Determination of aluminum as contaminant in dialysis concentrates by adsorptive cathodic stripping voltammetry

This paper describes a stripping voltammetric method for the determination of aluminum as contaminant in dialysis concentrates. It is based on the adsorptive deposition of the complex Al-1,2-dihydroxyanthraquinone-3-sulfonic acid (DASA) at the hanging mercury drop electrode (HMDE) at -0.9V (versus Ag/AgCl) and its cathodic stripping during the potential scan. The method was optimized concerning the main electrochemical parameters that influence the voltammetric determination in highly saline solutions (sample dilution factor, deposition time and DASA concentration). The linear range for the measurements was from -1 with a detection limit calculated as 0.8μgl^-1 for a deposition time of 15s. Aluminum recoveries between 91.0 and 105.5% for spiked samples of dialysis concentrates proof the accuracy of the proposed voltammetric method. The method allows the rapid aluminum determination at μgl^-1 levels in the presence of Zn(II) as interfering ion, and it was applied to its determination in commercial dialysis concentrates used routinely by hemodialysis centers in Brazil. Aluminum concentrations between 9.0 and 78.7μgl^-1 were determined in five different samples of three kinds of dialysis concentrates.