Powder X-ray diffractometers can readily measure bulk samples if techniques are devised for sample preparation, and measurement conditions are properly set. When measuring samples which have curved surfaces, such as pharmaceutical tablets and ball bearings, various effects are seen due to the curvature, such as shifting of the diffraction angle and widening of the full width at half maximum. In the case of samples with these kinds of surfaces, adjustment is done using clay or cellophane tape from the back side of the aluminum sample plate, so that the sample surface is at the same height as the reference surface of the sample plate. The effects of curvature can be reduced by performing the measurement while narrowing the divergence slit and the incident height-limiting slit.
Fig. 1 shows the X-ray diffraction pattern and qualitative analysis results for a pharmaceutical tablet. As a result of measurement, it was possible to identify the active ingredients in the tablet as ibuprofen and ethenzamide.
MiniFlex600 (F.F tube 40 kV, 15mA), Detector: D/teX Ultra, Slit conditions: DS = 0.1 mm, SS = 8 mm, RS = 13 mm, Incident side and receiving side Soller slit: 2.5°, Incident height limiting slit = 2 mm
Scan range: 2θ = 3 ~ 40°, Step width: 0.02°, Scan speed: 4° / min. (about 10 min.)