Decomposition of cinnabar and organomercurials in geological materials with nitric acid-sulphuric acid for the determination of total mercury by cold vapour atomic absorption spectrometry

Abstract

Data are presented to show that cinnabar (HgS) dissolves very slowly in HNO₃-H₂SO₄ at room temperature and at temperatures below that of a boiling water-bath. On a boiling water-bath, however, cinnabar was found to be decomposed rapidly by this acid mixture. The experiments illustrated the influence of the temperature on the speed of the reaction. On the basis of these experiments a digestion procedure was developed that uses HNO₃-H₂SO₄(2 + 3) for the extraction of total mercury from geological samples (rocks, soils and sediments) containing cinnabar and organomercurials.