AbstractAn emission spectrographic method for the quantitative determination of 17 trace elements in high‐purity lanthanum oxide has been developed. The sample was ignited in muffle furnace at 850° for onehourto remove the moisture and carbon dioxide, then blended with equal amount of graphite and 10mgsof this mixture was taken into electrodes. A 10 amps dc are was employed to excite the mixture and a 3.4 meter Ebert Spectrograph with 15,000 LPI plane grating was used to record the spectrum in the region 2,200 at 3,400 Å. The weak line of lanthanum was used as an internal standard. The working ranges of these elements were: Ag, Mg 0.5 to 50ppm; Be 0.5 to 100ppm; V, Cr 1 to 100ppm; Cu, Sn, Fe 3 to 100ppm; Ge, Mn, Ni 5 to 100ppm; B, Co, Pb, Sb 10 to 100ppm; Ca and Si 30 to 500ppm. The precisions fell in the range of 10 to 24%.Samples obtained from Engineering Research Laboratory (ERL) of Institute of Nuclear Energy Research were also exami