Dioctylsulfosuccinate Functionalized NiAl-Layered Double Hydroxide for Sensitive Fenuron Electroanalysis Using a Carbon Paste Electrode.

Environmental pollution resulting from the use of pesticides such as fenuron poses significant health risks due to the carcinogenic and teratogenic properties of these compounds. There is an urgent need to develop rapid and cost-effective detection methods for quantifying fenuron. In this study, an inorganic-organic composite material was obtained by intercalating sodium dioctylsulfosuccinate (DSS) within the interlayer space of a nickel-aluminum-layered double hydroxide (NiAl-LDH). The pristine and modified LDHs (NiAl-LDH) were characterized using Fourier transform infrared, X-ray diffraction, and thermogravimetric analysis, confirming the successful intercalation of DSS in the mineral structure. The modified LDH was used to elaborate a sensor for detecting fenuron herbicide via differential pulse voltammetry (DPV) employing a carbon paste electrode (CPE). The electrochemical procedure for fenuron analysis consisted of immersing the working electrode in an electrolytic solution containing the appropriate amount of fenuron, followed by voltammetry detection without any preconcentration step. Compared to CPE modified by pristine LDH, the peak current obtained on the organo-LDH-modified CPE was twice as high. The increase in the fenuron signal was attributed to the high organophilic feature of this composite material induced by DSS modification. To optimize the sensitivity of the organo-LDH modified electrode, the effects of several experimental parameters such as pH of the medium and proportion of the modifier in the paste on the stripping response were examined. Linear calibration curves were obtained for the fenuron concentrations ranging from 0.5 × 10^-6 to 1 × 10^-6 mol.L^-1 and 1 × 10^-6 to 5 × 10^-6 mol.L^-1. The limit of detection (LOD) calculated on the basis of a signal-to-noise ratio of 3 was found to be 1.8 × 10^-8 mol.L^-1 for the low concentration range with a limit of quantification (LOQ) which was 6 × 10^-8 mol.L^-1. Furthermore, the interference effect of several inorganic ions and other pesticides potentially affecting fenuron stripping was explored, and the method's applicability was confirmed by determining fenuron levels in a river sample taken from down-town Yaoundé.