title: Electrosorption of Os(III)-complex at single-wall carbon nanotubes immobilized on a glassy carbon electrode: application to nanomolar detection of bromate, periodate and iodate.
abstract: A simple procedure was developed to prepare a glassy carbon electrode modified with single-wall carbon nanotubes (SWCNTs) and Os(III)-complex. The glassy carbon (GC) electrode modified with CNTs was immersed into Os(III)-complex solution (direct deposition) for a short period of time (60s). 1,4,8,12-Tetraazacyclotetradecane osmium(III) chloride, (Os(III)LCl(2)).ClO(4), irreversibly and strongly adsorbed on SWCNTs immobilized on the surface of GC electrode. Cyclic voltammograms of the Os(III)-complex-incorporated-SWCNTs indicate a pair of well defined and nearly reversible redox couple with surface confined characteristic at wide pH range (1-8). The surface coverage (Gamma) and charge transfer rate constant (k(s)) of the immobilized Os-complex on SWCNTs were 3.07 x 10(-9)molcm(-2), 5.5 (+/-0.2)s(-1), 2.94 x 10(-9)molcm(-2), 7.3 (+/-0.3)s(-1) at buffer solution with pH 2 and 7, respectively, indicate high loading ability of SWCNTs for Os(III) complex and great facilitation of the electron transfer between electroactive redox center and carbon nanotubes immobilized on the electrode surface. Modified electrodes showed higher electrocatalytic activity toward reduction of BrO(3)(-), IO(3)(-) and IO(4)(-) in acidic solutions. The catalytic rate constants for catalytic reduction bromate, periodate and iodate were 3.79 (+/-0.2) x 10(3), 7.32 (+/-0.2) x 10(3) and 1.75 (+/-0.2) x 10(3)M(-1)s(-1), respectively. The hydrodynamic amperometry of rotating modified electrode at constant potential (0.3V) was used for nanomolar detection of selected analytes. Excellent electrochemical reversibility of the redox couple, good reproducibility, high stability, low detection limit, long life time, fast amperometric response time, wide linear concentration range, technical simplicity and possibility of rapid preparation are great advantage of this sensor.
authors.affiliation: Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj, Iran. absalimi@uok.ac.ir
authors.forename: Abdollah
authors.initials: A
authors.lastname: Salimi
authors.forename: Begard
authors.initials: B
authors.lastname: Kavosi
authors.forename: Ali
authors.initials: A
authors.lastname: Babaei
authors.forename: Rahman
authors.initials: R
authors.lastname: Hallaj
mesh_terms: D000327:Adsorption; D001959:Bromates / Q000032:analysis*; D002244:Carbon / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D005898:Glass / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007452:Iodates / Q000032:analysis*; D015394:Molecular Structure; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010504:Periodic Acid / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013499:Surface Properties; D013997:Time Factors
chemical_list: C530492:1,4,8,12-tetraazacyclotetradecane osmium(III) chloride; D001959:Bromates; D007452:Iodates; D037742:Nanotubes, Carbon; D009942:Organometallic Compounds; D010504:Periodic Acid; D002244:Carbon; C009288:metaperiodate