The UK’s Defence and Science Technology Laboratory (DSTL) has officially opened a new, state-of-the-art NMR suite at its site in Porton Down, Salisbury. ‘“What’s in a sample?” may seem like a simple question but may have one of the most difficult answers,’ says Soumya, lead scientist of the new NMR facility. ‘[But] we can now pretty much crack on with anything that comes our way thanks to these new instruments and emerging methods,’ he adds.
DSTL introduced its first NMR machine at Porton Down in 1980 and two additional instruments in 1996. This followed the signing of the Chemical Weapons Convention (CWC) in 1993 – an international treaty that bans the development, production and use of chemical weapons. Over 190 countries are committed to the CWC. DSTL is one of the elite designated laboratories for the Organisation for the Prohibition of Chemical Weapons (OPCW), the chemical weapons watchdog that administers the CWC. It currently ranks amongst the highest performing OPCW designated laboratories worldwide.
The new NMR suite will house several high resolution NMR instruments, including some that have made the move from DSTL’s original NMR building, which was built in the 1970s.
One of the latest NMR instruments installed in the lab is the first of its kind in the UK – it allows scientists to analyse samples at much lower concentrations than previously possible. The NMR suite forms part of DSTL’s chemical analysis capability, which includes a variety of analytical instruments such as gas and liquid chromatography and mass spectrometers. Together these instruments allow scientists at DSTL to analyse a wide range of chemical and biomedical samples, at both the bulk and trace scale, explains Sarah who leads DSTL’s designated laboratory for the OPCW.
‘NMR has been a part of the toolset for alleged chemical warfare attacks nationally and internationally,’ says Andy Bell, DSTL’s chief science and technology officer. This includes supporting police investigations into the Salisbury and Amesbury poisonings as well as identifying the use of chemical weapons in Syria. ‘The nature of chemical warfare is changing [so] we need to have state-of-the-art capabilities to counter that,’ explains Bell.
Fostering collaboration
DSTL works with numerous universities, industrial and governmental partners across the UK and internationally, who will now have access to the new NMR facility. ‘One of the reasons we partner is to bring in fresh and novel ideas,’ says Bell.
Imogen Daniel, a PhD student at the University of Southampton, UK, will carry out some of her research at DSTL. Her research focuses on developing microcoils – small spiralled electrical wires less than 1mm in diameter that can hold up to 1μl of sample – that can increase the sensitivity of NMR. Samples that DSTL analyses are often in trace amounts or insoluble at the higher concentrations that conventional NMR experiments often require, she explains.
Simon Duckett at the University of York is working with DSTL to solve the sensitivity issue of NMR in another way. He explains that nuclei interact only weakly with external magnetic fields, leading to a small population difference between ‘up’ and ‘down’ spins, which is the source of NMR’s relatively weak sensitivity compared to other spectrocopic methods. ‘In every million protons at 1 Tesla [magnetic field strength], there are only 3.5 protons that will contribute to the signal,’ explains Duckett.
One way that his team is trying to increase the signal is by using parahydrogen – a version of the dihydrogen molecule where the hydrogen nuclei have opposing spins. Parahydrogen cannot be detected with NMR as the two opposing spins cancel each other out, causing the molecule to be magnetically neutral. However, reacting molecules such as alkenes or metal complexes with parahydrogen breaks its symmetry. This drastically increases the proportion of molecules that contribute to the signal by up to 200,000 times.
This hyperpolarisation technique can, for example, help chemists follow chemical reactions by detecting short-lived species. For DSTL, using parahydrogen could help detect and analyse low concentrations of chemical and biological samples.
Bell notes that the opening of the new NMR facility coincides with the start of DSTL’s 25th anniversary celebrations. He adds that the new laboratory is a ‘jewel in the crown’ of DSTL. ‘I don’t know what the next 25 years [of research at DSTL] might bring. But I’m sure that NMR will be at the heart of it,’ he says.
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