Preparation of GO/Fe3O4@PMDA/AuNPs nanocomposite for simultaneous determination of As3+ and Cu2+ by stripping voltammetry.

One of the critical challenges in the simultaneous determination of As3+ and Cu2+ by stripping voltammetry is the overlapping of their oxidation peaks. Therefore, the engineering of nanostructured sensors in order to uplift their electrochemical performance is a significant issue for the codetection of As3+ and Cu2+. Herein, we modified a glassy carbon electrode with a new nanocomposite based on poly methyldopa along with gold nanoparticles immobilized on the surface of magnetic graphene oxide (GCE/GO/Fe3O4@PMDA/AuNPs) that can determine As3+ and Cu2+ with great sensitivity. Optimization of the measurement conditions by square wave stripping voltammetry (SWSV) caused the oxidation peaks of As3+ and Cu2+ to be distinguished significantly from each other, while the peak currents of As3+ and Cu2+ increased 9-12 fold, respectively, compared to the bare electrode. The proposed electrode exhibits low detection limits (S/N ≥ 3): 0.15 ppb for As3+ and 0.11 ppb for Cu2+. The GCE/GO/Fe3O4@PMDA/AuNPs also has good linearity over a wide concentration range from 5 to 500 ppb for As3+ and 0.5-750 ppb for Cu2+. The good recovery values were obtained for the analysis of As3+ and Cu2+ in pool and drinking water samples.