Mass spectrometry and equilibrium of oxides of arsenic, gallium and indium in the graphite furnace

Abstract

Calculations of the equilibrium in the reduction of As₂O₃, Ga₂O₃ and In₂O₃ by graphite show that the gas-phase oxides As₄O₆(g), Ga₂O(g) and In₂O(g) may be formed during the analysis for arsenic, gallium and indium by graphite furnace atomic absorption spectrometry (GFAAS). These gas-phase oxides were detected by mass spectrometry during graphite furnace atomisation in vacuo. The As₄O₆(g) is likely to be lost from the furnace during prolonged drying of arsenic samples at relatively low temperatures; Ga₂O(g) and In₂O(g) may be formed during atomisation cycles above 1000 K. These effects may cause substantial losses in sensitivity for these elements during GFAAS.