Stripping voltammetric analysis of mercury ions at nitrogen-doped reduced graphene oxide modified electrode

Abstract Selective and sensitive monitoring of toxic heavy metals is prerequisite to the curb of water contamination. Herein, we present a differential pulse anodic stripping voltammetric (DPASV) method for the determination of mercury in water samples with a glassy carbon electrode (GCE) modified with nitrogen-doped reduced graphene (NRGO). Through thermal treatment of graphene oxide (GO) in NH3 atmosphere, nitrogen atoms can be facilely doped into the hexagonal lattice of graphene to produce NRGO. The NRGO modified GCE (abbreviated as NRGO/GCE) shows an impressively favorable electron transfer activity and a high stripping voltammetric response for mercury compared to that of reduced graphene oxide (RGO) modified electrode. Not only does the NRGO/GCE show an extraordinary low detection limit of 0.58 nM, it also demonstrates a wide linear concentration range from 1 nM to 800 nM and a high sensitivity of 2.69 μA/μM. Due to the excellent selectivity of the NRGO/GCE to mercury, the interference from other heavy metals such as Fe(III), Co(II), Ni(II), Cu(II), Mn(II), Cd(II), Al(III), Ca(II), and Pb(II) were almost negligible. Those outstanding features guarantee the proposed anodic stripping voltammetric method highly applicable to the assay of mercury ions in real water samples, which is validated by the conventional atomic fluorescence spectrometry.