Determination of the Trace Amount of “Methyl Mercury” in Sea Water Using Chelating Resinst

Abstract

A method for determing the trace amount of “methyl mercury” in sea water was studied using macroreticular chelating resins (RGS) containing epithio groups. The chelating resins were prepared by the reaction of the macroreticular glycidyl methacrylate-ethylene glycol dimethacrylate copolymer beads with ammonium thiocyanate dissolved in methaol.
Methyl mercury in sea water was favorably adsorbed on the RGS, w hen sea water was passed through the RGS column at the space velocity (SV) of 50 h^-1. Methyl mercury adsor bed on the RGS column was effectively eluted, when 10 bed volumes of 4 moll/ hydrochloric acid solution containing 0.5 mg/l of sodium thiosulfate were passed through the column at a SV of 5 h^-1 this procedure, inorganic mercury was not eluted.
Methyl mercury in the eluate was extracted first with ben zene and then with glutathione solution from the benzene phase. Methyl mercury in the glutathione solution was analyzed by the following method: the agueous solutions of sulfuric acid, sodium chloride and potassium permanganate were added to the glutathione solution, and then the solution was heated on a water bath for one hour. After cooling the solution, the amount of mercury was determined by a flameless atomic absorption spectrophotometry. The calibration curve for methyl mercury added to sea water was linear over the Hg concentration range from 0.05 ng/l to 0.5 ngl/l. The detectable concentration limit of methyl mercury by this method was 0.05 ng/l.
This method was successfully applied to the determination of methyl mercury in the sea water samples collected in Minamata Bay and the adjacent sea.