title: A disposable chronocoulometric sensor for heavy metal ions using a diaminoterthiophene-modified electrode doped with graphene oxide.
abstract: The rapid simultaneous determination of cadmium, lead, copper, and mercury ions is performed by employing a disposable sensor modified with graphene oxide (GO) doped diaminoterthiophene (GO/DTT) for chronocoulometry (CC). The performances of CC with and without pre-deposition in two opposite potential step directions were compared with square wave anodic stripping voltammetry (SWASV) under various conditions. The surface of the GO/DTT modified screen print carbon electrode (SPCE) was characterized by SEM, EDXS, and electrochemical impedance spectroscopy (EIS). Experimental variables that affect the response signal such as the pH, deposition time, type of supporting electrolyte, concentration of DTT, content ratio of GO to DTT, and Nafion content were optimized. Interference effects due to other heavy metal ions were also investigated. The dynamic ranges of SWASV and CC were between 1 ng mL(-1) and 2.5 μg mL(-1) and between 1 ng mL(-1) and 10 μg mL(-1), respectively. The detection limits for Cd(2+), Pb(2+), Cu(2+), Hg(2+) ions were 1.9 ± 0.4 ng mL(-1), 2.8 ± 0.6 ng mL(-1), 0.8 ± 0.2 ng mL(-1), and 2.6 ± 0.9 ng mL(-1) for the CC stripping method; 2.6 ± 0.2 ng mL(-1), 0.5 ± 0.1 ng mL(-1), 1.8 ± 0.3 ng mL(-1), and 3.2 ± 0.3 ng mL(-1) for the CC deposition method; and 7.1 ± 0.9, 1.9 ± 0.3, 0.4 ± 0.1, and 0.7 ± 0.1 ng mL(-1) for SWASV. The reliability of the method for point-of-analysis was evaluated by analyzing a urine standard reference material and some water samples.
authors.affiliation: Department of Chemistry and Institute of BioPhysio Sensor Technology, Pusan National University, Busan 609-735, South Korea.
authors.forename: Seung-Min
authors.initials: SM
authors.lastname: Choi
authors.affiliation: Department of Chemistry and Institute of BioPhysio Sensor Technology, Pusan National University, Busan 609-735, South Korea.
authors.forename: Dong-Min
authors.initials: DM
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Institute of BioPhysio Sensor Technology, Pusan National University, Busan 609-735, South Korea.
authors.forename: Ok-Sang
authors.initials: OS
authors.lastname: Jung
authors.affiliation: Department of Chemistry and Institute of BioPhysio Sensor Technology, Pusan National University, Busan 609-735, South Korea. Electronic address: ybshim@pusan.ac.kr.
authors.forename: Yoon-Bo
authors.initials: YB
authors.lastname: Shim
mesh_terms: D002244:Carbon / Q000737:chemistry; D058266:Dielectric Spectroscopy; D004566:Electrodes; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D019216:Metals, Heavy / Q000032:analysis* / Q000652:urine; D010087:Oxides / Q000737:chemistry; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D007477:Ions; D019216:Metals, Heavy; D010087:Oxides; D013876:Thiophenes; C019101:alpha-terthienyl; D002244:Carbon; D006108:Graphite
keywords: Chemically modified electrode; Chronocoulometric sensor; Diaminoterthiophene; Graphene oxide; Heavy metal ions; Square wave anodic stripping voltammetry