Novel psychoactive drugs (NPS) are a range of drugs that have been designed to mimic established illicit drugs, such as cannabis, MDMA, cocaine and LSD, and as such circumvent existing laws. Positional isomers of NPS are difficult to analyze because they challenge the separation and detection techniques commonly employed by forensic laboratories. Flip flop chromatography is a liquid chromatography technique whereby a single column is utilized for the same analyte(s) in two different separation modes, without the need to change solvent reservoirs. In this vein the utility of silica hydride (SIH) stationary phases, operable under both reversed phase (RP) and aqueous normal phase (ANP) conditions, for the ultra-high performance liquid chromatography separation of synthetic cathinone positional isomers will be presented. The separation of eight positional isomers of the synthetic cathinone pentedrone, was investigated using five SIH phases, and compared to the use of a bimodal pentaflurophenyl column and utilizing a classical dual column RP, hydrophilic interaction chromatographic (HILIC) system. The silica hydride silica-C column, which contains no derivatized ligands attached to the silica hydride backbone, not only gave the most uncorrelated separation of the SIH columns but provided a unique separation of all eight positional isomers (resolution ≥ 1) using the combination of RP and ANP chromatographic conditions. The use of SiH phases, in contrast to the use of a classical RP column and a classical silica column operating under HILIC conditions, allows for rapid equilibration times for both RPC and ANP without the necessity of changing columns.

Flip flop chromatography using silica hydride based stationary phases for the separation of synthetic cathinone positional isomers

ACS Spring Meeting 2021

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