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 (Hg2+) 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 Hg2+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 × 10-5M at 293 K by the simple potentiometric method. In addition, it has a sensitivity of 4 × 10-7AM-1with a detection limit of 1.33 × 10-7M by the cyclic voltammetry method. Moreover, the sensor is specific to Hg2+ions in the presence of other ions, such as Na+, K+, Mg2+, Ca2+, Co2+, Ni2+, Zn2+, and Pb2+. Furthermore, the most stable response of the sensor to Hg2+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 Hg2+ions.