Developing an analytical method for the determination of tetrahydrocannabinol (THC) in recreational cannabis products

Abstract

Cannabis Sativa plant contains various cannabinoids, mainly cannabidiol (CBD) and tetrahydrocannabinol (THC). THC is the major psychoactive component which causes the high effect users desire. Various changes to legislations related to the use of cannabis have occurred over the past 20 years, including decriminalization, recreational legalization use, as well as access to cannabinoids for use as therapeutic medicines in some states or countries. Currently commercially available cannabis products in Malta are labelled to be within the legal limits stating that the percentage of THC is 0.2% or lower. However, there is no testing or reliable evidence supporting this. The aim of this study was thus to develop an analytical method in order to determine the percent of THC in commercially available recreational cannabis products in Malta. A method for the determination of THC in cannabis was developed using Gas Chromatograph – Mass Spectrometry (GC/MS). The method found was acceptable with good resolution of the peaks under investigation: 9.43 minutes for the internal standard, and 12.62 minutes for the THC. The calibration curve produced had an R2 value of 0.990. Three commercially available cannabis products were purchased, extracted, and tested using this method. Two repeat runs for each sample were carried out. The percentages of THC present in each sample were calculated to be 1.125% for sample A, 0.575% for sample B, and 0.750% for sample C. From this study, it could be concluded that the percentages of THC present in each sample did not match with the percentage of THC stated on the labelling of the packets of the samples since they were all higher than 0.2%, which is over the legal limits according to Maltese legislations. The results of this study highlighted the need for regularly testing, monitoring and enforcement of commercially available cannabis products in Malta, in order to make sure that the contents are within limits designated by Maltese law.