GC-VUV spectroscopy of synthetic cannabinoid isomers, diastereomers and homologs: Increasing differentiation by derivative spectral processing

Abstract

The increased prevalence of synthetic drugs has led to a rise in isomeric compounds on the market, resulting in a need for analysis techniques capable of distinguishing between these analytes. Previous research has investigated the potential of gas chromatography – vacuum ultraviolet spectroscopy (GC-VUV) for this purpose, demonstrating its complimentary nature to the more traditional gas chromatography – mass spectrometry (GC–MS). This work reinforces the value of GC-VUV and demonstrates its potential for GC–MS-like specificity through the application of derivative analysis to VUV spectra. Seventeen JWH 018 positional isomers and six diastereomers, including two homologs, were analyzed by GC-VUV and derivative analysis. Library searches and principal component analysis (PCA) were used to compare the specificity of non-, first, and second derivative spectra. Derivative analysis was found to increase specificity in library searches by lowering the frequency of false hits, and in PCA by improving separation and clustering. This demonstrates the potential value of GC-VUV analysis in general, as well as of the implementation of derivative analysis for isomer identification.