U.S. flag

An official website of the United States government, Department of Justice.

Isomer Differentiation of Novel Psychoactive Substances Using Gas Chromatography Solid Phase Infrared Spectroscopy (GC/IR)

NCJ Number
Lonnie Jones; Lashaundra Fambro ; B. McKay Allred; Natalie Thomas
Date Published
627 pages

After reviewing the historical background for the relatively recent emergence of “novel psychoactive substances” (NPSs), this project addressed one of the problems posed by NPS, i.e., determining which analytical assays have sufficient specificity to resolve NPSs for identification.



Several terms have been tried to capture more inclusively  “designer drugs” and any new chemical introduced into the market of drug abuse. “Novel psychoactive substances” (NPSs) was ultimately adopted by forensic chemists. The sudden appearance of a bewildering array of synthetic cannabinoids, cathinones, and other NPSs presented many problems to the forensic drug chemists attempting to identify the unknown material. The current project addressed one of these issues. The difficulty of differentiating some isomers by gas chromatography and mass spectrometry (GS/MS) is well established, and much has been reported on the demonstration of analytical schemes to differentiate such drugs as methamphetamine, cocaine, MDMA, and heroin from their isomers. This is a more significant issue with NPSs due to their large numbers, sudden appearance, and high turnover, which do not allow for the execution of comprehensive research. Consequently, non-optimized GC/MS data will only support limited conclusions. The current project argues for the application of an orthogonal, analytical technique that provides the discriminating power for NPS isomers with minimal time and research cost. A gas chromatograph infrared spectrometer (GC/IR) has the potential to separate complex mixtures into their individual components and acquire their associated Fourier-transform infrared (FTIR) spectra. In the current project a GC/IR with solid phase IR spectra was evaluated for its analytical specificity by differentiating various NPSs, their isomers, and related compounds. 162 figures


Date Published: January 1, 2022