A High-Sensitivity Potentiometric Mercuric Ion Sensor Based on m-Toluidine Films

A sensor of m-toluidine polymer film coated platinum electrode was fabricated by the electropolymerization using cyclic voltammetry technique for the detection of mercury ions (Hg 2+ ) in aqueous solution. This paper was carried out using the simple potentiometric method and confirmed by a cyclic voltammetry technique. The effects of the polymer film thickness and pH of Hg 2+ solutions on the response of the sensor were studied. Moreover, the stability, sensitivity, and selectivity of the m-toluidine sensor were investigated. The optimum thickness of the polymer film was obtained after ten cyclic voltammetric runs. This film has a Nernstian response slope of 29.19 mV/decade with a detection limit of 3.54 × 10 -5 M at 293 K by the simple potentiometric method. In addition, it has a sensitivity of 4 × 10 -7 AM -1 with a detection limit of 1.33 × 10 -7 M by the cyclic voltammetry method. Moreover, the sensor is specific to Hg 2+ ions in the presence of other ions, such as Na + , K + , Mg 2+ , Ca 2+ , Co 2+ , Ni 2+ , Zn 2+ , and Pb 2+ . Furthermore, the most stable response of the sensor to Hg 2+ ions in the solution of pH ranged from 4 to 6.4 for a lifetime of about eleven weeks. Moreover, the sensor was applied for detection of four natural samples: tap water; underground water; first distillate water; and another sample wasted with Hg 2+ ions.