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Development of analytical methods to study cannabis and derived products

par Duchateau, Céline
Président du jury Stévigny, Caroline
Promoteur Pochet, Stéphanie
Co-Promoteur Deconinck, Eric
Publication Non publié, 2023-12-20

Thèse de doctorat

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Résumé :

This work focuses on the development of analytical methods of cannabis and itsderivatives. It is important to check the legality of these products and the quality of the oilused for products present legally and illegally on the Belgian market. These products mustcontain a maximum Δ9-tetrahydrocannabinol (Δ9-THC) content of 0.2 % (w/w) in EuropeanUnion (EU) countries and a maximum of 1 % (w/w) in Switzerland. Among the panel offormulations available on the Belgian market, this work was limited to two forms: cannabisflowers and cannabidiol (CBD) oils.The first part of the thesis is focused on flower samples. The samples were analyzed bynear infrared spectroscopy combined with chemometrics using handheld and benchtopdevices. Classification models have been developed to differentiate herbs forsmoking/agricultural hemp from cannabis seized at the festival. A GC-FID referencemethod is used to determine the Δ9-THC content.Smoking herbs are usually issued with a certificate of analysis whose cannabinoid contenthas been determined using the liquid chromatographic method. Differences between theresults obtained with the official method based on (GC-FID) and laboratory methodsbased on (ultrahigh performance) liquid chromatography combined with diode arraydetector (UHPLC-DAD) are often encountered. A study comparing the validationparameters of the official method and a UHPLC-DAD method developed in our labs wasconducted. Moreover, a t-test was performed to compare the CBD and Δ9-THC contentsobtained with the different methods.The second part of the thesis is focused on CBD oil samples. First, a GC hyphenated withtandem mass spectrometers (GC-MS/MS) method was developed as well as a sampleclean-up in order to be able to routinely analyze several samples without damaging thecolumn. The developed method also makes it possible to control the Δ9-THC content aswell as detect the presence of other cannabinoids. The CBD content of samples seizedby Federal Agency for Medicines and Health Products (FAMHP) was then determinedusing this method. The samples were then analyzed by near infrared and mid infraredspectroscopy using benchtop devices. Classification models were developed to check theconformity and quality of the oil matrices according to the label claim. In addition,prediction models were created to predict the CBD content in these samples. The conceptof the method has been effective.