Rapid Quantitative Detection of Cannabinoids using Laser Raman Spectroscopy

The current gold-standard methods for cannabinoid measurement are highly sensitive, yet expensive, sophisticated, and time-consuming. This study investigated the potential of laser Raman spectroscopy as a rapid and straightforward method for the quantitative detection of three major cannabinoids: Cannabidiol (CBD), Cannabinol (CBN), and Delta-9-tetrahydrocannabinol (THC). A series of solutions of the cannabinoids extracted from Cannabis sativa were prepared in Tetrahydrofuran (THF) and measured with a Near-Infrared (NIR)-excited Raman microspectrometer. The Raman spectra were subjected to chemometrics-based multivariate analysis, employing an ordinary least square fitting method. A strong linear relationship (R² > 0.98) was observed between the Raman intensity and the concentration of all studied cannabinoids. A Raman-based prediction model of each cannabinoid was developed based on a leave-one-out cross-validation analysis, which yielded a minimum detectable concentration in the range of 0.23-0.42 mg/ml, as determined by the Root Mean Square Error of Cross Validation (RMSECV). Additionally, characteristic Raman marker bands for each cannabinoid were identified. Overall, this study presented a simple yet effective Raman spectroscopy-based technique for rapid label-free cannabinoid detection and measurement.