Forensic hyperpolarisation using SABRE

Tennant, Thomas (2018) Forensic hyperpolarisation using SABRE. Masters by Research thesis (MSc), Manchester Metropolitan University.

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Abstract

The purpose of this study is to develop the application of Signal Amplification By Reversible Exchange (SABRE) hyperpolarisation to New Psychoactive Substance (NPS) analysis. Piperazine derivatives are the compounds under investigation due to their strong prevalence in the last ten years as a New Psychoactive Substances (NPS) which posed/poses a threat to the general public, particularly the younger generation. Firstly, this study aimed to fully characterise 1-[(2-pyridyl)methyl]piperazine, 1-[(3-pyridyl)methyl]piperazine and 1-[(4-pyridyl)methyl]piperazine (2, 3 and 4-PMP respectively). Secondly, it was important to develop a quantitative method for detection of these compounds using bench top 1H Nuclear Magnetic Resonance (NMR). Standard addition (SA) and Internal Standard (IS) calibrations were the methods investigated for their suitability. The largest part of the project was to explore the feasibility to hyperpolarise the compounds under investigation due to the presence of a pyridyl functionality. Hyperpolarisation can lower detection limits, cut costs and offer quicker and better results than conventional NMR. SABRE was the hyperpolarisation method employed due to its ease, low cost and impressive literature results. The final aim was to develop/optimise and apply a method to extract and detect the NPS from a common formulation. It was discovered that 3 equivalents of triethylamine was the optimum amount to freebase 4-PMP.3HCl. The method of standard addition using bench-top NMR was incredibly accurate in determining the concentration of PMP samples with unknown concentrations. Finally, a mixture of all three isomers was distinguishable through the use of GC-MS. In addition to this, it was also possible to extract the drug from a common formulation (tablet) in its un-hyperpolarisable state, freebase it and then successfully hyperpolarise. This thesis provides an acceptable application of SABRE to the analysis of NPS.