Improved instrumental sensitivity for Cd determination in aqueous solutions using Wavelength Dispersive X-ray Fluorescence Spectrometry, Rh-target tube instrumentation

This work was aimed at improving the instrumental sensitivity and detection limits for Cd determination in liquid samples by using conventional Wavelength Dispersive X-ray Fluorescence (WDXRF) instrumentation equipped with Rh-anode X-ray sources.The fact that the background is drastically reduced when using activated membranes as a preconcentration tool to collect Cd from liquid samples permits an improvement of the sensitivity compared with the direct analysis of liquid samples.Instrumental WDXRF parameters, as well as the study of Cd-K and Cd-L series spectral lines, were evaluated to select the best conditions for Cd quantitation. The Cd-Lα spectral line was found to be the best choice in terms of sensitivity and repeatability. The calculated detection limit when this spectral line was used to carry out the measurements was 0.17 mg L− 1 Cd, which is suitable for Cd determination in most liquid samples involved in environmental studies.