Potentiometric Sensor Array for Analysis of Complex Rare Earth Mixtures

An approach for simultaneous quantification of several rare earth elements (RE) in complex mixtures, using an array of cross-sensitive potentiometric sensors with plasticized polymeric membranes, is reported. 14 different ligands suggested in liquid extraction systems for separation of lanthanides/actinides were employed as membrane active compounds in the polymeric sensors. The sensors of the array were found to have high potentiometric sensitivity towards lanthanide ions in acidic solutions with pH 1.5. The array of 28 sensors was applied for simultaneous determination of three RE metals in four sets of model mixtures simulating technological solutions of spent nuclear fuel reprocessing process. Multivariate calibration models calculated with PLS1 algorithm revealed that analysis of Y, La and Gd in mixtures with uranyl nitrate is possible with RMSEP values 0.29, 0.17 and 0.28 logCMe correspondingly (confirmed by independent test set). Determination of Nd, Sm and Gd in mixtures with uranyl (RMSEP=0.250.26 logCMe) and with thorium (RMSEP=0.280.37 logCMe) is also possible.