A Tantalum Foil-Lined Graphite Tube for the Analysis of Arsenic and Selenium by Atomic Absorption Spectroscopy

Abstract

Methods for the carbon rod analysis of selenium and arsenic in wastewaters which employ commercially manufactured graphite atomizers have recently been described. The selenium studies were performed with the graphite minifurnace described by Matousek and Stevens (Varian Techtron model 61 CRA), while the arsenic studies employed a 9 mm × 3 mm i.d. graphite tube as the atomization chamber (Varian Techtron model 63). A major advantage in using the carbon tube was the ability to increase the optimal sample volume from 0.5 μl to 5.0 μl, thus improving relative detection limits. A serious drawback was an accompanying increase in nonspecific background absorption, which in this case was attributed to scattering effects from the sample matrix. In order to overcome the scattering problems, the samples were subjected to precipitation/ion exchange to lower the salt concentrations in order to facilitate the use of a hydrogen continuum lamp as a reliable means of background correction.