Direct determination of trace amounts of silicon in iron oxide by graphite furnace and flame atomic absorption spectrometry using halocarbon vapour for fluoride evolution

Abstract

The fluorination of different chemical forms of silicon has been studied using copper(II) hydroxyfluoride solid reagent and C₂Cl₃F₃ vapour in a graphite tube furnace. The method of transportation of the evolved substances from this type of furnace into an acetylene-dinitrogen oxide flame and suitable techniques for handling solid samples were elaborated. The internal gas (Ar) of the furnace was used as the carrier on volatilisation of the halocarbon liquid, which ensured simple operation. The detection limit was 0.84 µg l^–1 of Si in iron oxide when taking 40 mg of solid sample and evaluating the peak absorbance measurements. The average RSD was 4.7% in the concentration range 8–36 µg l^–1 of Si.