Spectrophotometric determination of europium, terbium and yttrium in a perchloric acid solution by the Kalman filter approach

In the presence of perchloric acid, rare-earth elements of europium, terbiu m and yttrium at large concentrations have well-shaped absorption spectra i n the ultraviolet region even without the addition of a chromogenic reagent . However, it is difficult to determine each of them individually, because they have serious overlapping peaks. In this study, a chemometric method, K alman filter, was used to resolve the overlapped spectra and to determine t he individual components. In contrast to conventional implementation of the Kalman filter, an absorption-coefficient matrix derived from a set of mixt ures of known composition by multiple linear regression (MLR) was found to yield better results in this work. For a set of synthetic mixtures of europ ium, terbium and yttrium, their molar absorptivities were determined to be 1945, 3756 and 1446, respectively. The proposed method was also applied to the determination of europium, terbium and yttrium in a sample of phosphor powder product; a satisfactory result was obtained.