![]() Quantitative phase analysis by PXRD is not trivial. At some point, it may be advantageous to determine quantitatively the level of amorphous content in the samples. PXRD can be used to screen for the relative crystallinity of samples. Discussionĭuring the development of a drug substance synthesis, initial material may be completely amorphous or poorly crystalline. The data presented were obtained with a typical Bragg-Brentano powder diffractometer using a copper X-ray source and a nickel filter at the detector to provide diffraction data using λ= 1.54 Å. ![]() The majority of this article will focus on a simple approach that does not require standards and is suitable for routine pharmaceutical development. The purpose of this article is to briefly mention the various PXRD approaches to quantify amorphous content. While less-routine XRD techniques may provide a lower limit of detection/quantitation for amorphous content, in the author’s experience, 10% amorphous content is a practical lower limit for detection using typical PXRD equipment. For pharmaceutical samples with amorphous content within the range of approximately 10 to 90% w/w, powder X-ray diffraction (PXRD) provides a means to determine the relative amorphous content. ![]() Powder X-ray diffraction is considered the ‘gold standard’ for identifying and quantifying crystalline phases in materials as diverse as minerals to active pharmaceutical ingredients. Randall et al discussed the various uses of PXRD to pharmaceutical development as applied both to drug substance and drug product. Powder X-ray diffraction (PXRD) is one of several significant tools used to characterize the solid state character of drug substances. Amorphous content within the crystalline drug substance may have a deleterious impact on the drug product such as reduced chemical and physical stability. Typically, the desired solid state for active pharmaceutical ingredients (drug substance) is crystalline. ![]()
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