Square-wave stripping voltammetric determination of some organic pollutants using modified electrodes

A glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNT) and polymer/MWCNT composite was used to study the voltammetric behaviour of three common insecticides namely cypermethrin (CYP), deltamethrin (DEL) and fenvalerate (FEN). The modified electrode surface was characterised by scanning electron microscopy (SEM). The voltammograms of the above mentioned pollutants were studied in the pH range 1-13. Influence of scan rate (nu) was also studied. One well-defined reduction peak was observed for all the said insecticides at pH 13. A systematic study of the experimental parameters such as accumulation potential, accumulation time, initial scan potential, amplitude and frequency that affect the square-wave stripping voltammetric response was carried out and maximum peak current conditions were optimised. Under optimum conditions, stripping voltammetric procedure was developed for the determination of above-mentioned insecticides in conventional and real samples. Calibration plots were derived and the lower limit of determination was found. Sensing of polypyrrole/MWCNT/GCE well among the three electrode systems and the limit of detection (LOD) was found to be 1.17, 3.8 and 1.62 mu g L-1 for CYP, DEL and FEN, respectively. The percentage of relative standard deviation was also found.