Rietveld refinement in the routine quantitative analysis of famotidine polymorphs

Accurate, precise and reliable X-ray powder diffraction method was developed for the quantitative determination of famotidine polymorphic forms in their binary mixtures, which slightly outperforms the previously established Raman method. The study highlights the advantage of focused beam transmission geometry in diminishing the effect of preferred orientation in general, and the straightforward transmission foil sample preparation technique in facilitating high-throughput measurements in particular. This combination can provide good quality data for Rietveld refinement which assures more reliable quantitative results than utilizing intensity ratios of selected single reflections. After careful adjustment of profile parameters, simple routine application of the method was achieved.