A cannabis flower extract can contain abundant THC or CBD alongside much smaller amounts of other cannabinoids. McRae and Melanson validated an LC–MS/MS method for 17 cannabinoids and addressed that range with more than one dilution. Diluting the extract brings abundant analytes into the working range. An undiluted or less diluted aliquot gives the instrument a better chance of quantifying minor compounds.
The investigators analyzed cannabis extracts at 1:100 and 1:10 dilutions and without dilution. They chose reportable concentrations from measurements that fell within the validated range. They also assessed performance using a candidate cannabis reference material. That material tested performance in a plant matrix, where co-extracted compounds and extraction efficiency can affect a result.
Ask which dilution supported each reported value, what the calibration limits were and how the laboratory handled results outside them. A result below the quantitation limit leaves the amount unresolved at that method’s reporting threshold. It can arise for one analyte while others in the same extract are quantified reliably. The validation applies to the tested cannabis and hemp matrices. A biological specimen would require its own matrix-specific performance evidence.
McRae and Melanson, Analytical and Bioanalytical Chemistry (2020)