Volumetric Analysis of Mercuric Salts by EDTA. I

Determination of Mercuric Chloride, Mercury, Mercuric Oxide, Mercurous Chloride, and Ammoniated Mercury

Abstract

When an excess of ammonium chloride-ammonia buffer is added to mercuric salt solution, the salt dissolves as an ammonium complex and this complex undergoes substitution with EDTA. This phenomenon was utilized and mercuric salts were directly titrated with compound EDTA standard solution added with magnesium. This method is characterized by the fact that the presence of chlorine does not interfere in titration. The use of mixed indicator of EBT added with methyl red in this titration was found to give a more clear-cut end point than the use of EBT alone. The titration was carried out on mercury bichloride, mercury, yellow mercuric oxide, mild mercurous chloride, and ammoniated mercury, and results comparable to the assay method in the Japanese Pharmacopoeia were obtained.