Small-size sensors for the in-field stripping voltammetric analysis of water

Abstract

Sensors based on thick-film graphite and screen-printed electrodes open up a new era in stripping voltammetry. The increasing application of the stripping analysis in laboratory, field, and on-line variants is expected in the near future. The use of modified thick-film graphite and screen-printed electrodes allows solving main problems of the method: toxicity of mercury and mechanical regeneration of the solid electrode surface. However, one of the problems with the stripping voltammetric method, namely the interference of organic compounds, cannot be solved without sample pretreatment. New four-electrode sensors based on thick-film graphite and screen-printed carbon electrodes for analysis of natural and waste waters are described. The analysis is performed in three steps: sample pretreatment, accumulation of the analyte on the electrode surface, and measurement. The measuring cells have a small volume (e.g., 0.2–0.8 ml) sufficient for uniform mixing of the test solution and introduction (if required) of standard additions. A solid electrolyte can be placed in the cell. The sensors were used for determination of Cu, Pb, and Cd concentrations. The detection limit is n × 10⁻⁷ g l⁻¹. Some results of the analysis of model solutions, river and waste waters with the use of the standard addition method or calibration curves are given. © 2002 Wiley Periodicals, Inc. Field Analyt Chem Technol 5: 260–271, 2001; DOI 10.1002/fact.10006