Rapid In Situ Detection of THC and CBD in Cannabis sativa L. by 1064 nm Raman Spectroscopy

The need to find a rapid and worthwhile technique for the in situ detection of the content of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in Cannabis sativa L. is an ever-increasing problem in the forensic field. Among all the techniques for the detection of cannabinoids, Raman spectroscopy can be identified as the most cost-effective, fast, noninvasive, and nondestructive. In this study, 42 different samples were analyzed using Raman spectroscopy with 1064 nm excitation wavelength. The use of an IR wavelength laser showed the possibility to dearly identify THC and CBD in fresh samples, without any further processing, knocking out the contribution of the fluorescence generated by visible and near-IR sources. The results allow assigning all the Raman features in THC- and CBD-rich natural samples. The multivariate analysis underlines the high reproducibility of the spectra and the possibility to distinguish immediately the Raman spectra of the two cannabinoid species. Furthermore, the ratio between the Raman bands at 1295/1440 and 1623/1663 cm(-1) is identified as an immediate test parameter to evaluate the THC content in the samples.

Automated summary

Finding a fast and effective technique for real-time detection of THC and CBD in cannabis is a pressing issue in the field of forensics. Raman spectroscopy, with its cost-effective, fast, noninvasive, and nondestructive properties, is identified as the most suitable method. This study utilized Raman spectroscopy with 1064 nm excitation wavelength to analyze 42 different samples. The results demonstrated the high reproducibility of spectra and the ability to immediately distinguish between THC and CBD through Raman spectroscopy. Furthermore, the ratio between Raman bands at 1295/1440 and 1623/1663 cm(-1) was identified as an immediate test parameter for evaluating THC content in the samples.