螢光X線分析における試料重量について

抄録

X-ray fluorescence analysis requires comparatively large amounts of samples when conventional sample holders are used. However, in the laboratory, rapid and completely non-destructive quantitative analysis by using the X-ray fluorescence technique permits the use of small samples and results are as accurate and precise as those obtained when using the large amounts of samples.
For testing the use of small samples in the laboratory, samples were prepared by brequetting pure magnesium borate, cadmium sulfide and barium oxide. Two methods of exposing the surface areas to primary X-ray beams were then used. In the first method, the minimum amounts required for analysis of the pure chemical briquettes were 0.3g for magnesium borate, 1g for cadmium sulfide and 0.5g for barium oxide by exposing the entire surface to primary X-ray beams. It was found that a minimum sample of 1 g was needed, if the three chemicals were mixed with varying amounts of each in any one sample. Minimum weight of samples was inversely related to the total mass-absorption coefficient, rather than to the density or the thickness of the samples. The lower the total mass-absorption coefficient, the greater the amout of samples required.
In the second method, when various portions of the center surface area were masked before exposure to primary X-ray beams, it was found that the decreases in the fluorescent intensity ratio were less than 10% if the exposed area was greater than 60% of the standard surface area (11.3cm²).