Selective complexometric determination of mercury using acetylacetone as masking agent

Abstract

A complexo-titrimetric method for the determination of mercury(II) in the presence of other metal ions is described, based on the selective masking ability of acetylacetone. Mercury and other ions in a given sample solution are initially complexed with excess of EDTA and the surplus EDTA is titrated with lead nitrate solution at pH 5.0–6.0 (adjusted with hexamine) using Xylenol Orange as indicator. An excess of a 10% alcoholic solution of acetylacetone is then added to decompose the Hg^II–EDTA complex and the EDTA released is titrated with lead nitrate solution. Reproducible and accurate results are obtained for 3–55 mg of mercury with relative errors of <0.3% and standard deviations of <0.04 mg. The lack of effect of foreign ions on the accuracy and precision of the method reveals that the method may be suitable for the determination of mercury in its alloys. The method was successfully applied for the determination of mercury in complexes and synthetic alloy solutions.