Comparison of voltammetric and AAS methods for As(III) quantification in presence of iron species in model water samples with a low mineral content

Abstract : Voltammetry was adapted to quantify As(III) in model water samples with a low mineral content and compared to the Hydride Generation Atomic Absorption Spectrometry (HG-AAS) method. The specificity lies in the study of the influence of interfering species on the quantification of samples treated by coagulation/flocculation using iron salts. First, a Square Wave Cathodic Stripping Voltammetry method at a Hanging Mercury Drop Electrode (SW-CSV - HMDE) was optimised and compared with the HG-AAS method. Second, the influence of the presence of Fe(II), Fe(III) and As(V) was evaluated. No interferences from As(V) were observed, however for both methods, the As(III) signal decreased by 10% in presence of iron. Standard addition method was thus required to efficiently quantify As(III) in complex matrix and the SW-CSV (limit of quantification = 0.5 µg L−1) method was preferred to the HG-AAS technique to determine low As(III) levels ([As(III)] ≤ 2 µg L−1).