A contribution to the improvement of accuracy in the quantitation of THC.

The accuracy of a quantitative analysis is highly dependent on the quality of the reference standard. Although reference standards are more and more supplied with a certificate, laboratories may feel the need for additional acceptance testing. In general, confirmation of the purity of many solid reference substances can be obtained by a number of simple tests. However, verification of the true content of reference solutions may be complicated. A number of problems with the THC quantitation caused our interest for a verification method for the THC reference solution. The quantitation of THC is performed by gas chromatography with flame ionisation detector. The effective carbon number concept was used to predict GC/FID response factors. Equations and data are presented to calculate theoretical response ratios of cannabinoids. The experimental data for CBD and CBN were in excellent agreement with the theoretical ones. The paper shows that the response factors of CBD and/or CBN can be used for the calculation of the THC content of either reference solutions or cannabis samples.