Electrochemical and microscopic study of a rotating disk gold-film electrode for voltammetric determination of arsenic (III)

Abstract

This article is dedicated to the fabrication and thorough examination of the properties of a gold-film electrode (AuFE) intended for arsenic (III) determination using square-wave anodic stripping voltammetry (SWASV). The gold-film electrode was prepared ex-situ by potentiostatic electrodeposition of a gold layer onto a rotating glassy carbon electrode (GCE). Various deposition parameters were investigated and optimized, including the concentration of HAuCl4 solution (0.25 – 4 mM), deposition potential (0 – −600 mV), deposition time (120 – 1200 s), and electrode rotation speed (600 – 1500 rpm). Gold films prepared under different conditions were characterized using cyclic voltammetry (CV), optical microscopy, and scanning electron microscopy (SEM). The influence of AuFE characteristics on the parameters of the As(III) stripping peak was studied. Using the optimized AuFE, sensitivity and detection limit for As(III) of 0.468 μA/μg·L−1 and 1 μg/L, respectively, were achieved. The effects of interfering ions (Fe(III), Mn(II), Pb(II), Cu(II), Sn(IV), Tl(I)) on the As(III) response were investigated. The analytical utility of the optimized AuFE was validated for the quantitative determination of arsenic in tap water and seafood. The proposed procedure provides optimal conditions for the electrochemical preparation of gold-film electrodes aimed at routine arsenic monitoring.