DETERMINATION OF YTTERBIUM USING ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY WITH EUROPIUM AS CHEMICAL MODIFIER

The influence of samarium and europium on the determination of ytterbium by electrothermal atomic absorption spectrometry in hydrochloric acid and nitric acid media was studied. Ytterbium was determined in 0.2% nitric acid medium using europium as chemical modifier. The merits of this method are as follows: (1) low atomization temperature, (2) high selectivity, (3) high sensitivity, (4) good repeatability, (5) low detection limit and (6) low memory effect. Many common non-ytterbium rare earth and non-rare earth elements do not interfere. The linear range of the calibration graph for ytterbium is 0-15 ng ml(-1), the characteristic mass is 1.3 pg and the detection limit is 0.25 pg. This method was applied to the determination of trace amounts of ytterbium in a mixture of rare earth oxides and in crude yttria, and satisfactory results were obtained. The relative standard deviations were all lower than 1%. The atomization mechanism of Yb in the Yb-Eu-0.2% HNO3 system was also studied by X-ray powder diffraction.