Quantitative analysis of crystalline forms
Identification of polymorphs in pharmaceutical products is a leading X-ray diffraction (XRD) application. The detection and quantification of polymorphic contamination is used to improve production efficiency and cost. In the study of different polycrystalline structures, within a drug compound, one polymorph is distinguished from another by a unique powder diffraction pattern associated with that specific crystal structure. Phase analysis can be restricted to qualitative identification only or can be extended to a full quantitative analysis. The analysis is applicable to polymorphs or to multi-component formulations. A special case of this type of analysis is "percentage crystallinity," where the volume percentage crystalline active ingredient to an amorphous filler is measured within a dosage formulation. X-ray diffraction analysis is also employed to study dosage formulations, under a variety of environmental conditions and over time, to characterize the formation of any polymorphs that could adversely affect performance and toxicity.
Graphite and diamond are considered to be polymorphs, which means they are identical in the chemical aspect, but very different when it comes to crystal structure.