STORAGE AND STABILITY OF INORGANIC AND METHYLMERCURY SOLUTIONS

The storage behaviour of mercurychloride and methylmercury chloride solutions in deionized water and in seawater stored in polyethylene (PE), pyrex glass and teflon (PTFE) containers at various concentration levels (4 ppb, 50 ppt, natural seawater concentrations) was studied using various preservatives and container pretreament procedures. For PE bottles, the best results are obtained, after pretreatment of the bottles with an acidified KMnO4 solution, with a 0.05% (v/v) H2SO4+0.02% (w/v) KMnO4 preservative. However, the solution becomes heterogeneous rather fast, due to the formation of a MnO2 precipitate. Acidified (pH 1 with HNO3) deionized or seawater samples stored in pyrex glass BOD-bottles (analyses are carried out in these bottles too) or teflon containers are stable with respect to inorganic mercury for at least 1 month. Instead of acidification an oxidant such as BrCl can also be used to stabilize the solution. Methylmercury solutions (80 ppt) in deionized water (pH 6) and stored in teflon containers are stable for at least 1 month. In glass bottles, the solution should be acidified to pH 1. Methylmercury seems to be unstable in acidified seawater samples (pH 1 with HNO3); after 2 weeks about 60% of the methylmercury is converted into inorganic mercury. © 1990 Springer-Verlag.