title: Voltammetric Detection of Urea on an Ag-Modified Zeolite-Expanded Graphite-Epoxy Composite Electrode.
abstract: In this paper, a modified expanded graphite composite electrode based on natural zeolitic volcanic tuff modified with silver (EG-Ag-Z-Epoxy) was developed. Cyclic voltammetry measurements revealed a reasonably fast electron transfer and a good stability of the electrode in 0.1 M NaOH supporting electrolyte. This modified electrode exhibited moderate electrocatalytic effect towards urea oxidation, allowing its determination in aqueous solution. The linear dependence of the current versus urea concentration was reached using square-wave voltammetry in the concentrations range of urea between 0.2 to 1.4 mM, with a relatively low limit of detection of 0.05 mM. A moderate enhancement of electroanalytical sensitivity for the determination of urea at EG-Ag-Z-Epoxy electrode was reached by applying a chemical preconcentration step prior to voltammetric/amperometric quantification.
authors.affiliation: "Politehnica" University of Timisoara, P-ta Victoriei, nr.2, 300006, Timisoara, Romania. florica.manea@chim.upt.ro.
authors.forename: Florica
authors.initials: F
authors.lastname: Manea
authors.affiliation: "Politehnica" University of Timisoara, P-ta Victoriei, nr.2, 300006, Timisoara, Romania. aniela.pop@chim.upt.ro.
authors.forename: Aniela
authors.initials: A
authors.lastname: Pop
authors.affiliation: West University of Timisoara, Laboratory of Electrochemistry, Str. Pestalozzi nr.16, 300115 Timisoara, Romania. radovan@cbg.uvt.ro.
authors.forename: Ciprian
authors.initials: C
authors.lastname: Radovan
authors.affiliation: Delft University of Technology, 2600 GA Delft, The Netherlands. p.g.malchev@tudelft.nl.
authors.forename: Plamen
authors.initials: P
authors.lastname: Malchev
authors.affiliation: "Politehnica" University of Timisoara, P-ta Victoriei, nr.2, 300006, Timisoara, Romania. adriana.bebeselea@chim.upt.ro.
authors.forename: Adriana
authors.initials: A
authors.lastname: Bebeselea
authors.affiliation: "Politehnica" University of Timisoara, P-ta Victoriei, nr.2, 300006, Timisoara, Romania. georgeta.burtica@chim.upt.ro.
authors.forename: Georgeta
authors.initials: G
authors.lastname: Burtica
authors.affiliation: Delft University of Technology, 2600 GA Delft, The Netherlands. s.j.picken@tudelft.nl.
authors.forename: Stephen
authors.initials: S
authors.lastname: Picken
authors.affiliation: Delft University of Technology, 2600 GA Delft, The Netherlands. j.schoonman@tudelft.nl.
authors.forename: Joop
authors.initials: J
authors.lastname: Schoonman
keywords: Urea determination; electrocatalytic effect; expanded graphite-Ag-zeolite-epoxy composite electrode