Electrochemical Determination of Arsenic Using Silver Nanoparticles

In the present work, silver colloid was produced by chemical reduction of silver salt (silver nitrate) using citrates in aqueous solution. UV-Vis spectrophotometry indicated the formation of nanoparticles. The surface plasmon resonance peak in absorption spectra of the silver colloidal solution showed an absorption maximum at 435 nm. The dynamic light scattering and zeta potential measurements showed that the size and the zeta potential of the synthesized nanoparticles were about 98 nm and -50 mV respectively. The nanoparticles have been used to modify the gold electrode for use as a potential electrochemical sensor for the analysis of arsenic in aqueous solution. The cyclic voltammogram recorded using gold electrode modified with AgNPs depicted a well-defined reduction peak of arsenic compared to bare gold electrode. The enhancement of the signal is essentially due to the large surface area attributed to silver nanoparticles. Linear sweep voltammetry has been used to optimize the analytical conditions of arsenic in aqueous solution: it came out that the detection of arsenic in 0.1 M HNO3 was optimal while the electrode was conditioned at -0.6 v during 300 s. Under these optimum conditions, a calibration curve was plotted in the concentration range of 0.05 mu M to 0.2 mu M and the detection limit was estimated at 1.38x10(-8) M, calculated from a ratio signal/noise 3.