Poly (Amino-Naphthalene Sulfonic Acid) As A Low Cost Electrode Modifier For Electrochemical Sensing, Reaction Kinetics And Rate Constant Study Of Dopamine.

Abstract

Electrochemical methods are a class of techniques in chemistry which study an analyte by measuring the potential and/or current in an electrochemical cell containing the analyte. It is an attractive alternative for sensing owing to its advantages of sensitivity, simplicity, low cost, and easy miniaturization. Various materials for modification on the electrode surfaces have been widely utilized to enhance sensitivity and chemical specificity of electrochemical sensors. The aim of this work is to develop a sensitive analytical method for determination of Dopamine (DA) at poly amino-naphthalene sulfonic acid modified glassy carbon electrode (poly (ANSA)/GCE). Poly(ANSA)/GCE is prepared by electrochemical polymerization of amino-naphthalene sulfonic acid (ANSA) by successive potential scanning between -0.8 and +1.8 V at 0.1 Vs−1 for 12 scans in 0.1 M HNO3 solution at GCE using cyclic voltammetry (CV). The electrochemical active surface areas of bare and modified electrode in [Fe (CN) 6]-3/-4 were 0.07cm2 and 0.11cm2, respectively. These results indicated that the modification of GCE with poly (ANSA) results high surface area. The oxidation of DA was examined at both bare GCE and poly (ANSA)/GCE. Poly (ANSA)/GCE exhibited higher oxidation current than bare GCE. The higher oxidation current at poly (ANSA)/GCE attributed to the higher electroactive surface area and the presence of amino and sulfonic groups in its structure that can facilitate electron transfer processes. Common electrochemical parameters have been optimized for better electroanalytical performance of poly ANSA/GCE. It was calculated that the rate constant (K) and diffusion coefficient (D) of DA were 4.4×103 M−1s−1 and 8.7 × 10−6 cm2 s−1, respectively, at poly (ANSA)/GCE. A detection limit and a dynamic working linear range of DA at poly-ANSA/GCE were 0.089 μM and 0.5 μM - 100 μM, respectively which was studied using linear sweep voltammetry (LSV). For practical applicability poly (ANSA)/GCE was evaluated by detecting DA in DA injection sample. Hence, a percentage recovery in the range of 94.1 - 102.4% was obtained which it can be a good candidate for the practical useability of the proposed electrochemical sensor for DA detection. The poly (ANSA)/GCE additionally displays good repeatability and reproducibility and satisfactory selectivity.