The application of different analytical techniques is fundamental in forensic drug analysis. In the wake of the occurrence of large numbers of new psychoactive substances possessing similar chemical structures as already known ones, focus has been placed on applied criteria for their univocal identification. These criteria vary, obviously, depending on the applied technique and analytical approach. However, when two or more substances are proven to have similar analytical properties, these criteria no longer apply, which imply that complementary techniques have to be used in their differentiation.

This work describes the synthesis of some structural analogues to synthetic cannabinoids and cathinones based on the evolving patterns in the illicit drug market. Six synthetic cannabinoids and six synthetic cathinones were synthesized, that, at the time for this study, were not as yet found in drug seizures. Further, a selection of their spectroscopic data is compared to those of already existing analogues; mainly isomers and homologues. The applied techniques were mass spectrometry (MS), Fourier transformed infrared (FTIR, gas phase) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. In total, 59 different compounds were analyzed with the  selected techniques.

The results from comparison of spectroscopic data showed that isomeric substances may in some cases be difficult to unambiguously identify based only on their GC-MS EI spectra. On the other hand, GC-FTIR demonstrated more distinguishable spectra. The spectra for the homologous compounds showed however, that the GC-FTIR technique was less successful compared to GC-MS. Also a pronounced fragmentation pattern for some of the cathinones was found.

In conclusion, this thesis highlights the importance of using complementary techniques for the univocal identification of synthetic cannabinoids and cathinones. By increasing the number of analogues investigated, the more may be learnt about the capabilities of different techniques for structural differentiations, and thereby providing important identification criteria leading to trustworthy forensic evidence.