Trace Analysis of Hexavalent Chromium in Chromium Compound by X-Ray Photoelectron Spectroscopy

Abstract

Chromium metal and oxides are important elements in RoHS regulation. On this account some analysis methods are proposed to detect the trace concentration of CrO₃ (less than 1000 ppm) in Cr compound, especially, as method detecting CrO₃ in high sensitivity, the diphenylcarbazide coloring method is usually used. There is XPS as technique to analyze at valence number of Cr by non-destruction and quickly. However, XPS method is not spread in CrO₃ (6+) detection, regardless to be able to distinguish CrO₃ (6+) from Cr₂O₃, because the detection limit of XPS is not good. In this study, we inspected a detection limit of XPS for Cr with standard samples (standard samples for fluorescence X-rays analysis), and furthermore, the detection limit of valence number in XPS inspected it with some samples. As the results, it was shown that the detection limit for chromium of XPS was about 200 ppm (mass %) and asymmetry function (Sherwood function) is effective analysis function for curve fitting of Cr 2p_3/2 peak.