Voltammetric Determination of Dialifos in Soils with a Mercury Film Ultramicroelectrode

Abstract

An extraction‐adsorptive stripping voltammetric procedure for the determination of the pesticide dialifos in soil samples using microwave‐assisted solvent extraction and a mercury film ultramicroelectrode was developed. The method is based on the use of hexane‐acetone solvent (1:1, v/v) and on controlled adsorptive accumulation of the insecticide at the potential of −0.10 V (versus Ag/AgCl) in the presence of Britton‐Robinson buffer (pH 2.0). Soil sample extracts were analyzed directly after drying and redissolution with the supporting electrolyte, but without other pre‐treatment. The limit of detection obtained for a 10 sec collection time was 2.0×10⁻⁸ mol L⁻¹. Recovery experiments for the global procedure, at the 0.100 µg g⁻¹ level, gave satisfactory average and standard deviation results for the two different soils tested.

Keywords:

• Dialifos
• mercury film ultramicroelectrode
• microwave‐assisted solvent extraction
• soils

The authors thank the Fundação para a Ciência e a Tecnologia for financial support through project POCTI/AGR/44491/2002 (co‐financed by FEDER). Oriza Tavares is grateful to POCTI for her fellowship.