Examinando por Materia "Stripping voltammetry"
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- PublicaciónSólo datosDevelopment of a novel electrochemical sensor based on cobalt(II) complex useful in the detection of dopamine in presence of ascorbic acid and uric acid(Journal of Electroanalytical Chemistry, 2017-02-01) Nagles, Edgar; Ibarra, Laura; Penagos-Llanos, Johisner; Hurtado, John; García-Beltrán, Olimpo[(Co(bdmpzm)2(NCS)2] (bdmpzm = bis(3,5-dimethylpyrazol-1-yl)methane) was synthesized and combined with single walled carbon nanotubes (SWCNT) and nafion on a screen printed carbon electrode (SPCE). The electrocatalytic activity of modified electrode (Nafion-SWCNT-[Co(bdmpzm)2(NCS)2]/SPCE) was evaluated for dopamine (DA) oxidation. Anodic and cathodic peak were seen to 0.42 V.and0.29 V respectively, showed a much more quasi-reversible process, (∆ V 0.128) compared with the electrode without cobalt complex. The detection limit (3σ/b) for dopamine was 0.095 μmol L− 1. The studies of reproducibility determined as relative standard deviation (RSD) was 2.5%.(n = 5) with four different electrodes. The repeatability were 1.5% (n = 5) The new sensor was used in the quantify DA in human urine with an average recovery between 83.0 and 93.0%.
- PublicaciónSólo datosSimultaneous Determination of Lead and Cadmium by Stripping Voltammetry Using in-situ Mercury Film Glassy Carbon Electrode Coated with Nafion-Macrocyclic Ester(International Journal of Electrochemical Sciences, 2017-07-12) Lara, Jesid; Torres, Juan F.; García-Beltrán, Olimpo; Nagles, Edgar; Hurtado, JohnThis work report a sensitive and selective anodic stripping method for the simultaneous determination of Pb(II) and Cd(II) using (3,10,18,25-tetraoxapentacyclo [25.3.1.112,16.04,9.0 19,24] dotriaconta1(31),4(9),5,7,12(32),13,15,19,21,23,27,29-dodecaene-2,11,17,26-tetrone) macrocyclic ester (L). Anodic peak currents were increased from 1.16 to 31.48 µA for Pb(II) and 0.22 to 6.68 µA for Cd(II) when the in-situ mercury film electrode was modified with nafion and (L). Moreover, potentials separation values for Cd-Pb shift from 150 to 190 mV. Optimal parameters such as: pH; L concentration (CL), mercury concentration (CHg), accumulation potential (EACC) and accumulation time (tACC) were pH 4.0 for Pb(II) and 5.0 for Cd(II) using phosphate buffer solution (PBS), CL 12.0 mmol L -1 , CHg 28.0 mg L-1 , EACC -1.0 V and tACC 60. Detection limits (DoL) were 0.085 and 0.80 µg L-1 for Pb(II) and Cd(II) respectively. The relative standard deviation (RSD) for seven measurements of Pb(II) and Cd(II) 9.0 µg L-1 were of 2.5 and 2.0% respectively. The method was validated by ICP multielement standard solution IX (Merck) containing As, Be, Cd, Cr(VI), Hg, Ni, Pb, Se and Tl 100 mg L1 . Finally, useful of the modified electrode was developed in the analysis of Pb(II) and Cd(II) using tap water samples