance criteria for precision and accuracy, with a different allowance at the lower quantification boundary.
These checks tested repeatability and bias under the stated method conditions. Their concentration units and tested levels need to remain attached to any comparison with another assay.
Analytical precision is one component
A small coefficient of variation does not show that collection site, postmortem change or specimen heterogeneity is negligible. Nor does a general acceptance criterion guarantee that the same variation applies at every untested concentration. A numerical result can be analytically reproducible while its biological interpretation remains uncertain.
State the supported conclusion
The validation supports evaluating the laboratory procedure at its tested range and levels. It does not supply a complete error bound for reconstructing behavior before death. A forensic opinion should distinguish measurement performance from uncertainty about exposure history, redistribution and causation rather than folding them into a single laboratory percentage.
Related reading: limits of postmortem cannabinoid reporting.
Research cited
Álvarez-Freire and colleagues (2023). Simple Method for the Determination of THC and THC-COOH in Human Postmortem Blood Samples by Gas Chromatography—Mass Spectrometry. DOI: 10.3390/molecules28083586.
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