A new simple and inexpensive optical chemical sensor for mercury(II) ion in aqueous solutions is presented. The mercury sensing membrane was prepared by incorporating of triazene ((E)-1-(2-ethoxyphenyl)-3-(4-nitrophenyl) triaze-1-ene) (L) as a suitable ligand for Hg(II) on triacetylcellulose membrane. Spectrophotometric study of complex formation between the triazene ligand L and Hg2+ in dimethyl formamide solution indicated a large stability constant for the mercury ion complex. The membrane responds to mercury ion by changing color reversibly from orange to green in buffer solution at pH 3.0. A linear relationship was observed between the membrane absorbance at 405 nm in a range from 7 to 90 µg mL-1 with a limit of detection of 64 ng mL-1 in aqueous solutions at pH 3.0. The optical sensor was successfully applied to the determination of mercury in spiked water samples.
optical sensor; Hg2+ ion; triazene ((E)-1-(2-ethoxyphenyl)-3-(4-nitrophenyl) triaze-1-ene) ligand
