Stability and reactions of mercury species in organic solution†

Abstract

The stability over time of elemental mercury, methylmercury and inorganic mercury species was evaluated in heptane, toluene and mixed hydrocarbon solutions. Elemental mercury and inorganic mercury(II) were determined using a specific extraction method followed by ICP-MS or CVAAS. Methylmercury and mercury(II) were determined by GC–MIP-AES after derivatisation with Grignard reagent. The results show that significant losses of mercury species from solution can occur by two pathways: by adsorption on the container wall and by reactions forming mercury(I) compounds. For the latter pathway, rapid losses of dissolved elemental mercury and mercury(II) chloride species occur when both are present in solution. For heptane solutions containing HgCl₂, 80% of the HgCl₂ remains after 13 d in a pure standard compared with 11% in a standard containing Hg⁰. Mercury(I) compounds form a colloidal material, which is not soluble in these organic solvents at a detectable concentration. Mercury(I) compounds were butylated with Grignard reagent to form the organic mercury(I) compound (C₄H₉)₂Hg₂ that was measured specifically by GC–MIP-AES and GC–MS. This new compound was stable and appeared to precipitate from solution.