Feasibility study for a BCR sediment methyl mercury reference material production

A feasibility study to prepare a reference material of methyl mercury (MeHg) is reported. The dry sediment was tested with different solutions to understand how MeHg is bond to sediment matrix. For this we have tested the sediment with water, where all inorganic mercury was extracted, thiosulfate, methanolic KOH, hydrochloric acid and sulfuric acid. The best extractant solution was sulfuric acid with high level of recovery (80%) just in the first extraction. We have evidenced that MeHg can be extracted quantitatively from dry sediment by adding only the minimum quantity of acid to dissolve the calcareous particles to permit the solubilization of the MeHg present inside the particles. We have checked the MeHg stability for about four years, also at room temperature, without significant differences on MeHg content.