The electrochemical behavior of meso-tetrakis(4-sulfonatophenyl) porphyrin tetrasodium salt (TPPS4) was investigated in aqueous media of BR buffer in pH range 2-12. Modern electroanalytical methods, i.e DC tast polarography (DCTP) and differential pulse polarography (both at a dropping mercury electrode), differential pulse voltammetry, adsorptive stripping voltammetry, and cyclic voltammetry (all at a hanging mercury drop electrode) were used for this purpose. TPPS4 gives three cathodic signals for pH 2 - 12, first of them corresponding to a two electron quasireversible process. From these signals, the first two are suitable for the determination of TPPS4 using both polarographic methods with limit of determination about 2 10-6 mol L-1 in BR buffer, pH 10. At concentration higher than 3 10-6 mol L-1, the calibration curve of the first signal deviates from the linear course due to formation of aggregates of TPPS4 in solution. The lowest limit of determination, 5.1 10-7 mol L-1 was achieved by AdSV due to strong adsorption of TPPS4 at the electrode surface. However, for concentrations higher than 1 10-6 mol L-1, the strong adsorption prevents the use of HMDE for voltammetric measurements conducted at low scan rates due to deformation of voltammetric curves and nonlinearity of calibration dependences. On the other hand, at higher scan rates used in CV the linear dynamic range for voltammetric determination of TPPS4 is 4 10-7 - 1 10-5 mol L-1.
|Журнал||International Journal of Electrochemical Science|
|Состояние||Опубликовано - 1 дек 2007|
|Опубликовано для внешнего пользования||Да|
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