I made a suppository of clotrimazole in a macrogol base and did a XRD analysis on it and also the macrogol base itself.
The macrogol base had three peaks where the intensity of the peaks started at around 100 (y-axis). In the diffractogram of the clotrimazol in the macrogol base, the same three peaks was noticed. But the intensity of the peak started at 300.
The amorphous area also increased in the intensity.
Why does the amorphous and crystalline area increase when the drug is mixed in the macrogol base?
(I've uploaded pictures of the diffractogram)
From these intensity-ratios and area under the peaks, you can get an approximate ratio of amorphous and crystalline contributions in your sample. For crystalline material, as the X-ray penetrates through the material and gets reflected by successive Bragg planes, it gets detected by the detector and cps increases. So, for a particular penetration-depth, the (hkl) planes that come more frequently will have higher intensity and vice-versa.
The area under the peaks generally remain constant. For smaller particles and higher strain-levels, the intensity drops and FWHM increases. But, the ratio of intensities and area under the peaks are much more fundamental properties for a specific material.
Abdelkader Dehbi Souvik Bhattacharjee So just be sure, the reason for the intensity of crystalline stays the same is becbause the ratio of crystalline constribution is the same. And the reason for the intensity of amorphous ratio is increasing is because clotrimazole becomes amorphous?
Oguzhan Saglam On a rough view, it looks so, as you asserted in the last comment. But, I would recommend a series of further characterizations to be sure of the associated mechanisms.
From XRD data you can only understand crystal structure and combination of phases. Now, back to your question.
If you see the peak broadening is happening with addition of said material into your drug, then it implies the amount of drug is amorphous with a crystalline structure. Also, amorphous structure does not have a specific structure due to polycrystalline behaviour. So, you can calculate the amount of crystalline phase to amorphous phase by calculating the area under the peak. Once you have these value then calculate the ratio. You will understand what is happeing once you add said material into your drug.
The intensity of the peaks also depends on the orientation of planes. The better orientation of planes can be normally achieved by homogeneous grinding of the sample. By seeing your Macrogol and Macrogol + clotrimazole PXRD pattern, one can say that both the pattern is the same (with the difference in peak intensity and baseline) within the shown 2thetha range. A full pattern will be helpful to explain. Possible cause of differences in both patterns may be due to,
1. Grinding of samples (if not homogeneous)
2. Sample height while taking the data
3. Mixing of two materials loose crystalline nature by the interaction of materials with each other.
From XRD data you can only understand crystal structure and combination of phases. Also, amorphous structure does not have a specific structure due to polycrystalline behaviour. So, you can calculate the amount of crystalline phase to amorphous phase by calculating the area under the peak.
Dear Oguzhan, in the diffraction patterns, the background line is calculated incorrectly. Under the peaks, this line goes up, which is just wrong. You should change the settings of the background calculations by e.g. turning off the convexity, or change the convexity factor. It will be acceptable, if the line is straight under a peak. If you do not correct it, the results of quantitative analysis of the peak intensities (the integral ones, of course) will be worth nothing.
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