Chemical reactions of lead in graphite furnace atomic absorption spectrometry

Abstract

The chemical reactions of lead in graphite furnace atomic absorption spectrometry (AAS) are determined experimentally by absorbance measurements, X-ray diffraction and molecular absorption. Lead nitrate is decomposed into lead oxide during the drying cycle, which is reduced to metallic lead by the carbon of the tube.

Interference from chloride ions is due to the formation of volatile lead chloride. The formation of this compound can be prevented by the addition of the matrix modifiers ammonium dihydrogenphosphate and ammonium dichromate. These modifiers, which must be applied in great excess, form stable lead phosphates and chromates. The influence of the palladium nitrate modifier on the reactions of lead is also discussed.