Determination of traces of Ni, Co and Fe in Li(2)CO(3)/K(2)CO(3) melts by flame atomic absorption spectrometry.
A flame atomic absorption spectrometry (AAS) method is described for the determination of trace levels of Ni, Co, and Fe in 62 mole percent (mol.%) Li(2)CO(3) and 38 (mol.%) K(2)CO(3) melts after dissolution of the sample in dilute nitric acid. A pneumatic nebulizer with a glass impact bead is used to sample introduction. The effect of the high salt loading of the solution on the analytical signals is minimized by optimization of acetylene flow-rate and height of observation above the burner head. Under the optimum conditions, the results of the analysis of synthetic sample solutions by aqueous standards calibration graphs well agree with those obtained by the method of standard additions. Recoveries ranged from 99 to 101% and the relative standard deviation is around 1%. Detection limits for Ni, Co and Fe in Li/K carbonate salts are similar to that in aqueous solutions, i.e. 0.5x10(-6) g analyte/g (Li(0.62), K(0.38))(2)CO(3). Furthermore, a background absorption is easily compensated by D(2) background correction, which does not affect the sensitivity. The proposed method is applied to the determination of cobalt in real melt samples.
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Dipartimento Energia. Divisione Tecnologie Energetiche Avanzate. Sezione R&S Conversione Elettrochimica dell'Energia, ENEA, C.R.E Casaccia, Via Anguillarese 301, I-00060, Rome, Italy.