Affiliation: | aLaboratoire de Chimie Analytique, Faculté des sciences, Université de Yaoundé I, B. P. 812, Yaoundé, Cameroun bLaboratoire de Chimie Physique et Microbiologie pour l’Environnement, UMR 7564, CNRS– Université Henri Poincaré Nancy I, 405 Rue de Vandoeuvre, F-54600 Villers-les-Nancy, France |
Abstract: | This study is devoted to the evaluation of a carbon paste electrode modified by a natural 2:1 phyllosilicate clay functionalized with either amine or thiol groups as a sensor for mercury(II). Functionalization was achieved by grafting the pristine clay via its reaction with 3-aminopropyltriethoxysilane (APTES) or 3-mercaptopropyltrimethoxysilane (MPTMS), respectively. The electroanalytical procedure comprises two steps: the chemical accumulation of the analyte under open-circuit conditions followed by the electrochemical detection of the preconcentrated species using differential pulse anodic stripping voltammetry. The different parameters that govern the two steps (accumulation time, concentration of the analyte, composition of the detection medium, potential and duration of electrolysis) were studied in detail. After optimization, a linear response was obtained in the concentration range from 0.1 to 0.7 μM Hg(II). In these conditions, the detection limits of the method were found to be 8.7 × 10−8 and 6.8 × 10−8 M, respectively, for the amine- and thiol-functionalized clays, on the basis of a signal-to-noise ratio of 3. The effect of potential interference on the determination of Hg(II) by the carbon paste electrode modified with the thiol-functionalized clay was also studied and the applicability of the method to real sample analysis was evaluated. |