The Rietveld Method as a Tool to Quantify the Amorphous Amount of Microcrystalline Cellulose

With the use of X-ray powder diffraction data and the Rietveld method, we verified that both microcrystalline cellulose PH-101 and PH-102 presented differences in the crystallinity degree. The results revealed these samples are semicrystalline in nature and via Rietveld refinements, it was possible, adding a known amount of an internal standard of corundum to the samples, to perform quantitative phase analyses, which allowed us to determine the amorphous amount of the studied samples: 63.7(11)wt% in microcrystalline cellulose PH-101 and 51.0(11)wt% in microcrystalline cellulose PH-102. An important contribution of this work refers to the attempt of using this simple method, permitting to evaluate the degree of crystallinity of microcrystalline cellulose. (c) 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:1394-1399, 2014