X-ray Powder Diffraction Pattern Indexing for Pharmaceutical Applications

Crystal-structure determination using X-ray diffraction from single crystals is a well-developed technique (1). A single crystal structure provides full structural characterization of the form at the atomic scale. The main drawback to single crystal diffraction is the need to grow a sufficiently large and defect-free crystal for analysis, which is not practical for all crystal forms. Furthermore, a single crystal is not always representative of the polycrystalline material from which it was obtained. Xray powder diffraction (XRPD) is an ensemble analysis that is generally representative of a powder material, and utilizes powder samples that are often easier to produce than single crystals. For these reasons, XRPD is used routinely for the characterization of crystalline solids.