Anodic stripping voltammetric determination of traces and ultratraces of thallium at a graphite microelectrode. Method development and application to environmental waters

A bare graphite microelectrode was used for the anodic stripping voltammetry determination of traces and ultratraces of Tl+ ion in aqueous solutions at pH 3.5, in the presence of a 1×10−3 mol L−1 EDTA solution. The proposed method, validated and tested at ultratrace level in environmental water samples, showed low detection and quantification limits (0.01 and 0.03gL−1, respectively) and excellent capability to determine the analyte also in the presence of a very high excess of interfering ions, i.e. 2200:1 and 10,000:1 (w:w) for Pb2+ and Cd2+, respectively. Furthermore, the wide linearity range, the absence of bias, the low time required for each measurement and the low cost of theinstrumentation needed are additional factors supporting the application of such a method as a screening tool in the direct determination of thallium ionic species in environmental samples.