The Use of Single or Serially Coupled Columns and the Effect of Organic Modifier for the Separation of Constitutional Isomers of the Synthetic Cannabinoid JWH 018

Traditional approaches, such as gas chromatography-mass spectrometry (GC-MS), are complemented by adopting new liquid chromatographic methods to separate isomeric drug mixtures that are unresolvable by the former technique. This study investigates a series of liquid chromatographic approaches using both traditional and silica hydride stationary phases. These methods focus on the separation of 11 synthetic cannabinoid constitutional isomers. Seven different columns were used to assess the utility of single and serially coupled column approaches under reversed-phase conditions. The best separation using a single column was the use of a Cogent Pentafluorophenyl (RP PFP) stationary phase, where 9 out of 11 constitutional isomers were separated. Concerning using different single columns with the same organic modifier or different organic modifiers with the same column, all compounds of interest were separated using a combination of RP PFP and RP C18 columns using methanol as the organic modifier. Cogent RP C18 separated all constitutional isomers (R_s = 1) in two separate runs, using methanol and acetonitrile individually. The serial coupling of columns, which did not offer better separation compared to the previous techniques, demonstrated either enhanced or diminished selectivity based on column coupling.