DETERMINATION OF BARIUM IN WATERS BY TUNGSTEN COIL ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

Investigations were carried out on the use of tungsten coils as electr othermal atomizers for the direct determination of low concentrations of Ba by atomic absorption spectrometry (AAS). The thermal treatment o f the analytical sample was carried out in 41 s, a 10 mul sample volum e being used for the determination of Ba in waters in the 10-250 pg ra nge, with good precision (relative standard deviation < 5%). The use o f hydrogen in combination with argon as purge gas was essential for th e 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 atomiza tion of 200 pg of Ba. The interference caused by larger amounts of Ca was minimized by the addition of ethylenediaminetetraacetic acid. It w as 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 i n the analysis of water samples. The detection limit was 2 pg and the characteristic mass was 3.6 pg.