The Plasma Method Did Not Intentionally Convert Glucuronides Into Total Cannabinoids
The plasma method did not use enzymatic or alkaline hydrolysis to produce total cannabinoid measurements. Its reported analytes should therefore not be casually equated with a separately hydrolyzed total result.
Preparation included extraction and derivatization
Andrenyak and colleagues developed GC–MS/MS analysis of THC, 11-hydroxy-THC, THC-COOH and CBD in human plasma. The workflow used protein precipitation, liquid–liquid extraction and derivatization. The authors explicitly distinguished it from approaches that hydrolyze conjugates before measurement or directly quantify glucuronides.
Derivatization and hydrolysis are different operations
Derivatization prepares compounds for the analytical technique; it does not, by its name alone, establish intentional measurement of all conjugated material. A concentration described as free, total or directly measured conjugate must match the actual procedure. Comparing reports without that distinction can create an apparent biological difference that is partly a difference in what was measured.
Keep matrix and purpose attached
The method was developed for pharmacokinetic research in plasma, with additional forensic-validation limitations identified by the authors. It did not supply a whole-blood conversion or an impairment threshold. When comparing results, identify plasma versus whole blood, the target chemical form, hydrolysis status and the laboratory’s validation rather than assuming every THC-COOH number represents the same measurement.
Related analysis: the plasma method’s intended research use.
Research cited
Andrenyak and colleagues (2017). Determination of THC, 11-hydroxy-THC, THC-COOH and Cannabidiol in Human Plasma using Gas Chromatography–Tandem Mass Spectrometry. DOI: 10.1093/jat/bkw136.
