Aerial parts containing cannabidiol can be purchased in a legal way but cannabis used
as recreational drug is illegal in most European countries. Δ9-tetrahydrocannabinol is
one of the main cannabinoids responsible for the psychotropic effect. European
Union countries and Switzerland authorize a concentration of THC of 0.2 % and 1.0
% w/w, respectively, for smoking products and industrial hemp. Public health inspectors
and law enforcement officers need to check the legality of samples. Therefore
there is a need for innovative approaches, allowing quality control of these products
in an easy way and preferably on site. In many countries, cultivation of industrial
hemp is permitted if the THC content does not exceed 0.2 % w/w. A portable equipment
could be a useful measuring tool for farmers to check for the THC content at
regular time. In this work, 189 samples were analysed with a benchtop and a handheld
NIR device in order to create two classification methods according to European
and Swiss laws. All samples were also analysed by GC-FID to determine their THC
concentration. Supervised analysis was applied in order to establish the best model.
For the first classification, the accuracy was 91% for the test set with the benchtop
data and 93 % for the test set with the handheld data. For the second classification,
the accuracies were respectively 91 % and 95 %. The obtained models, hyphenating
spectroscopic techniques and chemometrics, enable to discriminate legal and illegal
cannabis samples according to European and Swiss laws.
