Researchers at the University of Manchester’s School of Chemistry, working with colleagues in AstraZeneca, have developed a new nuclear magnetic resonance (NMR) technique for analysing mixtures of pharmaceutical species that contain fluorine.
To make safe medicines, the pharmaceutical industry needs powerful tools for chemical analysis. Almost a quarter of all prescription drugs currently on the market contain the element fluorine, but until now, technical problems have made it difficult to use fluorine NMR spectroscopy for detecting and identifying fluorine-containing drugs and their chemical precursors in mixtures. The new method, ‘CHORUS Oneshot’, allows diffusion-ordered (DOSY) spectra to be measured over the full chemical shift range of fluorine for the very first time.
DOSY spectra separate the NMR signals of different chemical species according to size – small molecules have large diffusion coefficients, big molecules diffuse slowly. In a first demonstration of the new technique, the fluorine signals of rosuvastatin (a treatment for high blood cholesterol), a precursor used in the manufacture of rosuvastatin, fluticasone (a synthetic steroid used to treat hayfever and rhinitis), and fluconazole (an antifungal) were all cleanly separated in a single experiment, something that was impossible with previous methods. The new technique will be useful not only in quality control in the pharmaceutical industry, but also in the development of new drugs and in the design of the chemical processes needed to manufacture them.
This research was funded by an Industrial CASE studentship from the Engineering and Physical Sciences Research Council, EPSRC: https://www.epsrc.ac.uk.