title: Cathodic adsorptive stripping voltammetric behaviour of guanine in the presence of copper at the static mercury drop electrode.
abstract: The cathodic adsorptive electrochemical behavior of guanine in the presence of some metal ions at the static mercury drop electrode was investigated. A 1.0x10(-3) mol l(-1) NaOH or a 2.0x10(-2) mol l(-1) Hepes buffer at pH 8.0 solutions were used as supporting electrolytes. The reduction peak potential for guanine was found to be around -0.15 V, which is very close to the mercury reduction wave. A new peak appears at -0.60 V in the presence of copper or at -1.05 V in the presence of zinc. A square wave voltammetric procedure for electroanalytical determination of guanine in 2.0x10(-2) mol l(-1) Hepes buffer at pH 8.0 containing 1.6x10(-5) mol l(-1)of copper ions, was developed. An accumulation potential of -0.15 V during 270 s for the prior adsorption of guanine at the electrode surface was used. The response of the system was found to be linear in the range of guanine concentration from 6.62x10(-8) to 1.32x10(-7) mol l(-1) and the detection limit was 7.0x10(-9) mol l(-1). The influence of DNA bases such as adenine, cytosine and thymine was also examined. Cyclic voltammetry was used to characterize the interfacial and redox mechanism.
authors.affiliation: Departament of Chemistry, Pontificia Universidade Católica, Rua Marquês de São Vicente, 225, CEP 22453-900 Rio de Janeiro, Brazil.
authors.forename: Percio A M
authors.initials: PA
authors.lastname: Farias
authors.forename: Angela de Luca Rebello
authors.initials: Ade L
authors.lastname: Wagener
authors.forename: Margarida Bethlem R
authors.initials: MB
authors.lastname: Bastos
authors.forename: Adriana Tabet da
authors.initials: AT
authors.lastname: Silva
authors.forename: Arnaldo Aguiar
authors.initials: AA
authors.lastname: Castro