José Manuel Olmos

University of Murcia | UM · Departamento de Química Analítica

A nitrate selective electrode was used for real-time in situ potentiometric monitoring of a batch nitrate removal process using activated carbon and ion exchange resin. A plasticized polymeric membrane consisting of polyvinyl chloride, 2-nitrophenyl octyl ether and tridodecyl methyl ammonium chloride was incorporated into an ion-selective electrode...

The present study proposes two unique systems using free radical-induced grafting reactions to combine Ag, chitosan (CS) and gallic acid (GA) into a single particulate nanostructure. GA-grafted-CS (GA-g-CS) was used to reduce Ag+ to Ag0, and producing Ag-GA-g-CSNPs (hybrid NPs I). Also, GA was grafted into CS-AgNPs, to form GA-g-CS AgNPs (hybrid NP...

The electrochemical behaviour of the alkaloids berberine and palmatine at the polarized water/1,2-dichloroethane interface is studied by first time. The interface is supported on the micropores of a PET (polyethylene terephthalate) membrane by using an electrochemical cell employed in previous works. Chronoamperometry and square wave voltammetry ar...

The value of double potential pulse differential techniques for electrochemical studies of dynamic chemical speciation is investigated within the context of liquid|liquid electrochemistry. Then, not only information about the speciation thermodynamics and kinetics is accessible, but also about the species lipophilicity. This provides a comprehensiv...

Ion transfer electrochemistry is a powerful tool for the study of ionic species in solution. In this paper, square wave voltammetry and chronoamperometry are applied for the quantification and characterization of denatonium ion (N-benzyl-2-(2,6-dimethylphenylamino)-N,N-diethyl-2-oxoethanaminium) in water, an important additive present in commercial...

A very general theory is derived for the voltammetry of two polarizable interface (2PI) systems in the presence of an arbitrary number and concentration of transferable species in the two aqueous phases. Analytical equations are derived for the current response in any voltammetric technique, regardless of the charge number and lipophilicity of the...

Non-canonical DNA structures are nucleic acid arrangements that differ from the classical Watson-Crick double helical structure and can be observed in some specific DNA sequences depending on the molecular environment [1]. Good stability and reversible responsiveness makes these secondary structures attractive in the field of nanotechnology and bio...

Two cytosine (C) rich DNA sequences folding in i-motif upon protonation of C at low pH have been immobilized at gold electrodes to study the impact of the electrode|electrolyte interface on the stability of the noncanonical DNA secondary structure. The effects of the molecular composition and environment on the melting and folding of the structures...

Analytical expressions are obtained for the study of the net current and individual fluxes across macro- and micro-liquid|liquid interfaces in series as those found in ion sensing with solvent polymeric membranes and in ion-transfer batteries. The mathematical solutions deduced are applicable to any voltammetric technique independently of the lipop...

A new theory is presented to tackle the study of transfer processes of hydrophilic ions in two polarisable interface systems when the analyte is initially present in both aqueous phases. The treatment is applied to macrointerfaces (linear diffusion) and microholes (highly convergent diffusion), obtaining analytical equations for the current respons...

A simple theoretical approach is presented to study simple and facilitated ion transfer processes at liquid/liquid microinterfaces of the most common geometries: micropipettes, microholes, micropores and microcapillaries. A general and accurate expression is reported for the current-potential response in any voltammetric technique. The analytical s...

The quantitative characterization of inclusion complexes formed in aqueous phase between organic ions and hydrophilic hosts by ion-transfer voltammetry with solvent polymeric membrane ion sensors is studied, both in a theoretical and experimental way. Simple analytical solutions are presented for the determination of the binding constant of the com...

The study of the so-called aqueous complexation-dissociation coupled to transfer (ACDT) mechanism is extended to systems where the ligand species is not neutral and so the charge of the two transferable ions is different (z1 ≠ z2). This has a profound effect on the voltammetric response of the system, which shows a complex behaviour depending on th...

A new transfer mechanism is considered in which two different ionic species of the same charge can be transferred across a soft interface while they interconvert with each other in the original phase through a homogeneous chemical reaction: the aqueous complexation-dissociation coupled to transfer (ACDT) mechanism. This can correspond to a free ion...

Square wave voltammetry (SWV), chronoamperometry and chronocoulometry are exploited to take advantage of their different performance characteristics in the determination, characterization and sensing of the neurotransmitter 2-phenylethylamine (PEA), based on the ion transfer of its protonated form at a solvent polymeric membrane facilitated by dibe...

The value of the electrochemical technique Reverse Pulse Voltammetry (RPV) for the characterization of chemical equilibria in solution is theoretically investigated. For this, the RPV response of the square scheme is studied at spherical and disc electrodes of any size assuming that the chemical reactions are at equilibrium. When the effective diff...

Square wave voltammetry (SWV) at disc and hemispherical microelectrodes is studied when the electroactive species show different diffusivities and/or take part in chemical equilibria in solution, under both transient and steady state conditions. Despite the use of microelectrodes, experiments in pulse techniques such as SWV frequently correspond to...

A rigorous analytical solution is presented for the study of chemical equilibria coupled to reversible electron transfers by means of differential double pulse voltammetry (DDPV) at (hemi)spherical electrodes. Special attention is paid to situations where the chemical processes in solution involve a significant change in the diffusivity of one of t...

The application of voltammetric techniques to the study of chemical speciation and stability is addressed both theoretically and experimentally in this work. In such studies, electrode reactions are coupled to homogeneous chemical equilibria (complexations, protonations, ion associations,…) that can be studied in a simple, economical and accurate w...

A rigorous and simple analytical solution is reported for the square scheme in single pulse techniques at (hemi)spherical electrodes when the electron transfers are reversible and the coupled chemical reactions are at equilibrium. The solution presented imposes no restriction to the values of the diffusion coefficients of the different species, and...