Qualitative Analysis of 6 Ephedrine New Psychoactive Substances by Differential Raman Spectroscopy

A method for rapid and non-destructive qualitative analysis of ephedrine new psychoactive substances by differential Raman spectroscopy was proposed. 6 ephedrine new psychoactive substances were detected using a handheld differential Raman spectrometer under the conditions of excitation source wavelength of 785−786 nm, laser power of 200 mW, and integration time of 1 s, and differential Raman spectroscopy data were then dimensionally reduced and visualized for analysis. As shown by the results, there were clear distinctions in the differential Raman spectra of different types of ephedrine new psychoactive substances, and differential Raman spectra could capture small differences in optical isomers. Based on the characteristic peaks at 173, 397, 941, 1040, 1139 cm⁻¹, the optical isomers of pseudoephedrine hydrochloride could be distinguished. Based on the characteristic peaks at 543, 923, 1283 cm⁻¹, the optical isomers of ephedrine hemihydrate could be distinguished. After reducing the dimensionality of the spectral data, its spatial distribution differentiation effect was more obvious, which could effectively distinguish the targets.