Gadolinium determination in uranium: evaluation of spectral interference from residual uranium and a method for the correction on the estimates

Spectroscopic methods are widely used to analyse rare earth elements in uranium. Inductively coupled plasma atomic emission spectrometry is one important technique in the various types of spectrochemical analytical methods of rare earths. However, if the analysis has to be done for a uranium sample, the rich and complex spectrum of uranium increases the background intensity and interference problems. Rare earth elements in general, and gadolinium in particular are well-known, for their very high neutron absorption cross section and therefore they are to be analysed at ultra trace level in uranium samples. Rare earths in nitrate solutions are separated from uranium samples by solvent extraction and are used for the analysis. In this paper a systematic study of the variation of the intensity at this wavelength position is described. A procedure is suggested to determine the concentration of gadolinium even though uranium is present in the solution at higher concentration than the tolerance limits