title: Arsenic(III) detection using electrochemical-chemical-chemical redox cycling at bare indium-tin oxide electrodes.
abstract: Sensitive As(III) detection in ground water is of great importance for evaluating the quality of drinking water. We report a sensitive electrochemical method for As(III) detection based on electrochemical-chemical-chemical (ECC) redox cycling involving Ru(IV) [an oxidized species of Ru(III)(NH3)5NH2(2+)], As(III), and tris(3-carboxyethyl)phosphine (TCEP). Electrochemical oxidation of Ru(III)(NH3)5NH2(2+) formed from Ru(III)(NH3)6(3+) generates Ru(IV), which quickly oxidizes As(III). This electro-mediated oxidation of As(III) produces As(V), which is reduced back to As(III) by TCEP. Electrochemically generated Ru(IV) then reoxidizes As(III), allowing ECC redox cycling to occur at a high rate on bare indium-tin oxide (ITO) electrodes without modifying the surfaces with electrocatalytic materials. Because most interfering metal ions precipitate in a carbonate buffer, water samples are mixed with carbonate buffers prior to electrochemical measurements, rendering the effects of Cu(+), Cu(2+), Fe(2+), Fe(3+), and Pb(2+) insignificant. The detection limit calculated by ECC redox cycling using a chronocoulogram is 1.2 μM, much lower than that obtained using only the electro-mediated oxidation of As(III) (90 μM).
authors.affiliation: Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University, Busan 609-735, Korea. hyang@pusan.ac.kr.
authors.forename: Jinkyo
authors.initials: J
authors.lastname: Jeong
authors.forename: Jagotamoy
authors.initials: J
authors.lastname: Das
authors.forename: Moonjung
authors.initials: M
authors.lastname: Choi
authors.forename: Jinkyung
authors.initials: J
authors.lastname: Jo
authors.forename: Md Abdul
authors.initials: MA
authors.lastname: Aziz
authors.forename: Haesik
authors.initials: H
authors.lastname: Yang
mesh_terms: D001151:Arsenic / Q000032:analysis*; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004566:Electrodes; D010084:Oxidation-Reduction; D017971:Tin Compounds / Q000737:chemistry*
chemical_list: D017971:Tin Compounds; C109984:indium tin oxide; D001151:Arsenic