With the rapid development of industry, environmental pollutions, especially for heavy metal, have attracted considerable attention. Heavy metal pollutions have become a serious threat to environment and human health, owning to their special chemical properties and toxic effects. As a result, there is an ever growing demand for detecting heavy metal with a rapid, sensitive and accurate analytical method.

2. Traditional mercury-selective electrodes have been usually developed based on mercury cation. However, the complexes, such as HgCl₃^- and HgCl₄^2-, exist in Cl^–-rich medium, especially in seawater. The complex pretreatments are always needed before detection of Hg²⁺ ion using traditional mercury cation-selective electrodes for converting HgCl₃^- and HgCl₄^2- to Hg²⁺ ion. Here, a simple method for direct detection of mercury in Cl^--rich medium without any pretreatment has been developed based on an anion mercury ion-selective electrode. Results show that the electrode can be successfully applied to directly detect mercury in 0.05 mol/L NaCl solution. The anion-mercury selective electrode exhibits a Nernstian response in the concentration range of 5.0×10^-7-5.0×10^-5 mol/L, and the detection limit is 4.7×10^-7 mol/L.