An analysis of tetrahydrocannabinol (THC) and its analogs using surface enhanced Raman Scattering (SERS)

We present an analysis of the adsorption geometry of THC and its analogs (cannabinol, cannabidiol and HU-210) on silver using Surface Enhanced Raman Scattering (SERS) technique along with DFT calculations. Our study shows that these cannabinoids are oriented parallel to the silver surfaces and form bonds using primarily the benzene rings and oxygen atoms. In addition, we examine the effect of four different salts: MgCl2; MgSO4; KNO3; and Na2SO4 on SERS enhancements of these drugs. We observe that MgCl2 causes the greatest enhancement for most of these drugs. We attribute this enhancement to the increase of the electric field induced by Mg2+ salts and the formation of SERS active sites. This work also provides evidence that each salt most likely affects the orientation of all four cannabinoids in a similar way on a silver surface, resulting in a production of similar SERS spectra.