Professor Eric J. Munson of the University of Kansas is supported by the Analytical and Surface Chemistry program to develop methods to improve the analysis of pharmaceuticals using solid-state NMR spectroscopy (SSNMR). A magic-angle spinning (MAS) NMR probe that contains multiple spinning systems is being constructed. The probe design enables the spinning systems to be rapidly shuttled in and out of the homogeneous region of the static magnetic field. While the spectrum of one sample is being acquired, the magnetization of the other samples are returning to equilibrium in the inhomogeneous region of the field. The multiple sample capabilities increase sensitivity and throughput compared to conventional MAS probes. The project is also investigating fundamental problems related to the formulation of new drug compounds. One area focuses on improving the capabilities of solid-state NMR spectroscopy to identify, detect, and quantify polymorphs, solvates, and amorphous forms of a pharmaceutical solid. Another is determining how relaxation and line width are related to the physicochemical properties of the drug, such as particle size and crystal defects. A third area is applying the knowledge gained from measured NMR parameters to drug stability, with the ultimate goal of using solid-state NMR as a predictive tool for early identification of stable formulations.
The SSNMR technology being developed is providing new tools for the characterization of drug formulations. The advances can also be applied broadly to the analysis of pharmaceuticals and samples that include glasses, polymers, and catalysts. The project is providing training for graduate students and enabling collaborations with the pharmaceutical industry.