β-Cyclodextrins incorporated multi-walled carbon nanotubes modified electrode for the voltammetric determination of the pesticide dichlorophen.

In this work, a glassy carbon electrode modified with β-cyclodextrins and multi-walled carbon nanotubes (β-CDs/MWCNTs/GCE) was constructed and applied for the square-wave adsorptive stripping voltammetric (SWAdSV) determination of the pesticide dichlorophen (Dcp). For the first time, this compound was electrochemically investigated. The voltammetric measurements were conducted in phosphate buffer (PBS) at pH 6.5 as a supporting electrolyte, and SWAdSV technique parameters were optimized. A linear calibration curve in the wide concentration range from 5.0 × 10-8 molL-1 to 2.9 × 10-6 molL-1 was obtained. Excellent analytical performance in terms of limit of detection (LOD) of 1.4 × 10-8 molL-1 was achieved. The utility of the proposed method was verified by the quantitative analysis of Dcp in Pilica River water samples with satisfactory results. The characterization of modified electrodes was conducted by means of atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Moreover, in this work, the dissociation constants (pKa ) of Dcp using potentiometric pH titration were estimated. The stoichiometry of the Dcp-β-CDs inclusion complex formed in solution was determined by proton nuclear magnetic resonance (1 H NMR) spectroscopy, and a binding constant (β2 ) was estimated from NMR titration studies.