Methods for quantification of cannabinoids: a narrative review

Abstract

Background: Around 144 cannabinoids have been identified in cannabis plant, among them tetrahydrocannabinol (THC) and cannabidiol (CBD) are the most prominent ones. Because of the legal restrictions on cannabis in many countries, it is difficult to obtain standards to use in research; nonetheless, it is important to develop a cannabinoid quantification technique with pharmaceutical applications for quality control of future therapeutic cannabinoids.

Method: To find relevant articles for this narrative review paper, a combination of keywords such as medicinal cannabis, analytical, quantification and cannabinoids were searched for in PubMed, EMBASE, MEDLINE, Google Scholar and Cochrane Library (Wiley) databases.

Results: The most common cannabinoid quantification techniques include gas chromatography (GC) and high-performance liquid chromatography (HPLC). GC is often used in conjunction with mass spectrometry (MS) or flame ionization detection (FID). The major advantage of GC is terpenes quantification however, for evaluating acidic cannabinoids it needs to be derivatised. The main advantage of HPLC is the ability to quantify both acidic and neutral forms of cannabinoids without derivatisation which is often with MS or ultraviolet (UV) detectors.

Conclusion: Based on the information presented in this review, the ideal cannabinoid quantification method is HPLC- MS/MS for the cannabinoids.

Keywords: Analytical; CBD; Cannabinoids; Cannabis; Quantification; THC.

Fig. 1

The most common cannabinoids and their conversion pathway by decarboxylation because of heat or aging. CBGA can convert to CBDA and THCA by CBDA synthase and THCA synthase, respectively. CBGA: cannabigerolic acid, CBG: cannabigerol, CBDA: cannabidiolic acid, CBD: cannabidiol, THCA: tetrahydrocannabinolic acid, THC: tetrahyrocannabinol, CBN: cannabinol (Fathordoobady et al. 2019)

Fig. 2

Cannabis compounds and impurities can be detected by various methods. Some methods are suggested in this figure for specific purposes. ICPMS: Inductively coupled plasma mass spectrometry, XRF: X-ray fluorescence, AAS: Atomic absorption spectroscopy, PCR: Polymerase chain reaction, ELISA: enzyme-linked immunosorbent assay, GC: gas chromatography, LC: Liquid chromatography