An Electrochemical Approach to As(V) Determination via an Interaction with Alizarin Red S in Aqueous Medium

Abstract

Electrochemically inactive As(V) was detected by estimating the interactions between Alizarin Red S (ARS) and ions in aqueous medium. From the cyclic voltammetry, it was confirmed that the addition of As(V) reduces the diffusion coefficient of the ARS molecule towards the electrode surface. The experimental results revealed that the diffusion coefficient of ARS was 1.476 × 10 −5 cm 2 /s which decreased to 1.02 × 10 −5 cm 2 /s in the presence of ions in the solution. Measurements of electrochemical impedance spectroscopy (EIS) were also carried out, and an upward pattern of charge transfer resistance (R ct ) was found with an increase in As(V) concentration. The EIS technique gave a linear relationship in terms of R ct vs. As(V) concentration. Hence, it was concluded that this technique could be utilized in the electrochemical detection of As(V). The developed method for the detection of As(V) has exhibited excellent sensitivity (74 Ω/μM), low detection limit (14.2 ± 0.1 ppb at S/N of 3), and remarkable repeatability.