THE SPECTROSCOPIC DETERMINATION OF SMALL CONCENTRATIONS OF LANTHANUM, PRASEODYMIUM, NEODYMIUM, AND YTTRIUM IN CERIUM

The samples to be analyzed are dissolved as the chlorides with CeO/sub 2/ concentrations of 10 mg/ml. One drop of solution is dried on the flat end of a graphite electrode which has been given a preliminary coat of paraffin. The spectra are excited in an a-c arc at a current of 5 amps and recorded with a glass ISP-51 spectrograph using a UF-85 camera. For the determination of lanthanum, praseodymium. neodymium. and yttrium. the following analytical lines (in A) are used for the concentration ranges indicated in parentheses (in%): La 4333.7-Ce 4330.9 (0.0550.62). Pr 4225.3-Ce 4229.6 (0.089-1.29), Nd 4061.1-Ce The error characterizing the reproducibility of the results is 5. 11. 7, and 7%, respectively. In the analysis of highpurity cerium samples. a preliminary concentration of the impurities must be carried out. This is achieved by extracting the cerium from the solution by the addition of 1 mg of YO/sub 3/ per 100 mb of starting CeO/sub 2/ as carrier. Using the analytical lines La 4238.4, Pr 4223.0, Nd 4232.4, and the reference line Y 4235.7 A under the same excitation conditions. the following relative sensitivities are achieved: 0.01% for lanthanum, 0.025% for praseodymium, and 0.028% for neodymium. The over-allmore » error in the analysis, taking conditions. the following relative sensitivities are achieved: 0.01% for lanthanum, 0.025% for praseodymium, and 0.028% for neodymium. The over-all error in the analysis, taking into account the preliminary concentration, is of the order of 10%.« less