Electrooxidation and determination of etidronate using copper nanoparticles and microparticles-modified carbon paste electrodes

Abstract

O comportamento eletroquímico e a determinação de um bisfosfonato, o etidronato de sódio, em três diferentes eletrodos de cobre: eletrodo de cobre policristalino (CE) e eletrodos de pasta de carbono modificados com micropartículas de cobre (m-CPE) e nanopartículas de cobre (n-CPE) foi investigado. Usando o eletrodo CE, os voltamogramas apresentaram um pico de corrente anódica, enquanto com m-CPE e n-CPE, foram observados dois picos de corrente de oxidação. A densidade de corrente anódica em 610 mV para n-CPE é cinco vezes maior do que para m-CPE. Isto está relacionado ao efeito do tamanho das nanopartículas de cobre. As correntes anódicas foram relacionadas à oxidação eletrocatalítica do etidronato via eletrogeração de espécies ativas de Cu(III) em um mecanismo EC'. Os valores para a constante de velocidade catalítica para o processo de oxidação e o coeficiente de difusão do etidronato foram 8,9 × 103 cm 3 mol -1 s -1 e 1,55 × 10 -6 cm 2 s -1 , respectivamente. Um procedimento sensível e rápido foi desenvolvido para a análise de etidronato, e os parâmetros analíticos correspondentes foram relatados. O etidronato foi determinado com um intervalo linear de 10,57 mmol L -1 e um limite de detecção de 200-2538 mmol L -1 . A exatitude foi checada pela aplicação do teste de recuperação nas amostras. O método amperométrico proposto foi aplicado à análise de comprimidos farmacêuticos comerciais e os resultados apresentaram concordância com os valores de literatura.The electrochemical behavior and determination of a bisphosphonate drug, sodium etidronate, on three different copper-based electrodes: polycrystalline copper electrode (CE) and copper microparticles-(m-CPE) and copper nanoparticles (n-CPE)-modified carbon paste electrodes was investigated. In the voltammograms recorded using CE, one anodic peak was appeared while, both m-CPE and n-CPE represented two anodic oxidation peaks. The anodic current density at 610 mV for n-CPE is >5 times higher that of m-CPE. This was related to the nanosize effect of copper nanoparticles. The anodic currents were related to the electrocatalytic oxidation of etidronate via the electrogenerated active species of Cu(III) in an EC' mechanism. The catalytic rate constant for the oxidation process and the diffusion coefficient of etidronate were obtained as 8.9×103 cm 3 mol -1 s -1 and 1.55×10 -6 cm 2 s -1 , respectively. A sensitive and time-saving sensing procedure was developed for the analysis of etidronate, and the corresponding analytical parameters were reported. Etidronate was determined with a limit of detection of 10.57 mmol L -1 with a linear range of 200-2538 mmol L -1. Accuracy was also checked by recovery test on spiked samples. The proposed amperometric method was applied to the analysis of commercial pharmaceutical tablets and the results were in good agreement with the declared values.

A Nafion Film Cover to Enhance the Analytical Performance of the CuO/Cu Electrochemical Sensor for Determination of Chemical Oxygen Demand

“…This electrochemical process is highly dependent on both the hydroxide concentration and the previous formation of a specific layer of Cu(II) oxide. The participation of Cu(III) species as an electron transfer mediator has been suggested to explain the good performance of Cu electrode in alkaline medium in anodic processes, related to several organic compounds [8,30] in agreement with the following reactions:Cu+ 2OH − ⇄ Cu(OH) 2 + 2e − …”

Differential Pulse Voltammetric Electrochemical Sensor for the Detection of Etidronic Acid in Pharmaceutical Samples by Using rGO-Ag@SiO2/Au PCB

“…EA followed a similar oxidation procedure ( Figure S5 ). Initially, C–P bond breaking occurs via oxidation, which causes the formation of phosphate ions [ 37 , 38 ]. The oxidation process is driven by the participation of 1.5 times more protons than the number of electrons (3:2).…”

A Self-Supported CuO/Cu Nanowire Electrode as Highly Efficient Sensor for COD Measurement

“…Although the electrochemistry of copper and copper-based electrodes in alkaline solutions has been extensively investigated [29,30,31,32,33,34], the exact mechanism for oxidation of organic materials on these electrodes in alkaline medium is still in dispute. Three types of active species for the oxidation of organics have been proposed, including Cu(III) species [30], radicals (e.g., hydroxyl radicals [30] or CuOOH ⋅ [7]), and surface-bonded copper (I) hydrous oxide species [Cu + ⋅ nH 2 O] ads [32].…”

“…The most accepted mechanism was proposed by Marioli and Kuwana [30], where Cu(III) species, e.g., CuOOH or Cu 2 O 3 , were treated as active species for oxidizing organics. The oxidization of organic compounds by Cu(III) species involves a redox mediation electron transfer process with hybrid-steps [34], which can be described as below [31]:Cu+ 2OH − → Cu(OH) 2 + 2e − Cu(OH) 2 + OH − → Cu(III)OOH +H 2 O + e − CuO+ OH − → Cu(III)OOH + e − CuO + H 2 O + 2OH − → Cu(OH) 4 − + e − Cu(III)OOH + Organics(red) + H 2 O → Cu(OH) 2 + Organics(ox) + OH − …”