Diffractogram of chemical grade NaCl, with peak positions inserted, for 10 selected peaks. ID of a material is routinely determined by comparison of peak positions from XRD analysis with peak positions from reference material.
ID analysis: We conduct routine XRD analysis for identification purposes, according to Ph. Eur. 2.9.33., using a standard scan program over the interval: 2°-60° 2Θ. All 2Θ ranges between 2° – 153° are available upon request.
Quantitative analysis: Quantification of crystalline or amorphous content in a sample is determined by use of a calibration line, relating peaks intensities to crystalline sample content.
Knowledge about crystallinity is highly relevant, as a crystalline form is usually preferred in development: In contrast to amorphous material, a crystal has well-defined properties (melting point, solubility and IDR) – parameters that should be known in order to control your final product.
The XRD method is described in Ph. Eur 2.9.33. The result from an XRD analysis is a diffractogram showing the intensity as a function of the diffraction angles. Positive ID of a material using XRD analysis is based on accordance between the diffraction angles of a reference material and the sample in question.
XRD analysis is based on constructive interference of monochromatic X-rays and a crystalline sample: The X-rays are generated by a cathode ray tube, filtered to produce monochromatic radiation, collimated to concentrate, and directed toward the sample. The interaction of the incident rays with the sample produces constructive interference (and a diffracted ray) when conditions satisfy Bragg’s Law (nλ=2d sin θ). This law relates the wavelength of electromagnetic radiation to the diffraction angle and the lattice spacing in a crystalline sample.
The characteristic x-ray diffraction pattern generated in a typical XRD analysis provides a unique “fingerprint” of the crystals present in the sample. When properly interpreted, by comparison with standard reference patterns and measurements, this fingerprint allows identification of the crystalline form.
X-ray diffraction (XRD analysis or XRPD analysis) is a unique method in determination of crystallinity of a compound.
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