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 pi-pi 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 anodizadon to form an ERGO-TH-MES/GCE. The thiolation reaction was monitored by electrochemical quartz crystal microbalance (EQCM). Square wave anodic stripping voltammetty (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 I to 40 tg L-1, with limits of detection (S/N=3) of 0.1 mu g L-1 for Cd2+ and 0.05 mu g L-1 for Pb2+, respectively. The electrode was used for the simultaneous analysis of Cd2+ and Pb2+ in water samples with satisfactory recovery. (C) 2014 Elsevier B.V. All rights reserved.