Evaluation of Phase Identification Methods Using Powder X-ray Different Analysis in Various Pharmaceutical Compendiums / 中国药学杂志

ABSTRACT

OBJECTIVE: To investigate the impacts of particle size and preferred orientation on relative peak intensity, number of peaks and order of peak intensity in powder X-ray diffraction (PXRD) analysis of organic and inorganic pharmaceutical crystalline materials and evaluate the phase identification methods in various pharmaceutical compendiums. METHODS: The PXRD patterns of organic and inorganic materials with different particle sizes obtained by sieving or grinding were acquired and the number of diffraction peaks, peak position and intensity of diffraction peaks were compared across different samples. RESULTS: Due to preferred orientation effects, the diffraction patterns of samples with different particle sizes were apparently different, including the number of peaks, relative peak intensity and the order of the peak intensity. CONCLUSION: Scientists may get different conclusions from the results of same tests performed according to the related guiding principles of current Chinese Pharmacopeia and USP39, EP8.0, JP16 X IV pharmacopoeia for identifying the crystalline forms. The phase identification by PXRD method in current Chinese Pharmacopeia neglects the effects of preferred orientation on diffraction peaks and relative peak intensity. This guideline needs to be updated to better reflect the scientific observation in industry and align with other well accepted compendiums such as USP, EP and JP.