Electrochemical studies and square wave stripping voltammetry of five common pesticides on poly 3,4-ethylenedioxythiophene modified wall-jet electrode

The cyclic voltammetric behavior of five common pesticides such as dicofol (DCF), cypermethrin (CYP). monocrotophos (MCP). chlorpyrifos (CPF) and phosalone (PAS) was investigated at a poly 3,4-ethylenedioxythiophene modified glassy carbon electrode (PEDOT/GCE). A method was developed for the detection and determination of these pesticides in trace level flowing stream, based on their redox behavior. The square wave stripping voltammetric principle was used to analyze the selected pesticides on PEDOT/GCE. Varying the accumulation potential and accumulation time, the best accumulation conditions were found out. Effects of initial scan potential, square wave pulse amplitude, step potential and frequency were examined for the optimization of stripping conditions. The peak current responses of analyte under optimum conditions were correlated over flow rate by using wall-jet PEDOT/GCE assembly. The calibration plots were linear over the pesticide's concentration range 0.10-72.60 mug 1(-1) for DCF, 0.41-198.24 mug 1(-1) for CYP, 0.22-220.95 mug 1(-1) for MCP, 0.35-259.69 mug 1(-1) for CPF and 1.07-141.46 mug 1(-1) for PAS. The limit of detection was obtained between <0.09 and <1.0 mug 1(-1) for five pesticides. It is low enough for trace pesticide determination in real samples. This method is applied for the determination of the five pesticides in soil samples. The recovery values obtained in spiked soil samples are 95.4 +/- 5.4% for DCF, 93.7 +/- 4.2% for CYP, 85.3 +/- 8.4% for MCP, 94.6 +/- 6.6% for CPF and 93.5 +/- 4.9% for PAS. (C) 2004 Elsevier B.V. All rights reserved.