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Quantification of crystallinity in substantially amorphous materials by synchrotron X-ray powder diffractometry
Cletus Nunes1, Arumugam Mahendrasingam, Raj Suryanarayanan
1Department of Pharmaceutics, University of Minnesota, Minneapolis, MN 55455, USA.
Pharmaceutical Research
|September 1, 2005
Summary
A new synchrotron X-ray diffraction (XRD) method quantifies crystallinity in amorphous pharmaceuticals with 0.2% sensitivity. This advanced technique improves detection limits for crystalline content in amorphous matrices, aiding in stability assessments.
Area of Science:
- Pharmaceutical analysis
- Materials science
- Crystallography
Background:
- Quantifying crystallinity in amorphous pharmaceuticals is crucial for assessing physical stability.
- Conventional X-ray diffraction (XRD) methods have limitations in sensitivity for detecting low levels of crystalline content.
Purpose of the Study:
- To develop a highly sensitive powder X-ray diffraction (XRD) technique for quantifying crystallinity in amorphous pharmaceuticals.
- To utilize synchrotron radiation and a 2-D area detector for enhanced sensitivity and data acquisition.
Main Methods:
- Acquired diffraction data using synchrotron radiation and a 2-D charge-coupled device detector.
- Monitored the in situ isothermal crystallization of amorphous sucrose at temperatures ranging from 90 to 160°C.
- Developed an algorithm to separate crystalline and amorphous intensities from the total diffraction pattern.
Main Results:
- Achieved a time resolution of 40 ms for powder diffraction pattern recording.
- Demonstrated that the in situ crystallization approach effectively managed sample inhomogeneity.
- Established an estimated limit of detection for crystalline sucrose at 0.2% w/w, a significant improvement over conventional XRD.
Conclusions:
- High-intensity XRD can detect subtle changes in material lattice order.
- Early detection of crystallization serves as an indicator of potential physical instability in pharmaceutical products.