The preparation, characterization and separation of isomeric methylmethcathinone(s) from their reduced methylephedrine counterparts using Hydrophilic Interaction LIquid Chromatography (HILIC).

Turnbull, Christopher Philip (2017) The preparation, characterization and separation of isomeric methylmethcathinone(s) from their reduced methylephedrine counterparts using Hydrophilic Interaction LIquid Chromatography (HILIC). Masters by Research thesis (MSc), Manchester Metropolitan University.

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Abstract

This thesis is concerned with the synthesis and characterisation of the ortho-, metaand para-regioisomers of methylephedrine prepared from their corresponding regioisomeric methylmethcathiones. The method principally reduced the carbonyl group (of the cathinone) to a secondary alcohol using sodium borohydride. Crystallisation of the target molecules as their corresponding hydrochloride salts was accomplished using HCl in dioxane (55 – 67% yield). Structural characterisation of the each individual regioisomer was accomplished using a variety of techniques including Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS), Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR), and Ultra Violet – Visible Spectroscopy UV-VIS. High Performance Liquid Chromatography (HPLC) was used to separate each individual regioisomer around the aromatic ring. This was achieved by Hydrophilic Interaction Liquid Chromatography (HILIC) with Hichrom ACE 5 SIL column and a mobile phase consisting of acetonitrile and aqueous ammonium formate [90:10% v/v]. This method showed a range of Limit of Detection (LOD) values over the three isomers from 0.05 - 0.07 μg mL-1 for methylmethcathinone and 0.09 - 0.28 μg mL-1 for methylephedrine. A range was also observed for the Limit of Quantification (LOQ) for these compounds, which was 0.15 - 0.22 μg mL-1 and 0.28 -0.83 μg mL-1 respectively. The method displayed robustness in terms of the mobile phase composition, flow rate and temperature and, following testing with street samples, could be applied to real world applications.