Posted on 14 June 2022
NMR spectroscopy is a hugely powerful analytical technique which allows the structural characterisation of a wide range of molecules and can be used to analyse chemical reactions. However, this method typically requires high-cost instrumentation, with high field magnets, which require cooling with expensive cryogenic fluids. In recent years, low cost, portable benchtop NMR spectrometers have been developed, but these can suffer from relatively low sensitivity and poor signals.
Dr Meghan Halse and PhD student Matheus Rossetto, working with researchers from the University of Edinburgh, have developed and implemented a new experiment which significantly improves the signal internsity on benchtop spectrometers.
This method, the so-called 'SHARPER' experiment, increases the signal-to-noise ratio by a factor of 10 to 30-fold. It achieves this by using a carefully designed magnetic pulse sequence to collapse the target resonance into an extremely narrow singlet. Importantly, the signal is still amenable to quantitative interpretation and therefore this method can still be used in analytical applications like reaction monitoring.
This approach is particularly advantageous when using NMR to anaylse fluroine (19F), which can suffer from poor signal-to-noise ratio Fluorinated organic molecules account for 20% of pharmaceuticals and 60% of agrochemicals produced today. As such, monitoring fluorination reactions and detecting fluorinated compounds are of key importance.
Demonstrating the potential for this methodology to be applied outside the traditional laboratory setting, this method was implemented and optimised during Covid lockdown by remotely connecting to the benchtop NMR spectrometer in the Centre for Hyperpolarisation in Magnetic Resonance (CHyM) in York while working from home. Furthermore the team in York worked remotely with Professor Dušan Uhrín’s team in Edinburgh, using Zoom collaboration to translate the developments in York to a second remotely operated benchtop NMR spectrometer in Edinburgh.
Talking about the research, Dr Halse said: “Benchtop NMR offers the potential to use NMR in wholly new environments as a result of its low cost and portable nature. This ‘SHARPER’ approach significantly improves the spectra that can be obtained and may therefore enable a range of new applications.”
The research is published in Chemical Communications