Literatuuronderzoek naar de bepaling van zeldzame aarden in drinkwater met behulp van ICP-MS

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The estimated concentrations of the rare earth elements (REE) in drinking water vary between 0.3 ng/l for Lu and 130 ng/l for Ce. Sc, Y, La, Ce and Eu may be determined without preconcentration ; the other REE need a 50-100x preconcentration. This report describes several off-line preconcentration methods like precipitation, extraction and column chromatography. On-line preconcentration with an automated extraction system offers advantages like quick sample analysis (about 4 min), minimal sample handling and minimal contamination. The REE determination by ICP-MS suffers from REE oxide spectral interferences. These oxide levels can be minimized by optimizing the instrumental parameters. The best isotope choice is: 45Sc, 89Y, 139La, 140Ce, 141Pr, 143Nd, 147Sm or 149Sm, 151Eu, 157Gd, 159Tb, 163Dy, 165Ho, 167Er, 169Tm, 171Yb and 175Lu. 115In can be used as an internal standard for sensitivity, 248ThO/232Th can be used as an internal standard for the MO/M ratio. Gaussian correction formulas or principal components analysis (PCA) should be used, if the REE oxide interferences cannot be reduced sufficiently.