Separation and identification of the synthetic cathinone isomers dipentylone and N-ethylpentylone using chromatographic and mass spectral characteristics

Abstract

Synthetic cathinone isomers exhibit very similar structure and physicochemical properties, which makes them unable to be effectively separated and identified, therefore increasing the likelihood of misidentification. In this study, the chromatographic and mass spectral characteristics of a sample by gas chromatography-mass spectrometry (GC–MS) were highly like those of N-ethylpentylone. The powder, however, was finally identified as dipentylone (also known as N, N-dimethylpentylone) by high performance liquid chromatography-linear ion trap-orbitrap mass spectrometry (HPLC-LTQ-Orbitrap-MS) and nuclear magnetic resonance (NMR). Because of the possibility of misidentification, the collision-induced dissociation (CID) and electron ionization (EI) pathways of dipentylone and its isomer N-ethylpentylone were further examined to assist forensic laboratories in identifying the synthetic cathinone isomers in their case work. The separation of the two isomers was successfully achieved through ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS). These results demonstrate that the methods developed in this study can be used to separate and identify the two isomers.