DETERMINATION OF TRACE AMOUNTS OF THALLIUM IN NICKEL-BASED ALLOYS BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

A method is described for determining trace amounts of thallium in nic kel-based alloys by electrothermal atomic absorption spectrometry (ETA AS). The alloy was dissolved by two methods, one a microwave digestion procedure and the other a hot-plate dissolution method. Different aci ds were used for each of the two different methods. For microwave dige stion, a combination of H2SO4, HNO3 and HF acid was used, whereas for hot-plate dissolution, a combination of H2SO4, HF and H2O2 was used as corbic acid (C6H8O6) was used as chemical modifier. Comparable results for Tl are achieved by the two methods of dissolution. The installati on of a stabilized temperature platform in the graphite furnace tube i mproves the absorbance signal and the precision of the measurement. Th e 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.