Speciation analysis of inorganic arsenic in river water by Amberlite IRA 910 resin immobilized in a polyacrylamide gel as a selective binding agent for As(v) in diffusive gradient thin film technique

Abstract

In this study, a method is proposed for the selective retention of As(V) using diffusive gradient in thin film (DGT) samplers containing a strongly basic anion exchange resin (Amberlite IRA 910) supported on a polyacrylamide gel. In addition, the total arsenic content is determined by ferrihydrite gel discs. Subsequently, the concentration of As(III) was obtained by determining the difference between the total As and As(V). DGT experiments showed linear accumulation of As(V) (up to 280 ng) until a deployment time of 8 h deployment (R² > 0.99). The retention of As(V) was appropriate (97.9–112.3%) between pH 5 and 9. For a solution with an ionic strength ranging from 0.001 to 0.05 mol L⁻¹, the As(V) uptake ranged from 90–120%. The proposed method was applied for the speciation of arsenic in river water. For the analysis of spiked samples collected at the Furnas stream, the recoveries of total arsenic content ranged between 103.9% and 118.8%. However, the recoveries of As(III) and As(V) were 43.3–75.2% and 147.3–153.4%, respectively. These differences were probably because of the oxidation of As(III) to As(V) during deployments. For spiked samples collected at the Ribeirão Claro, the recoveries of dissolved As(III), As(V) and As(T) were 103.1%, 108.0% and 106.3%, respectively. Thus, the DGT technique with Amberlite IRA 910 resin as the binding phase can be employed for the in situ redox speciation of inorganic arsenic.