Suggest me your idea or any publication.
Many thanks in Advance!
I normally use internal standard like silicon powder, by mixing the sample with known amount of silicon, and do Rietveld refinement of the XRD spectrum.
Some diffraction software, such as Bruker's Diffrac.Eva, have an option to estimate the crystallinity of a sample based on the peak area to total diffractogram area . This gives only a very rough estimate, but it may be useful sometimes. Unlike the method described by Mr. Suwarno ,this method is not really suited for quantitative results.
The best method is to add an internal standard in a known amount (I use about 30% of corundum) that should be mixed with the sample. After the collection of the XRPD pattern you can perform the Rietveld refinement. Tthe software Topas (Bruker) for example allows the estimation of the crystallinity degree.
If your software suite does not include a module for Reitveld analysis, you can get software here.
http://www.rietica.org/
It depends on whether or not you are able to differentiate crystalline peaks clearly and separate them out from interfering peaks of other excipients. Sometimes you are able to identify one or two sharp peaks that vary linearly or logrithmically with crystalline fraction. Some other times you have to take multiple peaks simultaniously for quantitation. In multiple peaks situation, we found that chemomterics with pca and pla as the best way to quantitate. Essentially you need both crystalline and amorphous api for calibration plots. You may want to refer to some of recent papers on tacrolimus for further details. In medline just search for "Mansoor Khan FDA". - Best wishes.
This might be obvious, but I wanted to point out that if a portion of your sample is amorphous, it will not show any signal in PXRD, and therefore you cannot tell from PXRD what % of the sample is x-tal and what % is amorphous.
Obviously, it is a relative amount of crystallinity that is measured. If it doesnt show anything it is 0% crystallinity. The other extreme is 100% crystallinity. The rest fall in between depending upon ratios of amorphous and crystalline material, and this is needed for calibration before looking at the actual sample. Hope it clarifies.
Dr. V. Ranjithkumar
Crystallinity index is the ratio of the crystalline peaks to the crystalline+amorphous peaks. Amorphous peaks are the noise in XRD data, while, from crystalline+amorphous, we mean the whole XRD profile. In the following 17 min video, I have explained in detail the crystallinity index and how to calculate it from XRD data. In the first 2.5 min, I have first explained 'what is meant by the crystallinity index'. In the rest of the video, I have taught 'how to calculate the crystallinity index from XRD data in origin for crystalline as well as amorphous materials. If you need anything further to ask, let me know. I'll appreciate your feedback on the video tutorial. I have attached the discussed files (Origin file and Excel template) here, as well as, they can be accessed from the description in the video. Thanks
How to calculate crystallinity index from XRD data using origin
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