Determination of trace amounts of thallium in nickel-based alloys by electrothermal atomic absorption spectrometry

Abstract

A method is described for determining trace amounts of thallium in nickel-based alloys by electrothermal atomic absorption spectrometry (ETAAS). The alloy was dissolved by two methods, one a microwave digestion procedure and the other a hot-plate dissolution method. Different acids were used for each of the two different methods. For microwave digestion, a combination of H₂SO₄, HNO₃ and HF acid was used, whereas for hot-plate dissolution, a combination of H₂SO₄, HF and H₂O₂ was used. Ascorbic acid (C₆H₈O₆) was used as chemical modifier. Comparable results for Tl are achieved by the two methods of dissolution. The installation of a stabilized temperature platform in the graphite furnace tube improves the absorbance signal and the precision of the measurement. The detection limit was 0.1 ng ml^–1 of Tl (3s_b). The accuracy of the method was elucidated through the analysis of certified nickel-based alloys.