Total pattern analyses for non-crystalline materials

Abstract

A total pattern analysis suite of programs has been developed and incorporated into the ICDD® PDF-4 database. While the suite of programs is intended for the analysis of any diffraction pattern, particular attention was focused on the analysis of common amorphous, non-crystalline, or partially crystalline materials found in minerals, polymers, and pharmaceuticals. The suite of programs directly interfaces to the ICDD database and libraries of non-crystalline references.

A practical guide to pharmaceutical analyses using X-ray powder diffraction

“…Many methods were originally developed for inorganic or mineral analyses; however, workshops at PPXRD have clearly demonstrated applications to pharmaceutical analyses (Kern et al , 2015, 2016) as well. Similarly, amorphous materials can now be analyzed by their scattering profiles when using full pattern methods, as shown for amorphous Montelukast™ (Fawcett et al , 2015), povidones (Teng et al , 2010), and absorbed water (Bates, 2013). With full pattern methods, numerous authors cite the critical importance of careful background measurements to separate various scattering contributions of the instrument and specimen holder from the analyte of interest.…”

Formulation analyses of high-volume prescription drugs

“…Either direct measurement of the crystallite size, as incorporated in many Rietveld programs, or a crystallite size model (Scardi et al ., 2005, 2006) can greatly help in the analysis. Full pattern analysis methods with incorporated crystallite size models (Fawcett et al ., 2015a, 2015b) were used in all the analyses. Figure 4, shows alpha lactose monohydrate (PDF# 02-088-5179) with crystallite sizes of 500, 320, and 200 Å that could be compared to the experimental data in Figure 3.…”

“…A complete review and analyses were presented at PPXRD-13 (Fawcett et al ., 2015b) but in this case the analyses involved the full pattern modeling of the broad features (red and green experimental data in Figure 8) caused by the combination of MCC and amorphous sodium montelukast. Using a standard addition experiment, the concentration of sodium montelukast in the formulation was calculated at 4 wt.…”

“…In this publication we tried to show the value of using full pattern methods. The analysis of Singulair ® demonstrates how low concentrations of an amorphous API or excipient can be analyzed (Fawcett et al ., 2015b). Similar methods were used to identify povidone in Allegra ® .…”

“…Therefore, powder patterns were collected in approximately 1 hour. The scan range was specifically selected to enhance phase identification using total pattern analysis methods (Fawcett et al ., 2015a, 2016, 2017). The low angle limit of 5° 2 θ , enabled the detection of many common silicates and stearates used in pharmaceutical formations.…”