Platinized agarose microspheres as a new modifier in graphite paste electrodes for the electrochemical determination...

In the environment, 4-aminophenol (4-AP) is present as a highly toxic compound and water pollutant. In this study, platinized agarose microspheres (PtAM) were used for the first time, for the preparation of a novel, modified graphite paste electrode (GPE/PtAM) for the electrochemical determination of 4-AP. PtAM was characterized using transmission electron microscopy, field emission scanning electron microscopy and energy dispersive X-ray analysis. The electrochemical response characteristics of GPE/PtAM towards 4-AP were investigated via electrochemical impedance spectroscopy, cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The value of the charge transfer resistance obtained for GPE/PtAM was 27.3 Ω. Microscopic surface areas and the surface concentration of the electroactive species for GPE/PtAM were calculated to be 0.077 cm² and 1.13 × 10^-3 mol cm^-2, respectively. The electron transfer coefficient, diffusion coefficient and standard heterogeneous rate constants of 4-AP were calculated as 0.274, 4.56 × 10^-4 cm² s^-1, and 3.32 × 10^-1 cm s^-1, respectively. The influence of pH on the oxidation of 4-AP was investigated and a pH value of 2.0 (using a phosphate buffer solution) was selected as the optimum pH. Under optimum conditions, the calibration was linear between 0.8 and 87 μM with a detection limit of 45 nM. Moreover, GPE/PtAM was applied to determine the concentrations of 4-AP in water samples with satisfactory results.