Element Interference Example: The quantitation algorithm operates with a table of elemental regions that are defined for each element and mode of hardware settings. The software calculates the area under the peak above background found in these regions and carries out the math for the appropriate element. For example, in a typical analytical mode, the tungsten and platinum Lb1 lines at 9.67 and 11.07 keV, respectively, are used for quantitation. The software interprets the signal above background in these regions as a positive identification for the given element.
In the example below, the element Germanium in a precious metal alloy is mis-identified as tungsten, owing to the close proximity of the Ge Ka1 line at 9.89 keV with tungsten’s Lb1 line (placing the Ge signal in the element-detection region indicated by the box in the figure below). Also note that the Ge Kb1 line is also close to platinum’s Lb1, causing false positives for Pt in samples having higher Ge concentrations than this one.
XRF analysis of disk of Argentium® Sterling Silver, a tarnish-resistant alloy containing germanium (nominally 92.5% Ag, 6% Cu, 1.5% Ge)
Solutions for an application involving Ge could include: If quantitation is needed, the instrument can be configured to detect Ge while turn off W and Pt in the elemental regions table, or an empirical method for Ge may be used. In the case of a qualitative application, for example, separating regular sterling silver from Ge-containing silver, the spectrum can be used and the quantitation simply ignored, or PASS/FAIL mode using fingerprints can be used.