Cyclic Voltammetry Methods Research Articles

Enhanced ePAD-DNA biosensor incorporating ZnO-NRs: Rapid and reliable electrochemical detection of field-isolated Pasteurella multocida

An electrochemical sensor has received much attention due to its importance for early infection identification, hinting at its critical relevance in diagnostic applications. For the detection of field-isolated strains of Pasteurella multocida, this paper reports the development and fabrication of a DNA-based electrochemical biosensor by integrating zinc oxide (ZnO) nanorods (NRs) into an electrochemical paper-based analytical device (ePAD). One significant improvement over the state-of-the-art features of the sensor is the using paper, an economically viable substrate that can be manufactured in large numbers. These sensors, being categorized under precision instruments with an ecologically friendly design, are ideal for mass production of eco-sensitive substrates. The biosensor is more sensitive and specific as compared to the conventional PCR-based sensing techniques. Moreover, the biosensor exploits the inherent properties of ZnO-NRs to amplify the signal output, whereas ePAD limits detection cost. In addition, a probe targeting the KMT gene of P. multocida was first characterized using conventional PCR and then immobilized onto the ZnO nanorods-modified ePAD surface, which improved the biosensor's ability for the rapid and selective genetic material of the pathogen detection. In addition, the sensor was validated using the methods of Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV). The reported biosensor it provides Linear Response of 0.001-10 μg/ml with LOD 0.001 μg/ml within a response time of 30 s. Subsequently, the biosensor reveals fast kinetics of the reaction as a powerful tool for timely and accurate diagnostics, pointing to its contribution to further development in biosensing technologies in the diagnostic area of infectious diseases at hospitals and clinics.

Conjugation of Doxorubicin and Carbon-based-nanostructures for Drug Delivery against HT-29 Colon Cancer Cells.

A drug delivery system is the method or process of administering a pharmaceutical compound to achieve a therapeutic effect in humans or animals. Such systems release the drugs at specific amounts in a specific site. The carbon based-nanomaterials have been actively used as drug carriers to treat various cancer. This study aimed to evaluate the cytotoxic effects of DOX-GO, DOX-OMC and DOXCNT in colon cancer cells (HT29). We reported platforms based on graphene oxide (GO), ordered mesoporous carbon (OMC) and carbon nanotubes (CNT) to conjugate with doxorubicin (DOX). The conjugation of DOX with carbon nanomaterial was investigated by UV-Vis spectroscopy, field emission scanning electron microscope (FE-SEM) and cyclic voltammetry (CV) methods. We showed that graphene oxide was a highly efficient matrix. Efficient loading of DOX, 89%, 78%, and 73.5% at pH 7.0 was seen onto GO, OMC and CNT, respectively. Upon pH 4. 0 after 15 h, 69%, 61% and 61% of DOX could be released from the DOX-GO, DOX-OMC and DOX-CNT, respectively, which illustrated the significant benefits of the developed approach for carbon nanomaterial applications. In vitro cytotoxicity analysis showed greater cytotoxicity of DOX/GO, DOX/OMC and DOX/CNT in comparison with GO, OMC and CNT against HT29 colon cancer cells with cell viability of 22%, 40% and 44% after 48 h for DOX-GO, DOX-OMC and DOX-CNT, respectively. The nanohybrids based on DOX-carbon nanomaterial, because of their unique physical and chemical properties, will remarkably enhance the anti-cancer activity.

Investigate of Electrochemical Properties of Nd(II) and Nd(III) in Eutectic LiCl-KCl Molten Salt

Pyroprocessing is one of the promising methods to reprocess the spent nuclear fuel. Neodymium (Nd) constitutes about one third of rare earth in fission products, however, the electrochemical properties of Nd have not been thoroughly understood, especially the exchange current. In the present study, the transit electrochemical methods of cyclic voltammetry and square wave voltammetry were applied to study the properties of Nd in LiCl-KCl system. The reduction of Nd3+ was determined as a two-step reaction with Nd3+/Nd2+ to be a reversible but Nd2+/Nd to be a quasi or irreversible reactions. Additionally, parameters such as the diffusion coefficient, exchange current, and apparent potential were derived from the cyclic voltammetry curves. Their relationship with temperature and concentration was investigated under 723 K, 773 K, 823 K with concentrations of 3 wt%, 6 wt% and 9 wt%. The present study contributes significantly to rich the database of Nd in LiCl-KCl molten salt and to understand the electrochemical behaviors of Nd during electrochemical separation of spent nuclear fuel.

Copper-Based Electrochemical Sensor Derived from Thiosemicarbazide for Selective Detection of Neurotransmitter Dopamine.

This paper presents the synthesis of the ligand 1-picolinoyl-4-cyclohexyl-3-thiosemicarbazide (H2pctc) and new metal complexes [Ni(Hpctc)2] (1), [Cu(Hpctc)Cl] (2), and [Cd(Hpctc)2] (3). The synthesized metal complexes were precisely characterized using single crystal X-ray diffraction (SC-XRD). In addition, complexes 1-3 were also characterized by UV-vis, fluorescence, and infrared spectroscopy. SC-XRD data confirmed the distorted octahedral geometry around the Ni(II) and Cd(II) centers and the distorted square planar geometry around the Cu(II) center. Data derived from the emission spectra depict that higher fluorescence intensity was exhibited by complexes 1, 2, and 3 in comparison to that of the free ligand H2pctc, and complex 3 showed the maximum intensity. Further, these metal complex-modified GCEs (glassy carbon electrodes) were utilized for electrochemical sensing of dopamine (DPM). The electrochemical studies of these complexes were performed using modified glassy carbon electrodes supported by electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods. In contrast to complexes 1 and 3, complex 2 is a superior electrode material with a high effective surface area for the electrochemical oxidation of DPM, according to the electrochemical response results. The derived sensor had a wide linear detection range of 1 to 1400 μM, an acceptable sensitivity of 0.01531 μA cm-2 μM-1, and a low LOD of 0.38 μM. The proposed approach was free of the interfering effects of ascorbic acid, uric acid, aminophenol, and other substances. During the successive scans, no fouling of the electrode surface was observed. The proposed electrochemical sensor had excellent stability, sensitivity, and a low detection limit making it suitable for the analysis of a variety of real samples. Additionally, it was proven to be useful for analyzing biological fluids.

Exploring the potential of SnSe/PANi composite counter electrodes for improved efficiency in dye-sensitized solar cells

This paper investigates the synthesis and characterization of novel counter electrodes (CEs) for dye-sensitized solar cells (DSSCs), focusing on composite polyaniline (PANi) nanofibers integrated with tin selenide (SnSe). Three CEs, namely SnSe, PANi, and their composite, were prepared via facile hydrothermal and cyclic voltammetry methods and compared with a standard platinum (Pt) CE. The efficiencies obtained were 4.20 %, 5.63 %, 8.39 %, and 7.72 % for SnSe, PANi, SnSe/PANi, and Pt CEs, respectively. The improved efficiencies, particularly in the case of the SnSe/PANi composite, were attributed to increased short-circuit density of the composite sample. The materials and devices prepared in this study are characterized using various methods including FESEM, TEM, XRD, Raman and FTIR spectroscopies, EIS, Tafel, OCVD, IPCE and etc to support our proposed CE structure. Our findings demonstrate the promising potential of SnSe/PANi composite CEs in enhancing the performance and affordability of DSSCs.

A Low-cost and Green Zinc-Iron Battery Achieved by Ethaline Deep Eutectic Solvent.

Deep eutectic solvents (DESs) were considered as a potential electrolyte because of their low price, harmless to environment and wider electrochemical window potential compared to water. In this work, Fe(Ⅲ)/Fe(Ⅱ) and Zn(Ⅱ)/Zn redox couples were used as the positive and negative active materials, respectively, in a DES system using choline chloride and ethylene glycol in a molar ratio of 1:2 (ethaline). The possible working mechanism of the battery was studied by cyclic voltammetry, spectroscopic and simulation methods. The effects of different temperatures, concentrations of zinc ions in the anolyte and current densities on battery performance were evaluated. The results showed that the designed zinc-iron battery should preferably be operated at a current density of 0.5 mA cm-2 and the temperature of 313~323 K, which will improve the energy efficiency and maintain a high coulombic efficiency. The variation of cycle performance test presents a different pattern from the usual batteries, which is due to the effect of RO- group. At 313 K and 0.5 mA cm-2, the coulombic efficiency increases from 14.1% to 100.2% after 46 cycles, and then remains at about 100% during the rest 54 cycles, which demonstrates a good cycle stability of DES-based zinc-iron battery.

Manganese Electrochemistry in a Deep Eutectic Solvent: The Effects of KBr

AbstractThis work reports the effects of potassium bromide (KBr) on the electrodeposition of manganese on copper from a DES consisting of a stoichiometric 1:2 mix of choline chloride and ethylene glycol (Ethaline 200). The speciation of MnCl2.4H2O in Ethaline 200 has been investigated using UV–vis spectroscopy, in particular with regard to the addition of KBr to the plating bath, for which no apparent change in the Mn species was noted. This said, the physical properties of the manganese deposits themselves were found to have been considerably improved in comparison to when KBr was omitted from the bath; indeed, the actual adhesion of Mn was achieved for the first time on a copper substrate, somewhat remarkably producing a coating of some considerable thickness. Given its clear electrochemical behavior of the Mn liquid were subsequently determined via cyclic voltammetry method. A reduction in the peak current of Mn was noted on addition of KBr. The mechanism of Mn deposition has been examined via chronocoulometry and chronoamperometry. Surface analyses of Mn deposits have been conducted via SEM/EDX, AFM, and XRD, from which improvements to the Mn surface coatings in depositions performed from an electrolyte containing 0.1 M KBr were noted.

Effect of Carbon Nanotubes Functionalization on the Chemical Composition and Electrochemical Characteristics of Composites with Layered Potassium Manganese Oxide

The influence of pretreatment of multiwalled carbon nanotubes (MWCNTs) in oxidizers (solutions of H2O2 and HNO3) on the structure and electrochemical properties of composites with layered potassium-manganese oxide (KxMnO2) was studied. Composites were obtained by soaking carbon nanotubes in an aqueous solution of KMnO4 at 60 °C. The electrochemical performance of the composites was evaluated by cyclic voltammetry and galvanostatic charge‒discharge methods. It has been established that stronger oxidation of the MWCNTs surface at the functionalization stage leads to a noticeable increase in the reaction rate as well as the optimal potassium content in the KxMnO2 composition, which provides higher capacitive characteristics of the composite (a maximum specific capacitance of 150 F g−1 and a rate capability of 43% with increasing density current from 0.1 to 2.0 A g−1). The resulting composites are promising active components for increasing the capacitive characteristics of conductive carbon black (CB). Compared with an electrode based only on CB, electrodes based on a combination of the composite and CB at a mass ratio of 1:1 showed specific capacitance values approximately 1.5 to 3 times greater, as well as a twofold increase in rate capability (from 35 to 70%) in the range of discharge current density 0.1 to 2.0 A g−1.

Electrochemical Reactivity of Hydrogen Storage Materials: Exploring Borohydride and Hydrazinium Salt Mixtures

Electrochemical characterization of hydrogen storage materials was conducted in a non-aqueous environment to investigate the direct electrochemical release and consumption of hydrogen and the potential for regeneration. We first address the challenge of minimal solubility of the synthetic precursors, sodium borohydride (NaBH4) and hydrazinium bromide (N2H5Br), in both organic and inorganic solvents. We next determine and calibrate a reference electrode formulation compatible with our non-aqueous media and analytes that demonstrates a stable reference potential. We employ cyclic voltammetry (CV) to characterize the precursors and mixtures thereof. Each CV peak is assigned to a corresponding electrochemical reaction. Using the rate-dependent CV method and Randles–Ševčík equation, we calculate the diffusion coefficient of each chemical (NaBH4 and N2H5Br). Analysis of the CVs, coupled with 11B NMR analysis, reveals a room temperature chemical transformation of NaBH4 and N2H5Br mixtures into hydrazine borane (N2H4BH3). These results are particularly significant, considering the limited information available on the electrochemical characterization of metal borohydride and hydrazinium salt in non-aqueous media. This work establishes a foundation for adapting a non-aqueous electrochemical system to further study the borohydride family of chemistries and to design and develop electrochemical devices for direct electrical and chemical energy interconversion with hydrogen storage materials.

Electrodeposited ZnO Nanostructures on ITO Surfaces: Exploring Their Efficacy for Cholesterol Biosensing Applications

In this study, ZnO nanostructures were prepared by electrochemical anodization of electrodeposited Zn on ITO/glass substrates for cholesterol detection. The efficiency of the developed ZnO nanostructures in the detection of the Cholesterol oxidase (ChOx) enzyme was determined by the cyclic voltammetry method. The XRD and SEM results confirmed the synthesis of ZnO nanostructures prepared by the anodization method with various parameters. The effect of electrodeposition and anodization time on the morphology was observed. Cyclic voltammetry of ZnO/Zn/ITO/glass and Pt/ZnO/Zn/ITO/glass electrodes in electrolytes with various cholesterol concentrations was performed. The detection limit of the obtained Pt/ZnO/Zn/ITO/glass structured electrode was calculated as 0.965x10-3M. The resulting material with a layered structure may have potential applications in electrochemical sensors and biosensors in biomedical applications. In addition to biosensing performance, this study proposes a new approach for the development of ZnO-based biosensors that does not require expensive infrastructure and raw material costs, making it possible to develop high-sensitivity biosensor electrodes with lower detection limits with improvements to be made in future studies.

Electrochemical Production of Tungsten Oxides from Wc-Co Carbide-Type Pseudo-Alloy Waste

Electrochemical research is devoted to the development of a method of processing secondary raw materials containing tungsten in the form of a pseudoalloy of the carbide type WC–Co in sulfate solutions. The target processing products are: powders of tungsten oxides of lower oxidation states, which can be reduced to metallic tungsten with lower costs. Using the methods of linear and cyclic voltammetry, it was established that the selective dissolution of the cobalt component of the pseudoalloy in the studied solutions occurs at potentials more positive than 0.2 V, carbon is removed from the working electrode at a potential > 0.8 V. At the same time, tungsten is oxidized to the higher oxide WO3. It was determined that in sulfuric acid, with an increase in its concentration from 1 to 5 mol∙dm-3, the current density decreases, which is associated with the formation of a solid surface layer of tungsten oxide on the surface of the anode, which passivates the surface. It was established experimentally that when adding 1 mol∙dm-3 of H2SO4 hexamine (C6H12N4) with a concentration of 0.9 mol∙dm-3 to a solution, it is possible to block the process of formation of a passivating film and obtain powders of tungsten oxides of lower oxidation states.

Enhancing of hydroquinone and catechol oxidation using a graphite and graphene composite polymer modified paste electrode

ABSTRACT An innovative electrochemical redox response of hydroquinone (HQN) and catechol (CCL) was analysed using a bare graphite and graphene composite paste electrode (BGGCPE) and polymerised L-leucine modified graphite and graphene composite paste electrode (LCN-MGGCPE) was successfully developed in 0.2 M phosphate buffer solution (PBS) with pH 6.0 at a 0.1 V/s scan rate. Fabricated electrode using simple and cost-effective method, the polymerised LCN-MGGCPE surface shows more electrochemical activity, sensitivity and selectivity towards the determination for HQN and CCL. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), Differential pulse voltammetry (DPV), and electrochemical impudence spectroscopy (EIS) were utilised as analytical techniques while LCN-MGGCPE and BGGCPE surface characterisation were studied using a scanning electron microscopy (SEM) technique. LCN-MGGCPE exhibited superior electrochemical activity compared to BGGCPE towards the oxidation responses of both HQN and CCL. Additionally, the effect of pH studies, scan rate change for HQN, and concentration change of analyte molecule were examined, with the 0.025 to 0.500 V/s scan rate varied and revealing an adsorption-controlled process. The concentration changes of CVs methods ranged from 0.2 to 320 μM, DPVs ranged from 0.2 to 1100 μM and LSVs ranged from 0.2 to 850 μM, the calculated a limit of detection (LOD) of CV, DPV, and LSV, is 0.020 μM, 0.026 μM, and 0.011 μM and a limit of quantification (LOQ) of 0.068 μM, 0.088 μM, and 0.035 μM. The electrochemically developed LCN-MGGCPE shows good reproducibility, repeatability, stability, sensitivity and simultaneous analysis of analyte molecules were studied. This study presents a promising pathway for the growth of effective sensors for the determination of HQN in medicinal and water sample applications.

A Dinitrogen Divanadium Complex Supported by a Trisamidophosphine Ligand

Comprehensive SummaryThe reaction between tripodal trisamidophosphine ligand H3PN3Ar and V(Mes)3(THF) (Mes = mesityl) yields the vanadium(III) complex (PN3Ar)V (1) with an open site in the axial position, which could coordinate with THF, pyridine, and NH3 to form the corresponding adducts (2—4). The vanadium(III) center is redox‐active, as demonstrated by cyclic voltammetry methods and chemical oxidation or reduction. Notably, a novel dinitrogen divanadium complex with a bridging N2 ligand, {K(THF)}2{[PN3Ar]V}2(μ‐N2) (6), was synthesized via treatment of 1 with 1 equivalent of potassium naphthalenide in THF under a N2 atmosphere. The electronic structures and binding properties of 6 are evaluated and discussed based on its DFT calculations. Additionally, these vanadium complexes (1, 5, 6) can serve as catalysts for the conversion of N2 into N(SiMe3)3 in the presence of reductants and Me3SiCl.

Fe-doped WO3-Modified sensor for the improved electrochemical detection of curcumin

In this study, an iron-doped tungsten oxide (Fe-WO3) nanomaterialwas synthesizedand utilized to modify carbon paste electrodes for the identification of the bioactive ingredient curcumin (CUM). Turmeric contains a bioactive compound called curcumin, which is yellow and has various potential biological applications, such as being an anti-carcinogenic, anti-inflammatory, and antioxidant agent. The Fe-WO3 nanomaterial underwent characterization through SEM, XRD, and EDS techniques. The electrochemical performance of CUM was inquired using square wave and cyclic voltammetry methods. During catalytic oxidation, the Fe-WO3 working electrode assembly showed faster electron transport than the bare CPE. Investigations havebeen conductedinto the kinetics of oxidation, and the developed sensor demonstrated an excellent linear detection range (5 μM to 60 μM), a decreased limit of detection (6.2 × 10−8 M), and a limit of quantification under optimal conditions (20.7 × 10−8 M).The numbers of electrons transmitted, the heterogeneous rate constant, the electron transfer coefficient, and the electrochemical oxidation were all measured. The results from the examination of CUM in actual samples using the devised Fe-doped WO3 modified electrode were good. Additionally, it showed a considerable increase in the curcumin peak current concerning responsively, specificity, and reliability for curcumin analysis.

Current Mirror Improved Potentiostat (CMIPot) for a Three Electrode Electrochemical Cell.

This work presents a novel compact CMOS potentiostat-designed circuit for an electrochemical cell. The proposed topology functions as a circuit interface, controlling the polarization of voltage signals at the sensor electrodes and facilitating current measurement during the oxidation-reduction process of an analyzed solution. The potentiostat, designed for CMOS technology, comprises a two-stage amplifier, two current mirror blocks coupled to this amplifier, and a CMOS push-pull output stage. The electrochemical method of cyclic voltammetry is employed, operating within a voltage range of ±0.8 V and scan rates of 10 mV/s, 25 mV/s, 100 mV/s, and 250 mV/s. The circuit is capable of reading currents ranging from 10 µA to 500 µA. Experimental results were obtained using a potassium ferrocyanide K3[Fe(CN)6] redox solution with concentrations of 10, 15, and 20 mmol/L, and their corresponding voltammograms were evaluated. The experimental results from a discrete circuit demonstrate that the proposed potentiostat topology produces outcomes consistent with those of classical topologies presented in the literature and industrial equipment.

Oxygen‐Doped Graphitic Carbon Nitride for Electrochemical Uric Acid Sensing: Method Without Metals

AbstractThe present study examined potential benefits of heteroatom doping to manipulate the electrical structure and to enhance the efficiency of the sensor, with an emphasis on developing inexpensive, metal‐free electrochemical sensors. Melamine and ammonium oxalate were used as precursors in a one‐step thermal polymerization technique yielding oxygen‐doped graphitic carbon nitride (O‐gCN). Following synthesis, the material's structural and morphological properties were thoroughly examined using a multitude of analytical techniques, including EIS. A notable decrease in impedance was observed, suggesting improved conductivity. Additionally, the doping approach exhibited a noticeable improvement in reduction current receptivity and surface area as compared to unmodified graphitic carbon nitride (g‐CN). Utilizing both differential pulse voltammetry (DPV) and the classical cyclic voltammetry (CV) methods, we investigated the electro oxidation of uric acid (UA) as well as concentration dependence and selectivity studies using oxygen‐doped graphitic carbon nitride modified glassy carbon electrode (O‐gCN@GCE). O‐gCN@GCE demonstrated remarkable performance, allowing the detection of UA concentrations as low as 7.784 µAµM−1cm−2. Its low detection limit of 0.57 µM and wider linear range (5–120 µM) further highlighted its potential for extremely sensitive assays and its remarkable capacity to operate over a broad UA concentration range.

Effect of microstructure on hydrogen uptake in SA 210 grade A1 steel studied using cyclic voltammetry and hydrogen permeation method

Effect of microstructure on hydrogen uptake in SA 210 grade A1 steel studied using cyclic voltammetry and hydrogen permeation method

Highly sensitive MXene-based voltammetric sensor for nanomolar clozapine detection

Clozapine is vital for managing schizophrenia and other psychiatric disorders. As a potent medication with risks of severe side effects, accurate detection ensures effective treatment monitoring, patient safety, and optimization of therapeutic outcomes. Herein, niobium carbide two-dimensional transition metal carbides (Nb2CTx MXene) was prepared by etching niobium aluminum carbide (Nb2AlC), which was next partially oxidized by a hydrothermal method to niobium oxide (Nb2O5)/Nb2CTx and ultrasonically bound to carboxylated multi-walled carbon nanotubes (MWCNTs-COOH). It was modified onto a glassy carbon electrode for the detection of the antipsychotic drug clozapine ingested by humans. The morphology and electrochemical properties of MXene-based nanocomposite electrode were verified by scanning electron microscopy, X-ray diffractometry, Raman, cyclic voltammetry and electrochemical impedance characterization methods. The results showed that electrode responded well to clozapine solutions, with good linearity (R2 = 0.9979 and 0.9995) of the peak currents with clozapine concentrations (0.01–1.0 μM and 1.0–10.0 μM) and that this sensor had good immunity, repeatability, reproducibility and stability. The limit of detection was 8.38 nM and the recovery was 92.5 % ~ 106.5 % in real serum and urine samples. The MXene-based sensors offer excellent analytical performance and hold promise for cost-effective generalisation to the detection of nanomolar clozapine in a variety of clinical applications.

A photoelectrochemical sensor based on polydopamine membrane-coated CdS@C core-shell heterostructure for curcumin detection

Curcumin has been widely employed in various fields, but excessive intake may cause tissue necrosis and pose a serious threat to people’s lives and health. Hence, it is crucial to rapidly and precisely detect the content of curcumin. In present research, CdS@C heterostructure materials were successfully prepared through a one-pot solvothermal reaction strategy, utilizing glucose as the carbon source. Simultaneously, polydopamine thin films (ePDA) were successfully deposited on the surface of CdS@C-modified electrodes by the cyclic voltammetry (CV) method. A photoelectrochemical sensor based on the polydopamine membrane-coated CdS@C core–shell heterostructure (ePDA/CdS@C) was designed for curcumin detection. Furthermore, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible spectrophotometers (UV-vi) techniques were applied to characterize the structure and morphology of the synthesized photoelectric materials. The ePDA coating enhances the stability of the CdS@C material, and the CdS@C core-shell heterostructure accelerates electron transfer. Consequently, the ePDA/CdS@C material generates an outstanding and steady photocurrent response. Under ideal conditions, the novel sensor exhibits a satisfactory linear response to curcumin detection within the concentration range of 0.025–370 μM, with a detection limit as low as 0.0165 μM. Additionally, the ePDA/CdS@C-based photoelectrochemical aptasensor displays remarkable reproducibility, stability, and selectivity. This innovative sensing platform accurately detects curcumin in human serum and urine samples, with an excellent recovery range (99.47 %–103.60 %) and relatively low RSD values (1.49 %–3.56 %). In conclusion, this work offers a novel approach for curcumin detection.

Validation and application of the square wave voltammetry method for the electrochemical determination of eszopiclone in pharmaceutical formulations and human biological fluids using glassy carbon electrode

A buffer solution of Britton-Robinson (B-R) pH 6.5 was utilized to validate and apply a square wave voltammetry (SWV) method for the electrochemical determination of Eszopiclone (ESP) in pharmaceuticals and biological samples. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods were employed in the initial study of the voltammetric behavior of the ESP compound. The rotating glassy carbon (GC) indicator electrode (2.0 mm2), Pt auxiliary electrode, and Ag/AgCl reference electrode were used for ESP determination. ESP was analyzed to produce a sharp reduction peak at a potential of −750 mV. The best shape and high sensitivity of SWV cathodic current for ESP, were observed using GC electrode, B-R, pH 6.5, accumulation time (tacc) of 60-second, accumulation potential (Eacc) of - 0.1 V, amplitude voltage of 150 mV, frequency of 15 Hz, scan rate of 150 mV s−1, and stirrer rate of 1000 round per minute (rpm). The electroanalytical performance of the SWV method was evaluated through study of repeatability, stability, calibration curve, recovery, and limits of detection and quantification (LOD,LOQ). Under the optimal conditions, the SWV response was linear in the range from 3 × 10−6 to 5 × 10−5 mol/L (n = 10). The SWV method achieved a LOD of 1.9 × 10-8 mol/L (7.5 ppb), and a LOQ of 6.41 × 10−8 mol L−1 (24.93 ppb). The validated SWV method was appeared the good repeatability, sensitivity and stability for the determination of ESP. It was given a very stable SWV current for 90 min, with a 0.141 % relative standard deviation (RSD%). The SWV method was applied to the determination of ESP in pharmaceutical tablets and biological samples.