Determination of Cu, Pb, Cd, and Zn in river sediment extracts by sequential injection anodic stripping voltammetry with thin mercury film electrode

Determination of Cu, Pb, Cd and Zn was performed in sediment extracts obtai ned according to the three steps sequential extraction procedure proposed b y the European Community Standards, Measurements and Testing Program. The m etal content was determined by anodic stripping voltammetry with a thin mer cury film electrode controlled by a sequential injection (SIA) system. The proposed method improved the reproducibility of conventional anodic strippi ng voltammetry, as well as the sample throughput, allowing analysis of 30 t o 45 samples per hour. The influence of flow rate and sample volume was stu died to achieve an adequate sensitivity for the leachate studied. No interf erences due to adsorption of organic matter, colloids, or complexes with sl ow rate of dissociation were observed. The intermetallic formation of Cu-Zn was avoided by forming the mercury film in presence of Ga(III) ions in the SIA system, resulting in low consumption of reagent in comparison to flow injection or continuous flow systems. Results were in good agreement with t hose obtained by Induced Coupled Plasma - Atomic Emission Spectroscopy (ICP - AES).