2008 Volume 39 Pages 143-150
The Energy Dispersive X-ray Fluorescence Analysis (EDXRF) is a very popular analytical method for screening the specified hazardous elements of electronics parts, whose advantage is to simultaneously inspect the multiple heavy elements in non-destructive manner. However, it is hard to detect light elements with high-sensitivity because the background appears in low-energy side and the excited X-rays are low intensity. Also, the detection efficiency of light elements is affected due to the atmosphere of X-ray beam path, the window material of the detector, and the sample to detector distance.
In this study, for the excitation source for the light elements at the range from sodium to chlorine, the Pd-Lα line (2.838 keV) is collected and obtained with a graphite (2d = 6.708 Å)-made focusing optical element using the Johann type doubly-curved crystal (DCC). For the purpose of reducing background lines and interfering lines, the pseudo-polarization optical system with Bragg angles near 45° is adopted.
As a result, the lower limits of detection (LLD) for light elements is remarkably improved to the sub-ppm level. In our laboratory, for example, analyzing the sulfur in oil, the accuracy of the calibration curves is ensured to excellent linearity R2 = 0.9999, and the detection limit of 0.2 ppm is achieved.
