Determination of barium in waters by tungsten coil electrothermal atomic absorption spectrometry

Abstract

Investigations were carried out on the use of tungsten coils as electrothermal atomizers for the direct determination of low concentrations of Ba by atomic absorption spectrometry (AAS). The thermal treatment of the analytical sample was carried out in 41 s, a 10 µl sample volume being used for the determination of Ba in waters in the 10–250 pg range, with good precision (relative standard deviation < 5%). The use of hydrogen in combination with argon as purge gas was essential for the atomization of Ba. The lifetime of the coil was up to 400 firings in 0.014 mol l^–1 HNO₃. No interference from 8000 ng of K, 6000 ng of Na, 1000 ng of Mg, 10 ng of Ca and 10 ng of Sr were found for the atomization of 200 pg of Ba. The interference caused by larger amounts of Ca was minimized by the addition of ethylenediaminetetraacetic acid. It was shown by the paired t-test that there was no significant difference at the 5% probability level between the results obtained by tungsten coil AAS and inductively coupled plasma atomic emission spectrometry in the analysis of water samples. The detection limit was 2 pg and the characteristic mass was 3.6 pg.