Raman spectrometric study of the charring process of lead in sulfur in electrothermal atomic absorption spectrometry

Abstract

The direct determination of lead in sulfur by electrothermal atomic absorption spectrometry with air as the sheath gas at the 200–750 °C charring step, gave a larger integrated absorbance signal for lead than when using argon as the sheath gas. The state of the lead in the sulfur in the charring step was investigated by Raman spectrometry. The state of the lead in the sulfur in a graphite tube in an air stream was a mixture of PbS and PbO₂ at 300 °C, then changed into a mixture of α-PbO, β-PbO and PbSO₄ at 500 °C and β-PbO at 750 °C. Oxidation to β-PbO was incomplete in an argon stream compared with the use of air.