Volatile fingerprints of different hashish blocks by means of HS-SPME-GC/MS

In this study, samples collected from different blocks of hashish seized by the Guardia di Finanza in different requisitions have been analysed by means of Head Space – Solid Phase Micro Extraction followed by Gas Chromatography coupled with Mass Spectrometry (HS-SPME-GC/MS). The samples we analysed come from different blocks, which had already been registered with an internal batch number; for each block, the titration of the THC content had been performed by the laboratory of Forensic Toxicology. Overall, we identified more than 170 Volatile Organic Compounds (VOCs) belonging to different chemical classes: terpene (monoterpenes, sesquiterpenes and diterpenes, both oxygenated and hydrocarbons) and non-terpene derivatives. We carried out a multivariate statistical analysis on the results, using both the HCA (Hierarchical Cluster Analysis) and the PCA (Principal Component Analysis) methods. The objective of this study is to evaluate the possibility to determine the differences or the similarities between each sample based on its spontaneous volatile emission profile: this could help the Investigating Judge to evaluate the existence of one or more dealers. This method is fast and doesn’t involve chemical or physical treatment of the sample, thus its simplicity would be a great advantage. The results of the statistical evaluation are very promising, as they show a sharp tendency of the volatile profiles of the samples to gather in clusters based on their batch of origin.