Analysis of corrosion residues by WDXRF

In this article, a methodology for the wavelength dispersive X‐ray fluorescence analysis of corrosion residues is described. Corrosion residues are generally composed of elements that are, total or partially, in a reduced state. Therefore, to prepare fused beads to be measured by wavelength dispersive X‐ray fluorescence, it is necessary to oxidize species and to avoid any analyte loss, as sulfur, which is present in residues composition. The combination of an oxidizing agent (LiNO₃) and a flux (Li₂B₄O₇ + LiBO₂), at a mass ratio residue : oxidizing agent : flux of 1:5:12, is demonstrated to be suitable for the quantitative retention of sulfur in the sample preparation. The addition of silica to the mixture (residue : oxidizing agent : flux) for the formation of homogeneous fused beads is also studied. The optimal parameters for the sample preparation are as follows: A temperature of 600 °C for 15 min for the oxidation process and a fusion temperature of 950 °C for fused beads preparation. The quantitative retention of sulfur in the entire process was validated by an independent method, combustion and infrared detection, and analyzation reference materials. Moreover, minor and major elements (Al, Ca, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, S, and Ti) present in corrosion residues were simultaneously measured with low uncertainty. Copyright © 2017 John Wiley & Sons, Ltd.