Preconcentration/separation and determination of mercury using microcrystalline phenolphthalein modified by ethyl violet

A novel method was developed for enrichment and separation of trace mercury using phenolphthalein modified by ethyl violet (EV). The effects of different parameters, such as stirring time, various metal ions and salts, and the amounts of phenolphthalein, NH4SCN, and EV on the extraction rate of mercury were studied, to select the experimental conditions. Under optimum conditions, mercury can be adsorbed on the surface of microcrystalline phenolphthalein by the intermolecular action strength. The possible reaction mechanism for the enrichment of mercury was discussed in detail. Hg(II) could be completely separated from Fe(II), Co(II), Ni(II), Mn(II), Cd(II), Cr(III), and AI(III) in the solution. The proposed method has been successfully applied to the determination of trace mercury in industrial wastewater with the recoveries above 99%. The relative standard deviation for five replicate determinations of 0.04 μg·mL−1 of Hg(II) was found to be 1.4%, 1.1%, and 1.2%, respectively. The analytical results were very satisfactory.