Potentiometric detection of mercury(II) ions using a carbon paste electrode modified with substituted thiourea-functionalized highly ordered nanoporous silica.

A potentiometric sensor is reported for the mercury(II) detection, which uses substituted thiourea-functionalized nanoporous silica (FTU-LUS-1) as the sensitive material. Substituted thiourea (FTU) and FTU-LUS-1 were first prepared and then characterized by 1H NMR, 19F NMR, 13C NMR, FTIR, XRD, TG and CNS elemental analysis. The electrodes with FTU-LUS-1 proportion of 10.0 wt% demonstrated very stable potentials. The prepared electrodes exhibit a Nernstian slope of 28.4 +/- 1.0 mV decade(-1) for mercury(II) ion over a wide concentration range of 1.0 x 10(-7) to 1.0 x 10(-1) mol dm(-3). The electrode exhibited a detection limit of 7.0 x 10(-8) mol dm(-3). Moreover, the selectivity coefficient, response time, performance, sensitivity and stability of the modified electrode were investigated. The electrode presented a response time of about 35 s, a high performance and sensitivity in a wide range of cation activities as well as good long term stability (more than 9 months). The method was satisfactory and could also be used to monitor the mercury(II) ion concentration in waste water and fish samples.

9-(2,3-Dichloro-phen-yl)-4a-hydr-oxy-3,3,6,6-tetra-methyl-4,4a,5,6,9,9a-hexa-hydro-3H-xanthene-1,8(2H,7H)-dione.

Mol-ecules of the title compound, C(23)H(26)Cl(2)O(4), are linked by hydrogen bonds between the hydroxyl O atom and the carbonyl O atom of a neighboring mol-ecule. The central hydropyran and fused cyclohexanone rings adopt half-chair conformations, while the fused hydroxycyclohexanone ring adopts a chair conformation.