Why Thirty Saliva Specimens Could Not Rank Two Cannabis Collection Devices
The thirty authentic saliva specimens in this method study were useful demonstrations of an assay, but they were not a matched comparison that could establish which collection device recovered more cannabinoid from the same people.
The two specimen groups had different exposure histories
Fifteen Quantisal specimens came from five chronic daily cannabis smokers participating in a controlled oral-THC protocol. Their histories included dronabinol dosing and smoking under that research program.
The fifteen Oral-Eze specimens came from three occasional cannabis smokers after a single smoked cannabis cigarette. Thus, collection device, participants, use frequency, route and sampling history differed together. Thirty specimens did not mean thirty independent participants.
A concentration difference has several possible explanations
If one group has higher THC or THCCOOH concentrations, the difference could reflect exposure and collection timing rather than device performance. These authentic specimens cannot isolate the device as the cause because the same participants were not sampled under matched conditions with both devices.
The separate fortified-sample validation experiments remain relevant to analytical performance in each buffer. Those experiments should be distinguished from comparisons between the two authentic-specimen groups.
The appropriate forensic use
The authentic-specimen application supports that the method could be applied to real human oral-fluid samples from those protocols. It does not establish a device conversion factor, a population detection rate or a dose–response relationship. A claimed device advantage requires a design that controls the biological and timing differences.
Related analysis: collection buffers and cannabinoid quantification.
Research cited
Concheiro, Lee, Lendoiro and Huestis (2013), Simultaneous Quantification of THC, THCCOOH, CBD and CBN in Oral Fluid by MicroFlow LC–High Resolution Mass Spectrometry. DOI: 10.1016/j.chroma.2013.04.071.
