Analysis of mercury in wastewater and canned tuna fish samples using carbon paste electrode modified by functionalized high ordered nanoporous SiO2

A carbon paste electrode for hg(ii) ion based on nanoporous silica was prepared. a potentiometric sensor is reported for the mercury(ii) detection, using substituted thiourea-functionalized high ordered nanoporous sio2 of lus-1 (tu-lus-1) as sensitive materials. the carbon paste electrodes modified with tu-lus-1 exhibited high sensitivity for the potentiometric determination of mercury(ii) ions. the electrodes with tu-lus-1 proportion of 10.0 %m/m demonstrated very stable potentials. calibration plots with nernstian slopes for the mercury cations were observed, 28.4 (±1.0) mv decade-1, over a wide linear concentration range (1.0 ×10-7 to 1.0 ×10-1 m). the electrode exhibited a detection limit of 7.0 ×10-8 m. moreover, the selectivity coefficients, measured by the match potential method, were investigated. the potentiometric detection described in this work is shown to have advantages in response time (ca. 35 s), good long term stability (more than 9 months), terms of low cost, and sensitivity. the method was satisfactory and was used to monitor the mercury ion concentration in waste water and fish tuna samples.