Microcrystalline cellulose (MCC) analysis and quantitative phase analysis of ciprofloxacin/MCC mixtures by Rietveld XRD refinement with physically based background

Analysis of microcrystalline cellulose (MCC) PH-101, ciprofloxacin (CIP) and quantitative phase analysis of predetermined mixtures of CIP/MCC were performed by the Rietveld method with a physically based background. Correction factors for absorption and air scattering under a symmetrical reflection geometry with a given sample thickness, divergence and receiving slit width, scale factors, average temperature factors and specimen density of packing, were considered to model the background. By this way, the whole diffraction pattern was evaluated on a physical basis, considering the Bragg and the diffuse scattering (thermal diffuse scattering plus static disorder, Compton and air scattering) using a Python code. Compton scattering was also corrected for the bandpass function of the monochromator. Quantitative phase analysis is discussed on the scope of the results obtained. The maximum absolute difference in the weight% composition obtained was of 3.4% in the CIP/MCC mixtures.