Chemometric application operating a portable laser infrared sensor detecting illicit phenethylamines

Abstract

We are presenting a chemometrical application designed to recognize compounds having a molecular structure similar to the main controlled stimulant and hallucinogenic illicit phenetylamines, i.e. to amphetamines and their main precursors, the ephedrines. The input database contains their infrared laser spectra, which have been recorded with a new portable GC - IR sensor, in the spectral domain (1405 - 1150 cm^-1), specific to its quantum cascade laser (QCL) source of electromagnetic radiation (UT8).  A discriminating w_TE feature weight was first determined by using the spectra of the targeted positives and the spectra of various compounds of forensic interest. The input database, formed with the w_TE² preprocessed laser infrared spectra, has been subjected to Principal Component Analysis (PCA). The scores plots have been analyzed in order to evaluate to what extent the amphetamines and their main precursors, the ephedrines, are forming specific and successfully distinguishable clusters. The results indicate that the application meets the requirements of forensic analytical tools.