Voltammetric sensing of dinitrophenolic herbicide dinoterb on cathodically pretreated boron-doped diamond electrode in the presence of cationic surfactant

The present work describes the first anodic voltammetric investigation of dinitrophenolic herbicide dinoterb (DTB). For this purpose a commercially available boron-doped diamond electrode pretreated cathodically was applied. At first, the electrochemical properties based both on the oxidation and on the reduction of DTB were investigated by the means of cyclic voltammetry. To develop a voltammetric method for the determination of DTB, the anodic response corresponding to the oxidation of the phenolic moiety in the molecule was selected which was irreversible and exhibited adsorption controlled. A systematic study of various experimental conditions, such as electrode pretreatment, pH, nature of the supporting electrolytes, accumulation variables, and surfactant on the adsorptive stripping response, were examined by using square-wave voltammetry. An oxidation signal at around +1.22 V in Britton-Robinson buffer at pH 7.0 containing 5 x 10(-5) mol L-1 cetyltrimethylammonium bromide (cationic surfactant) allowed to the adsorptive stripping voltammetric determination of DTB (after 30 s accumulation step at open-circuit condition). The process could be used in the concentration range from 0.0075 to 0.75 mu g mL(-1) (3.12 x 10(-8)-3.12 x 10(-6) mol L-1) with a detection limit equal to 0.0022 mu g mL(-1) (9.16 x 10(-9) mol L-1). The feasibility of developed methodology was tested to the analysis of the spiked samples of river water and soil matrices with the satisfactory recoveries.