Analysis of Polymorphism | Investigating Polymorphism 2 (X-ray Diffractometer)
Analysis of Polymorphism
Investigating Polymorphism 2 (X-ray Diffractometer)
Different crystalline forms of a substance are generally said to have different solubilities. Polymorphism in foods results in different meltability in the mouth; in pharmaceuticals, it results in differences of drug efficacy due to changes in solubility in the body.
An X-ray Diffractometer can be used to check polymorphism.
Fig. 1 shows the analysis of the H2-antagonist Ranitidine, which is contained in medicines for the stomach and bowels.
Form 1 shows the major components. The presence of the Form 2 polymorphs was investigated.
The characteristic Form 2 diffraction line (near 2θ = 20º) is clearly visible, and the presence of Form 2 is confirmed.
|*||The normal method (parafocusing method) achieves poor sensitivity and cannot clearly show the absence or presence of Form 2. The measured profile from the polycapillary method clearly distinguishes between amorphous peaks ("halo peaks") and crystalline peaks and permits accurate crystallinity calculations.|
The conventional parafocusing method achieves poor detection sensitivity for small peaks when measuring drugs in tablet form. Peaks for components with different crystalline form are small and difficult to detect. However, the polycapillary method using a polycapillary lens significantly improves the detection sensitivity by a factor of 4 or 5.