Square wave anodic stripping voltammetric determination of Cd2+ and Pb2+ at bismuth-film electrode modified with electroreduced graphene oxide-supported thiolated thionine

Graphene oxide (GO)–thionine (TH) nanocomposite was prepared by π–π stacking. The nanocomposite was cast-coated on a glassy carbon electrode (GCE) to prepare an electroreduced GO (ERGO)–TH/GCE, then 2-mercaptoethanesulfonate (MES) was covalently tethered to ERGO–TH by potentiostatic anodization to form an ERGO–TH–MES/GCE. The thiolation reaction was monitored by electrochemical quartz crystal microbalance (EQCM). Square wave anodic stripping voltammetry (SWASV) was used to determine Cd2+ and Pb2+ at the ERGO–TH–MES/GCE further modified with Nafion and Bi. Under the optimal conditions, the linear calibration curves for Cd2+ and Pb2+ are from 1 to 40 μg L−1, with limits of detection (S/N=3) of 0.1 μg L−1 for Cd2+ and 0.05 μg L−1 for Pb2+, respectively. The electrode was used for the simultaneous analysis of Cd2+ and Pb2+ in water samples with satisfactory recovery.