Amperometric determination of diazinon by gold nanorods/ds-DNA/graphene oxide sandwich-modified electrode

Diazinon (DZ) is an organophosphorus pesticide which is used as an insecticide. Because of its harmful effects, finding a sensitive method to determination of DZ is important. So, in this study, a chemically modified electrode by graphene oxide (GO), functionalized double-strand DNA (ds-DNA) and gold nanorods (GNRs) was used. Interaction between oxygenated groups of GO and GNRs with amine-thiol groups of ds-DNA was used to construct a sandwich-modified electrode named GNRs/ds-DNA/GO/GCE. Characterization of synthesized GNRs and GO was done by transmission electron microscopy and scanning electron microscopy. To finding the effects of modifiers on DZ detection, cyclic voltammetry, and electrochemical impedance spectroscopy were used in each modification steps. The pH and scan rate were optimized at 6.0 and 0.1 V s−1, respectively. Dynamic range of GNRs/ds-DNA/GO/GCE in DZ determination was studied by amperometry with the concentration linear range of 1.9 × 10−6 to 5.6 × 10−5 mol L−1 and detection limit of 1.9 × 10−7 mol L−1. Finally, the application of modified electrode was evaluated on two polluted river water samples with 98.5 to 101% recovery.