Mercury(II)-selective polymeric membrane electrode based on the 3-[4-(dimethylamino)phenyl]-5-mercapto-1,5-diphenylpentanone

Abstract A new poly(vinylchloride) (PVC) membrane electrode based on 4-(4- N , N -dimethylphenyl)-2,6-diphenylpyrilium tetrafluoroborate as the ionophore was prepared, which shows a good selectivity for mercury(II) ions. The electrode indicates a good linear response for mercury(II) over a wide concentration range from 1.0 × 10 −8 to 1.0 × 10 −3  M, with a near-Nernstian slope of 34 mV per decade and the detection limit is 1.0 × 10 −8  M. This membrane electrode operates well in the pH range of 2.5–7.0 and can be used for at least 30 days without observing any considerable deviation. Selectivity coefficients of some mono-, di- and trivalent metal ions were also determined. The sensor exhibits high selectivity towards mercury(II), compared with the alkali, alkaline earth and transition metal ions. The electrode was also applied as an indicator electrode for potentiometric titration of mercury(II) ion with I − .