Document Type : Research Paper
The characterization of an optical sensor membrane is described for the determination of Hg2+ ions based on the immobilization of 5, 6 Di methyl -1- ( 4 methyl benzyl) -2- para tolyl-1H-benzimidazole (DMBPTBI) on a triacetylcellulose membrane. The membrane responds to mercury ions by changing color reversibly from orange to red in universal buffer solution at pH 2. Under optimum conditions, the proposed membrane displayed a linear range of 0.1-12 μg mL-1 with a limit of detection of, 0.02 μg mL-1 at a wavelength of 558 nm. The response time of the optode was about 8 -10 min, depending on the concentration of mercury (II) ions. The coefficients of variation (CV) of the sensor response for, 1.0 μg mL-1 of Hg(II) was, 1.8% and the CV between seven membranes was 2.3%. The sensor can readily be regenerated with the ethylene diamine solution. The optode is fully reversible and the selectivity of optode to Hg2+ ions in universal buffer is relatively good as interferences. The proposed optode was applied successfully for the determination of mercury (II) in various samples.