OPTIMIZATION OF SAMPLE PREPARATION FOR GRAZING EMISSION X-RAY-FLUORESCENCE IN MICRO-APPLICATIONS AND TRACE ANALYSIS APPLICATIONS

Grazing emission X-ray fluorescence (GEXRF) is a new development in X- ray fluorescence analysis related to total-reflection XRF. An optical flat carrying the sample is irradiated at an angle of approximately 90 degrees with an uncollimated polychromatic X-ray beam. The emitted fl uorescent radiation of the sample elements is measured at very small a ngles using wavelength dispersive detection. For the application of GE XRF in micro- and trace analysis, a sample preparation procedure for a nalysis of liquid samples has been developed. Polycarbonate was invest igated as a possible material for the sample carrier. Homogeneous dist ribution of the sample on the support was achieved by special pre-trea tment of the carrier. This pre-treatment includes siliconizing the pol ycarbonate disks with Serva silicone solution, after which the silicon ized carriers are placed in an oxygen plasma asher, Finally, to obtain a spot of the same size as the X-ray beam (approximate to 30 mm diame ter), a thin silicone layer is placed as a ring on the carriers with a n ear pick. Electron microprobe analyses were performed to check the d istribution of the liquid sample deposit, and GEXRF measurements were used to check the reproducibility of sample preparation. (C) 1997 Else vier Science B.V.