Determination of selenium by graphite furnace atomic absorption spectrometry. Part 1. Interaction between selenium and carbon

Abstract

Factors important for the interaction between various types of graphite materials and selenium in the absence of modifier were investigated. By employing radioactive measurements and constant temperature graphite furnace atomic absorption spectrometry it was found that in the presence of hydrogen, selenium compounds could be volatilised during drying from a pyrographite surface. However, stability up to 1773 K could be realised in an argon atmosphere if an activated graphite surface was used. A two-step atomiser with independent control of analyte volatilisation and atomisation made it possible to investigate the reactions between vapourised selenium species and graphite. In uncoated polycrystalline graphite tubes heated to 1173–1573 K 90% of volatilised selenium species were retained as compared with 15% in a pyrolytic graphite coated tube. The equilibrium distribution of condensed as well as gaseous selenium species as a function of temperature and partial pressure of oxygen is given in order to provide support for the experimental results.