Examinando por Autor "Cuadrado, Carol"
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- PublicaciónSólo datosElectrochemical sensors for dopamine using graphene-cobalt(II) complex modified glassy carbon electrode by adsorptive voltammetry(Analytical and Bioanalytical Electrochemistry, 2016-11-15) Cuadrado, Carol; Ibarra, Laura; Hurtado, John; García-Beltrán, Olimpo; Nagles, Edgar[Co(bdmpzm)2(NCS)2] (bdmpzm=bis(3,5-dimethylpyrazol-1-yl)methane) was dispersed in graphene oxide (GOx). Composite GOx-[Co(bdmpzm)2(NCS)2] was deposited on a glassy carbon electrode (GCE) and reduced at -1.0 by 60 s. The modified electrode rGOx-[Co(bdmpzm)2(NCS)2]/GCE allowed the oxidation for dopamine (DA) at 0.41 V Our results showed reversible and sensitive process, (∆V 0.09 V) compared with the electrode without modified in buffer phosphate solution pH 3.0. The detection limit (3σ/b) for dopamine was 0.11 µmol L-1 and the RSD was 3.0%. The presence of uric acid and ascorbic acid did not interfere with the signal for dopamine.
- PublicaciónSólo datosIn situ-Mercury Film Electrode for Simultaneous Determination of Lead and Cadmium Using Nafion Coated New Coumarin Schiff Base as Chelating-Adsorbent(International Journal of Electrochemical Sciences, 2016-11-10) Nuñez-Dallos, Nelson; Cuadrado, Carol; Hurtado, John; Nagles, Edgar; García-Beltrán, OlimpoReaction of o-phenylenediamine and 8-formyl-7-hydroxycoumarin yield a new coumarin salen ligand, (CSB) which was isolated as orange air-stable solid and characterized by melting point, thermogravimetric analysis (TGA), mass spectra, infrared and NMR (1H, 13C) spectroscopy. New CSB was dispersed in nafion and nafion-CSB composite was deposited on a glassy carbon electrode. The modified electrode nafion-CSB/GCE allowed the formation in-situ of mercury film for detection of Pb (II) and Cd(II) by anodic stripping voltammetry (ASV) in buffer phosphate solution pH 3.0 and 4.0. Optimal conditions were studied (mercury concentration: CHg 40.0 mg L-1 ; CSB concentración; CCSB; 20.0 µmol L-1 ; pH 3.0 and pH 4.0; EACC:-1.1 V and tACC: 80).The detection limit (3σ/b) for Pb (II) Cd (II) were of 0.15 µg L–1 for Pb(II) and Cd(II) at pH 3.0. Moreover, 0.071 and 0.080 µg L–1 for Pb(II) and Cd(II), respectively at pH 4.0, The method was validated using ICP multi-element standard solution IX (Merck) containing As, Be, Cd, Cr(VI), Hg, Ni, Pb, Se and Tl 100 mg L-1 . Finally, river, tap and mineral waters were analyzed.