Sensitive Square-wave Voltammetry Research Articles

First Electrochemical Approach to Voltammetric Behavior and Sensing of Anticancer Drug Ponatinib

This study investigated for the first time the electrochemical behavior of the anticancer drug ponatinib (Pon). All voltammetric experiments were conducted using square-wave voltammetry (SWV) and cyclic voltammetry (CV), with a boron-doped diamond electrode (BDDE) as a working electrode. The recorded voltammograms showed a well-defined oxidation peak for Pon at a positive potential value of around +1.35 V (vs Ag/AgCl) in hydrochloric acid of pH 1.3. The study also analyzed the influence of experimental conditions, such as pH and composition of supporting electrolyte, as well as the parameters of the square-wave voltammetric technique. A rapid, simple, and sensitive SWV methodology was established for the determination of ponatinib in the concentration range of 1.0 × 10−6–2.0 × 10−5 mol l−1, with a detection limit of 2.5 × 10−7 mol l−1. The biological significance of the developed SWV procedure was demonstrated by a quantitative analysis of ponatinib in spiked urine samples with a highly satisfactory rate of recovery. In addition, the effect of some interfering agents coexisting in the human urine on the peak current of Pon was evaluated. Cyclic voltammetry was used to study the electrochemical behavior of the analyte. The obtained results indicated that the oxidation of ponatinib was an irreversible process and was controlled by diffusion. The number of electrons and protons involved in the oxidation process was also estimated.

A Comparison of Edge‐plane and Basal‐plane Pyrolytic Graphite Electrodes towards Sensitive Determination of the Fungicide Mandipropamid

AbstractA sensitive square‐wave voltammetry (SWV) method based on basal‐plane pyrolytic graphite electrode (BPPGE) and edge‐plane pyrolytic graphite electrode (EPPGE) was developed to determine the concentration of the pesticide mandipropamid (MAN) in spiked river water and grape juice samples. Under optimal experimental conditions, the SWV response of EPPGE and BPPGE was linear over the concentration ranges of 0.7 to 9.0 μmol L−1 and 0.5 to 10.0 μmol L−1, respectively. The method was successfully used to determine MAN in spiked samples with good recovery. Cyclic voltammetry (CV) was conducted to understand the mechanism underlying the electrode process of MAN.

Nanostructured Ba/ZnO modified electrode as a sensor material for detection of organosulfur thiosalicylic acid

Electrochemical sensors are regulated by the interaction of several chemical solutions to generate an electrical signal proportional to the concentration of the analytes. A novel electrochemical sensor is reported in this study for an organosulfur molecule, thiosalicylic acid (TSA) detection by the casting of electro-catalytic barium doped zinc oxide nanoparticle suspension on a glassy carbon electrode (GCE). The electrochemical response of TSA was examined simultaneously for bare GCE and electro-chemically modified GCE, i.e. Barium doped zinc oxide nanoparticle/GCE (BDZONPs/GCE) by utilizing different voltammetric techniques in an acidic medium of pH 3.0. In comparison with the bare GCE, the modified GCE exhibits a decent response towards oxidation of TSA with a well-defined peak current. The catalytic nature, conducting nature, and large surface area of the nanoparticles which influences the remarkable enhancement of the TSA at BDZONPs/GCE was examined. The impact of accumulation time, pH dependency, and the scan rate variation were also studied. Based on the experimental data the physicochemical parameters were being calculated. The sensitive squarewave voltammetry (SWV) was used to monitor the low detection limit of TSA. Applicability of proposed work showed good sensitivity, selectivity, and noticeable recovery results with BDZONPs/GCE.

Electrochemical and spectroscopic studies of the interaction of antiviral drug Tenofovir with single and double stranded DNA

In the present study, the electrochemical behavior of the antiviral drug tenofovir (tnf) on a boron-doped diamond electrode (BDDE) has been studied using square-wave voltammetry (SWV). The experimental conditions such as the supporting electrolyte composition and the SWV parameters were optimized. Under the optimized conditions, a simple and sensitive SWV procedure for tnf determination was developed in the concentration range of 5.0 × 10−6 to 1.0 × 10−4 mol L−1. The calculated limit of detection and limit of quantification were equal to 5.6 × 10−7 and 1.9 × 10−6 mol L−1, respectively. The biological significance of the developed method was demonstrated by a quantitative analysis of the pharmaceutical formulations Viread and Tenofovir disoproxil Teva. Moreover, both voltammetric and spectroscopic techniques were used to study the interaction between tnf and DNA. Changes in the electrochemical and spectroscopic behavior of tnf in the presence of DNA were used to calculate the binding constants of the formed complexes. The estimated values of Gibbs free energy revealed that the formation of the drug–DNA complexes was a spontaneous and favorable process. Moreover, for free and bound tenofovir, kinetic parameters such as heterogeneous rate constant, electron transfer coefficient, and diffusion coefficient were determined.

Electrochemical sensor for leukemia drug imatinib determination in urine by adsorptive striping square wave voltammetry using modified screen-printed electrodes

A sensitive square wave voltammetry (SWV) method at screen-printed carbon electrodes was developed to determine imatinib in human urine using prepared multi-walled carbon nanotubes modified with carboxyl groups (MWCNT-COOH) as working electrode. The electrochemical behavior of the imatinib was investigated under several electrodes types and by three different voltammetric techniques: cyclic (CV), differential pulse (DPV) and square wave voltammetry (SWV). Quantitative analysis was carried out through its oxidation process at + 0.7 V, pH 7 and accumulation time of 120 s. The SWV method was linear in the range 50 nM–912 nM. The derivative signal of SW voltammogram resulted in limits of detection (LOD) and limit of quantification (LOQ) twice lower as SWV method (LOD 7 nM and LOQ 23 nM). The method was successfully applied for the determination of imatinib in real clinical urine samples from patients with chronic myeloid leukemia and the results were corroborated by capillary electrophoresis. Imatinib contained in patients urine samples was determined following the standard addition method using the same screen-printed electrode. In the present method, the only urine treatment was a simple dilution with the supporting buffer.

A Study on the Copper Effect on gold leaching in copper-ethanediamine-thiosulphate solutions

A simple, fast and sensitive square-wave voltammetry (SWV), cyclic voltammetry(CV) and tafel method for the determination of various factors of gold in thiosulphate solution in this paper. We present our study on the effect of copper(II) on the leaching of gold in thiosulphate solutions. The current study aims to establish the interaction of copper in the leaching process by electrochemical method.

First Electroanalytical Studies of Profluralin with Square Wave Voltammetry Using Glassy Carbon Electrode

AbstractThe electrochemical behaviour of profluralin (PFL) was investigated with square wave voltammetry (SWV) and cyclic voltammetry at bare and modified with graphene, graphene oxide, reduced graphene oxide, carbon nanotubes glassy carbon electrode. The influence of various factors such as pH, buffer composition, ionic surfactants and voltammetric parameters was studied. The best results in terms of signal shape and intensity were recorded in 0.04 M Britton‐Robinson buffer at pH 2.0 at −0.43 V versus Ag/AgCl. In acidic medium profluralin produces single cathodic signal of an irreversible nature. Observed peak (two superimposed signals from two nitro groups) is a result of PFL reduction controlled by diffusion processes. Linearity of peak currents (Ip) vs. concentrations of profluralin was found in the range of 1.0×10−7 to 1.0×10−6 M with a detection limit of 2.6×10−8 M using fast and sensitive SWV. The developed method has been applied for the quantitative analysis of profluralin in spiked environmental samples with very good average recoveries in the range from 98.6 to 99.9 % with a mean relative standard deviation of 4.0 %.

Electrochemical behavior of kaempferol and its determination in presence of quercetin employing multi-walled carbon nanotube modified carbon paste electrode

The electrochemical behavior of kaempferol was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) at plane and multiwalled carbon nanotubes modified carbon paste electrode (MWCNTs/CPE). Kaempferol produces an anodic peak at MWCNTs modified CPE with a quasi-reversible nature in phosphate buffer of pH 7.73. The oxidized species of kaempferol was found to be stable (Ipa/Ipc ≈1) over scan rates of 100∼600 mV−1. The same electrode was also found to catalyze the electrode oxidation of quercetin in presence of kaempferol under similar conditions which enabled the simultaneous determination of kaempferol and quercetin. Linearity of peak currents (Ip) vs. concentrations of kaempferol and quercetin was found in the range of 6.72 × 10−9 M to 40.34 × 10−9 M with a detection limit of 2.90 × 10−9 M for kaempferol and 13.0 × 10−9 M to 50.9 × 10−9 M with a detection limit of 3.5 × 10−9 M for quercetin using fast and sensitive SWV. The developed method has been applied for the quantitative analysis of kaempferol in corms and petals of Indian traditional medicine saffron (Crocus sativus) using a phosphate buffer of pH 7.73 and the average percent recoveries obtained are 99.84 and 99.26, respectively.

Electrochemical behavior of kaempferol and its determination in presence of quercetin employing multi-walled carbon nanotube modified carbon paste electrode

The electrochemical behavior of kaempferol was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) at plane and multiwalled carbon nanotubes modified carbon paste electrode (MWCNTs/CPE). Kaempferol produces an anodic peak at MWCNTs modified CPE with a quasi-reversible nature in phosphate buffer of pH 7.73. The oxidized species of kaempferol was found to be stable (Ipa/Ipc ≈ 1) over scan rates of 100–600 mV−1. The same electrode was also found to catalyze the electrode oxidation of quercetin in presence of kaempferol under similar conditions which enabled the simultaneous determination of kaempferol and quercetin. Linearity of peak currents (Ip) vs. concentrations of kaempferol and quercetin was found in the range of 6.72 × 10−9 M to 40.34 × 10−9 M with a detection limit of 2.90 × 10−9 M for kaempferol and 13.0 × 10−9 M to 50.9 × 10−9 M with a detection limit of 3.5 × 10−9 M for quercetin using fast and sensitive SWV. The developed method has been applied for the quantitative analysis of kaempferol in corms and petals of Indian traditional medicine saffron (Crocus sativus) using a phosphate buffer of pH 7.73 and the average percent recoveries obtained are 99.84 and 99.26, respectively.

Electrochemical studies of quinine in surfactant media using hanging mercury drop electrode: A cyclic voltammetric study

The electrochemical behavior of quinine was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) using surfactant. The reduction peak current of quinine increases remarkably in presence of 1% CTAB. Its electrochemical behavior is quasi-reversible in the Britton–Robinson buffers of pH 10.38 by exhibiting the well-defined single cathodic and anodic waves and the ratio of Ipa/Ipc approaching one at the scan rate of 500mVs−1. On the basis of CV, SWV and Coulometry, electrochemical reduction mechanism of quinine has been proposed which has shown that protonation occurs on the nitrogen of the quinoline moiety. Linearity was obtained when the peak currents (Ip) were plotted against concentrations of quinine in the range of 30.0–230.0ngmL−1 with a detection limit of 0.132ngmL−1 in SWV and 90.0–630.0ngmL−1 with a detection limit of 0.238ngmL−1 in DPV. Fast and sensitive SWV has been applied for the quantitative analysis of quinine in bark of Cinchona sp. and in soft drinks and a good recovery was obtained. The accuracy and precision of the method are determined and validated statistically. No interferences from other food additives were observed. The relative standard deviation for intraday and interday assay was 0.89 and 0.73% (n=3) respectively.

An integrated electrochemical device based on immunochromatographic test strip and enzyme labels for sensitive detection of disease-related biomarkers

A novel electrochemical biosensing device that integrates an immunochromatographic test strip and a screen-printed electrode (SPE) connected to a portable electrochemical analyzer was presented for rapid, sensitive, and quantitative detection of disease-related biomarker in human blood samples. The principle of the sensor is based on sandwich immunoreactions between a biomarker and a pair of its antibodies on the test strip, followed by highly sensitive square-wave voltammetry (SWV) detection. Horseradish peroxidase (HRP) was used as a signal reporter for electrochemical readout. Hepatitis B surface antigen (HBsAg) was employed as a model protein biomarker to demonstrate the analytical performance of the sensor in this study. Some critical parameters governing the performance of the sensor were investigated in detail. Under optimal conditions, this sensor was capable of detecting a minimum of 0.3ngmL−1 (S/N=3) HBsAg with a wide linear concentration range from 1 to 500ngmL−1. The sensor was further utilized to detect HBsAg spiked in human plasma with an average recovery of 91.3%. In comparison, a colorimetric immunochromatographic test strip assay (ITSA) was also conducted. The result shows that the SWV detection in the electrochemical sensor is much more sensitive for the quantitative determination of HBsAg than the colorimetric detection, indicating that such a sensor is a promising platform for rapid and sensitive point-of-care testing/screening of disease-related biomarkers in a large population.

Electrochemical study of the thermodynamics and kinetics of hydrophilic ion transfers across water | n-octanol interface

Thermodynamics and kinetics of hydrophilic ion transfers across water|n-octanol (W|OCT) interface have been electrochemically studied by means of novel three-phase and thin-film electrodes. Three-phase electrodes used for thermodynamics measurements comprise edge plane pyrolytic graphite, the surface of which was partly modified with an ultrathin film of OCT, containing hydrophobic lutetium bis(tetra-tert-butylphthalocyaninato) (Lu[tBu4Pc]2) as a redox probe. The transfers of anions and cations from W to OCT were electrochemically driven by reversible redox transformations of Lu[tBu4Pc]2 to chemically stable lipophilic monovalent cation \({\left( {{\text{Lu}}{\left[ {t{\text{Bu}}_{4} {\text{Pc}}} \right]}^{ + }_{2} } \right)}\) and anion \( {\left( {{\text{Lu}}{\left[ {t{\text{Bu}}_{{\text{4}}} {\text{Pc}}} \right]}^{{\,\, - }}_{2} } \right)} \), respectively. Upon reduction of Lu[tBu4Pc]2, the transfers of alkali metal cations from W to OCT have been studied for the first time, enabling estimation of their Gibbs transfer energies. For kinetic measurements, a thin-film electrode configuration has been used, consisting of the same electrode covered completely with a thin layer of OCT that contained the redox probe and a suitable electrolyte. Combining the fast and sensitive square-wave voltammetry with thin-film electrodes, the kinetics of \( {\text{ClO}}^{{\,\, - }}_{4} \), \( {\text{NO}}^{{\,\,{\text{ - }}}}_{{\text{3}}} \), and Cl− transfers have been estimated.

Electrochemical behavior and square wave voltammetric determination of doxorubicin hydrochloride

The electrochemical behavior of doxorubicin hydrochloride was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). From CV and SWV studies of doxorubicin hydrochloride in the acetate buffers of various pH values, it was found that protons were involved in the reduction of the antibiotic at the H+/e- ratio at one (deltaEp/pH = -53 approximately -61 mV at 23 degrees C), proposing the electrochemical reduction of the quinone moiety in its anthraquinone aglycone. Its electrochemical behavior was pseudo-reversible in the acetate buffer of pH 3.5 by exhibiting the well-defined single cathodic and anodic waves and the ratio of Ip(a)/Ip(c) at approximately one over the scan rates of 10 approximately 100 mV/s. Fast and sensitive SWV showing a single peak of doxorubicin has been applied for its quantitative analysis using an acetate buffer of pH 3.5. A linearity was obtained when the peak currents (Ip) were plotted against concentrations of doxorubicin in the range of 5.0 x 10(-7) M approximately 1.0 x 10(-5) M with a detection limit of 1.0 x 10(-7) M.

Remote electrochemical sensor for monitoring TNT in natural waters

An electrochemical sensor for remote continuous monitoring of the explosive 2,4,6-trinitrotoluene (TNT) is described. The probe relies on rapid and sensitive square-wave voltammetry at a submersible carbon-fiber working-electrode assembly, connected to a 50ft-long shielded cable. Operational conditions have been optimized to meet the specific requirements of remote operations. Tests with untreated river water, groundwater, and drinking water samples, spiked with TNT, displayed results similar to those obtained with synthetic buffer solutions. Due to the low detection potential of TNT, coexisting sample constituents do not contribute to the response. The use of ultrafast square-wave voltammetric scanning, without a regeneration step, leads to a rapid detection of dynamic concentration changes, low ppb detection limits, and high stability. Prospects for using the electrochemical probe for real-time monitoring of TNT are discussed.