Polymorph identification in API samples by Solid-state 13C NMR
Polymorphism in crystalline solids is defined as substance with the same chemical composition but different lattice structures and/or different molecular conformations. Polymorphs are different crystalline forms of a substance (APIs) that may have different physicochemical properties, bio-availabilities and activities. When formulating a drug product, physico-chemical stability, solubility and bio-availability of active pharmaceutical ingredient (API) is an important aspect. ssNMR spectroscopy can be employed to investigate polymorphism in API’s by probing the environments of nuclei (1H, 13C, 15N, 19F, 31P etc.) in the solid state and the changes in chemical shift values are often be connected to the changes in conformation or chemical environment of the compound.