Atomic absorption spectrometry of europium and ytterbium in air-hydrogen flame

Abstract

The atomic absorption behavior of europium and ytterbium was studied in an air-hydrogen flame as a cool flame. A Nippon Jarrell Ash AA-1E atomic absorption/flame emission spectrometer and HETCO total-consumption burner were used. Table I shows the experimental conditions.
The effects of inorganic acids in the range of 0.012.5 M on the absorption of europium (300 ppm) and ytterbium (30 ppm) were investigated. Fig. 1 and Fig. 2 show the results. Hydrochloric acid in the range of 12.5 M slightly decreased the absorption of europium and increased that of ytterbium. Nitric acid decreased the absorption of europium by 30% and increased that of ytterbium by twice. Perchloric acid increased the absorption of europium and ytterbium, and the acid in the range of 0.010.1 M increased that of europium by 2.7 times and that of ytterbium by 4.5 times. Sulfuric acid and phosphoric acid remarkably suppressed the absorption of both the elements.
The effects of metal ions in the range of 105000 ppm on the absorption of europium and ytterbium were investigated. Fig. 3 to Fig. 6 show the results. The absorption of europium increased in the presence of potassium of 101000 ppm, and that of ytterbium decreased with increasing the concentration of potassium. Magnesium and aluminum remarkably suppressed the absorption of both the elements, but the interferences with the absorption of europium were eliminated by adding 1% lanthanum. The absorption of europium gradually decreased with increasing the concentration of calcium, and that of ytterbium decreased by 80% in the presence of calcium of 1005000 ppm. The absorption of both the elements decreased with increasing the concentration of Cr, Mn, Fe, Pb, etc. The absorption of europium increased by 20% in the presence of La and Nd more than 100 ppm, and by 50% in the presence of Sm of 1000 ppm, but that decreased with increasing the concentration of Y and Dy. The absorption of ytterbium decreased with increasing the concentration of Y, La, Eu, Dy and Er.
The calibration curve for europium was linear in the range of 0400 ppm. The calibration curve obtained by adding 0.1 M perchloric acid showed a sensitivity of 2.7 times in comparison with that for europium alone. The calibration curve for ytterbium obtained by adding 0.1 M perchloric acid showed a sensitivity of 4.5 times that for ytterbium alone and of 1.8 times that for ytterbium obtained in a nitrous oxide-acetylene flame.
Europium in synthetic or practical samples as rare earth oxide was determined by atomic absorption method using the air-hydrogen flame. A sample was dissolved by perchloric acid, and europium in the sample solution was determined. Table II shows the results. In the determination of europium in the synthetic sample, the found value was in fair agreement with the theoretical value. In the determination of europium in practical samples, the values obtained were in fair agreement with the values obtained by flame emission method using a nitrous oxide-acetylene flame.