Electrocatalytic determination of paraquat using a nafion film coated glassy carbon electrode

A nafion film coated glassy carbon electrode (NFGCE) was employed for the determination of paraquat. Paraquat was accumulated onto NFGCE by the cation-exchange feature of nafion at open circuit potential in basic medium followed by cathodic differential pulse voltammetric (CDPV) determination in a medium containing permanganate ions. The sensitivity for the determination of paraquat was improved through the electrocatalytic reduction of permanganate by the reduced paraquat. With 3-min accumulation, the analytical signal versus concentration dependence was linear from 1.0 to 100 ppb with a detection limit of 0.5 ppb. The interference from common metal ions was minimized by addition of ethylenediaminetetraacetate (EDTA) into the sample solution. The use of nafion also improves the resistance to interference from surfactants.