Direct determination of small quantities of rare earth and yttrium oxides in thoria by emission spectroscopy.

Methods are proposed for the determination of submicrogram quantities of rare earth and yttrium oxides in thorium oxide by emission spectroscopy, without previous separation or concentration of these oxides in the sample. It is possible to volatilise these refractory materials from the thoria using silver chloride as the carrier. The carrier distillation technique in conjunction with relatively high dispersion spectroscopy (0.8-1.1 A/mm) makes possible analyses at levels which were previously only feasible by preconcentration methods (e.g., La(2)O(3) and Y(2)O(3), 5 ppm; Nd(2)O(3) and Sm(2)O(3) 10 ppm; CeO(2) and Pr(6)O(11), 20 ppm in a 10-mg sample of ThO(2)).