Square-wave Voltammetric Method Research Articles

Voltammetric analysis of mephenoxalone drug in pharmaceutical and biological samples using novel screen-printed sensor with boron-doped diamond electrode

A novel screen-printed sensor (SPE) with boron-doped diamond electrode (BDDE) for determination of a muscle relaxant and mild anxiolytic mephenoxalone (MNL) was developed. The sensor utilizes the electrochemical oxidation of MNL, which was firstly studied in aqueous solution using oxygen terminated BDDE. MNL provided an irreversible anodic signal at a potential of + 1380 mV (vs. Ag/AgCl/KCl sat.) over a wide pH range. Britton-Robinson buffer (pH 9) was selected as a suitable electrolyte and the square-wave voltammetric method (SWV) was developed. The low detection limit (55 nmol L–1), wide linear dynamic range (0.1–30 µmol L−1), and good recovery in the analysis of model and pharmaceutical samples (RSD < 1.77%) were attained. Subsequently, the new method was successfully transferred to SPE, which can find application in point-of-care testing. These sensors proved excellent sensitivity and reproducibility in the analysis of biological samples (RSD < 4.94%) without pretreatment and no need of electrolyte. Based on gas chromatography with mass spectrometry (GC-MS) analysis of preparative electrolysis products, a mechanism of the electrochemical oxidation of MNL was proposed, describing the oxidative cleavage of the alkoxybenzene ring. These results were supported with HOMO spatial distribution calculations and atomic charges calculations for arising radical cations, and with spectroelectrochemical measurements.

Quantification of ferulic acid using square-wave voltammetric method at an unmodified boron-doped diamond electrode

Quantification of ferulic acid using square-wave voltammetric method at an unmodified boron-doped diamond electrode

Monitoring antiviral active metabolite (N-hydroxycytidine) levels in plasma in presence of carboxylesterase-2 inhibitor verapamil using copper tetracyanoquinodimethane enhanced sensor

This study focuses on the determination of the active metabolite of molnupiravir (MOL), N-hydroxycytidine (NHC), using a square wave voltammetric (SWV) method. Carboxylesterase-2 enzymes catalyze the conversion of MOL prodrug into NHC. However, co-administration of verapamil (VER), a carboxylesterase-2 inhibitor, may reduce the levels of NHC, leading to decreasing its antiviral activity. In this context, the levels of NHC and VER were simultaneously monitored using a carbon paste electrode modified with phase I of copper tetracyanoquinodimethane (CuTCNQ) which is highly conductive charge transfer complex. The as-designed sensor was characterized successfully using various spectroscopic techniques and Scanning Electron Microscopy (SEM). The electrochemical behavior of the newly fabricated probe was examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). This method demonstrated its efficacy in measuring NHC and VER levels in rabbit plasma samples, showing high sensitivity and selectivity. The calibration plots for the simultaneous quantitation of NHC and VER displayed excellent linearity over the concentration ranges of 50–1600 nmol/L for NHC and 10–250 nmol/L for VER. The limits of detection (LOD) and quantitation (LOQ) in rabbit plasma were found to be 15.2 and 50.8 nmol/L for NHC and 2.9 and 9.9 nmol/L for VER, respectively. Moreover, fundamental pharmacokinetic parameters were calculated for NHC before and after co-administration of VER. The results suggest that the SWV method using CuTCNQ-modified CPE can be a useful tool for the determination of NHC and VER levels in plasma samples, with potential applications in the monitoring of drug-drug interactions involving carboxylesterase-2 inhibitors.

Characterization and Application of a Synthesized Novel Poly(chlorobis(1,10-phenanthroline)resorcinolcobalt(II) chloride)-Modified Glassy Carbon Electrode for Selective Voltammetric Determination of Cefadroxil in Pharmaceutical Formulations, Human Urine, and Blood Serum Samples.

Cefadroxil belongs to the β-lactam antibiotics, mainly used for the treatment of various bacterial infections, caused by Gram-positive and Gram-negative bacteria. However, it is also encountering serious bacterial resistance, necessitating continuous monitoring of its level in pharmaceutical and biological samples. This study presents a selective, accurate, and precise square-wave voltammetric method based on a novel poly(chlorobis(1,10-phenanthroline)resorcinolcobalt(II)chloride)-modified glassy carbon electrode (poly(CP2RCoC)/GCE) for determination of cefadroxil (CDL). UV-vis spectroscopy, FT-IR spectroscopy, metal and halide estimation, CHN elemental analysis, and electrolytic conductivity measurement results confirmed the synthesis of the title complex modifier. Electrode characterization results revealed modification of the surface of the electrode by an electroactive and a conductive polymer film (poly(CP2RCoC)/GCE), leading to an improved effective electrode surface area. In contrast to the bare electrode, the appearance of an irreversible oxidative peak at a much reduced potential with a 7-fold current enhancement at poly(CP2RCoC)/GCE showed the catalytic effect of the modifier toward oxidation of CDL. The square-wave voltammetric current response of poly(CP2RCoC)/GCE showed a linear dependence on the concentration of CDL in the range of 1 × 10-7-3.0 × 10-4 M with a detection limit of 4.3 × 10-9. The CDL level in the selected two tablet brands was in the range of 97.25-100.00% of their labeled values. The spike recovery results in tablet, human blood serum, and urine samples were 98.85-101.30, 99.20-100.39, and 98.10-99.99%, respectively. Interference recovery results with a less than 4.74% error, lower LoD, and wider dynamic range than the previously reported methods validated the potential applicability of the present method with excellent accuracy and sensitivity based on the novel mixed-ligand complex-modified GCE (poly(CP2RCoC)/GCE) for determination of CDL in various real samples with a complex matrix.

Investigation of the electrochemical properties of benzo[k]fluorenthene using a glassy carbon electrode and development of a square-wave voltammetric method for its quantification

Investigation of the electrochemical properties of benzo[k]fluorenthene using a glassy carbon electrode and development of a square-wave voltammetric method for its quantification

Ultrasensitive Electrochemical Sensor Based on SnO2 Anchored 3D Porous Reduced Graphene Oxide Nanostructure Produced via Sustainable Green Protocol for Subnanomolar Determination of Anti-Diabetic Drug, Repaglinide

Herein, we have reported on a simple, environmentally friendly, and ultra-sensitive electrode material, SnO2@p-rGO, used in a clean sustainable manner for rapid electrochemical determination of an anti-diabetic agent, repaglinide (RPG). Three-dimensional porous reduced graphene oxide nanostructure (p-rGO) was prepared via a low-temperature solution combustion method employing glycine. The aqueous extract of agricultural waste “cotton boll peel” served as stabilizing and reducing agents for the synthesis of SnO2 nanoparticles. The structural and morphological characterization was carried out by XRD, Raman, SEM, EDX, FTIR, absorption, and TGA. The oxidation process of RPG was realized under adsorption controlled with the involvement of two protons and electrons. The sensor displayed a wider linearity between the concentration of RPG and oxidation peak current in the ranges of 1.99 × 10−8–1.45 × 10−5 M and 4.99 × 10−8–1.83 × 10−5 M for square-wave voltammetric and differential pulse voltammetric methods, respectively. The lower limit of detection value of 0.85 × 10−9 M was realized with the SWV method. The proposed sensor was applied for the quantification of RPG in fortified urine samples and pharmaceutical formulations. Furthermore, the sensor demonstrated reproducibility, long-term stability, and selectivity in the presence of metformin and other interferents, which made the proposed sensor promising and superior for monitoring RPG.

A novel mesna-based electrochemical sensor embellished with silver nanoparticles for ultrasensitive analysis of modafinil.

Modafinil (MOD) is a CNS stimulant used for the treatment of narcolepsy, shift work sleep disorder, excessive daytime sleepiness, and post-COVID 19 neurological symptoms. In the literature, there is no report of square wave voltammetric (SWV) methods being used for the determination of MOD. This study describes, for the first time, the construction and evaluation of the analytical performance of a novel sensor for ultrasensitive SWV detection of MOD. The sensor was constructed by integration of silver nanoparticles (AgNPs) on Mesna (MSN) layers over a pencil graphite electrode (PGE) surface. The interface and morphological characteristics of the fabricated AgNPs@MSN/PGE sensor were investigated via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). This sensor was found to enhance the electro-oxidation of MOD. The combination of AgNPs@MSN/PGE with SWV enabled the determination of MOD in its bulk form and in pharmaceutical and biological matrices at the nanomolar scale (LOD = 28.59 nM) with excellent recoveries. This study represents the first report describing an electrochemical procedure for MOD detection in human plasma. The established SWV method was also validated, and the results were consistent with ICH criteria. Finally, the presented SWV procedure provides a facile, sensitive, rapid, and cost-effective approach compared to other existing methods.

Comparative study of boron-doped diamond, basal-plane pyrolytic graphite, and graphite flake paste electrodes for the voltammetric determination of rivaroxaban and dabigatran etexilate in pharmaceuticals and urine samples

As anticoagulants, rivaroxaban (RIV) and dabigatran etexilate (DAB) are high-risk drugs that can cause life-threatening bleeding. They are a group of drugs that require optimal dosing, therefore their monitoring in the patient is of great importance, especially in emergencies. In this study, we developed a rapid, sensitive square-wave voltammetric (SWV) method by using boron-doped diamond, graphite flake paste, and basal-plane pyrolytic graphite electrodes (BDDE, GFPE, and BPPGE, respectively) to determine the presence of anticoagulants, namely, RIV and DAB in pharmaceutical and urine samples. The supporting electrolyte composition and SWV parameters were investigated. The sensitivity, stability, recovery, calibration curve, and limit of detection (LOD) of the developed method were evaluated. Under the optimal experimental condition, a wider linear response was achieved using BDDE in the detection of both RIV and DAB. The calibration curve for RIV was in the range of 0.5–30.0 μmol L−1 for BDDE and 1.0–10.0 μmol L−1 for GFPE. The calibration curve for DAB was in the range of 0.01–0.7 μmol L−1 for BDDE and 0.07–1.0 μmol L−1 for BPPGE, which shows a linear relationship between the concentration of DAB and the anodic current. LOD was equal to 0.145 μmol L−1 (for RIV at BDDE), 0.297 μmol L−1 (for RIV at GFPE), 2.78 nmol L−1 (for DAB at BDDE), and 16.7 nmol L−1 (for DAB at BPPGE). Finally, BDDE, GFPE, and BPPGE were applied to detect the presence of RIV and DAB in pharmaceuticals and spiked urine samples with satisfactory results (98.2–100.5% for RIV and 99.22–102.8% for DAB). Cyclic voltammetry (CV) was applied to understand the electrode mechanism of RIV and DAB oxidation. The character of RIV and DAB signals was irreversible and diffusion-controlled. In addition, the roughness factor (RF) of BDDE, GFPE, and BPPGE was investigated, which were equal to 0.367, 0.558, and 0.422, respectively.

Boron-doped diamond film and multiple linear regression-based calibration applied to the simultaneous electrochemical determination of paracetamol, phenylephrine hydrochloride, and loratadine in fixed-dose combinations

In this work, we employed multiple linear regression analyses to satisfactorily determine cold symptoms treatment drugs paracetamol, phenylephrine hydrochloride, and loratadine in pharmaceutical formulations with combined dosage and spiked human urine sample. All the drugs are irreversibly oxidized on the boron-doped diamond electrode (BDDE) in diffusion-controlled oxidation processes with well-separated potentials in acidic media. A square-wave voltammetric (SWV) method was developed for their simultaneous determination in 0.1 mol L–1 H2SO4 and simple and multiple linear regression analyses were compared as calibration methods for SWV data. Precision and selectivity were also studied. The high concentration ratio between paracetamol and the other two drugs being minor components in the formulated dosage forms caused interference in their voltammetric responses. An assay based on multiple linear regression equations considering these multiple effects revealed statistically the same results as those obtained by a comparative HPLC-UV method at a 95% confidence level. We demonstrated that multiple linear regression provided adequate recovery for the determination of PAR, PHE, and LOR in spiked human urine sample. The developed SWV method is a very fast, low-cost, and environmentally friendly alternative to the routine simultaneous analysis of PAR, PHE, and LOR performed by HPLC-UV.

Determination of methylisothiazolinone in waters. Comprehensive study about electrochemical behaviour on gold electrode and optimization of square-wave voltammetric methods

Abstract Methylsiothiazolinone (MIT) is a wide spectrum biocide used in different industrial fields. In this paper, the electrochemical behaviour of MIT on gold electrode has been studied and square wave voltammetric methods have been developed to determine this compound at different concentration levels. MIT exhibited and irreversible and diffusion- controlled oxidation process with potential and peak current values pH dependent. This biocide can be determined by square-wave voltammetry (SWV) with a linear response up to 53 mg L−1. Using an adsorptive stripping approach prior to the square-wave voltammetry (SWAdSV) it is possible to analyse samples containing very low concentrations of MIT, with a limit of detection of 0.0080 mg L−1. Both SWV and SWAdSV methods were applied with successful results to determine MIT in different water samples.

Voltammetric determination of creatinine using a gold electrode modified with Nafion mixed with graphene quantum dots-copper

Creatinine levels in blood and urine can be used as an important biomarker for the diagnosis of renal, thyroid, and muscle malfunctions. In this work, a square-wave voltammetric method for creatinine was developed using a gold electrode modified with a film composed by Nafion mixed with a graphene quantum dots dispersion prepared in the presence of Cu 2+. Such Au/Nafion-GQDs-Cu electrode relies on the interactions of creatinine with Cu 2+ released from the oxidation of Cu thus decreasing the characteristic Cu/Cu 2+ anodic peak at +350 mV. A linear response was obtained for the analyte in the concentration range from 1.0 × 10 −6 mol L −1 (0.11 mg L −1 ) to 4.5 × 10 −4 mol L −1 (50.9 mg L −1 ). The proposed sensor was simple to prepare and the method was successfully applied for creatinine determination in urine samples. • Creatinine was determined using a Nafion-GQDs-Cu modified gold electrode. • Nanocomposite formed by graphene quantum dots modified with copper (GQDs-Cu). • Creatinine decreased the characteristic Cu/Cu 2+ signal of the modified electrode. • Limit of quantification was adequate for urine analysis.

Tetrabutylammonium Chloride Modified Carbon Paste Electrode for Rapid and Highly Sensitive Voltammetric Determination of Carbendazim

The voltammetric characterization and determination of fungicide carbendazim (methyl-1H-benzimidazol-2-yl-carbamate, CBZ) were performed using simple and highly sensitive electrochemical sensor based on tetrabutylammonium chloride (TBACl) ionic liquid as modifier of carbon paste electrode (CPE) and compared to conventional CPE in aqueous Britton-Robinson buffer solution as supporting electrolyte (pH 2.0–11.98). Cyclic voltammetric (CV) studies suggested that electrode reaction is mixed diffusion-adsorption controlled. Also, the square wave voltammetric (SWV) and square-wave adsorptive stripping voltammetric (SW-AdSV) methods were optimized for quantitation of CBZ. In the model solutions of pH 5.0, the linear calibration curves were obtained in CBZ concentration ranges from 2.5 to 280.0 ng ml−1 by SWV and from 1.5 to 40.0 ng ml−1 by SW-AdSV method (Eacc = −0.25 V, tacc = 180 s) with relative standard deviation lower than 2.0%. A great improvement in terms of CBZ electrochemical oxidation with low detection limit as 0.45 ng ml−1 was achieved using proposed highly sensitive SW-AdSV method. TBACl-CPE in combination with the optimized SWV and SW-AdSV methods was successfully applied for trace level determination of CBZ in spiked fruit juice and river water samples, respectively, with good recovery and reproducibility, demonstrating the reliability and accuracy of the developed methods.

Simultaneous Monitoring of Febuxostat and Uric Acid in Human Serum Samples Using the Direct Square-Wave Voltammetric Method

Background: High uric acid serum level, hyperuricemia, is now associated with many diseases such as gout, chronic kidney disease, hypertension, coronary artery disease and diabetes. Febuxostat is a novel selective xanthine oxidase inhibitor approved for the treatment of hyperuricemia. Objective: The aim of this study was to develop a first analytical method for the simultaneous determination of febuxostat and uric acid. Methods: An unmodified boron-doped diamond electrode provided concurrent quantitation of drug at low levels and uric acid, which has clinical significance in the diagnosis and therapy of hyperuricemia, at relatively high concentrations. The direct square-wave voltammetric method was applied to the analysis of both analytes in human serum samples. Results: Under the optimized conditions, the linear response of peak current on febuxostat concentration was achieved in the range from 7.5 × 10-7 to 3 × 10-5 M, while uric acid showed two linear ranges of 5 × 10-6 - 5 × 10-5 M and 5 × 10-5 - 2 × 10-4 M. The method was successfully utilised for quantification of both analytes in human serum samples. Good recoveries were obtained without interference from common inorganic cations and anions as well as glucose, dopamine, ascorbic and folic acids at concentrations expected in physiological conditions. Conclusion: The great benefits of developed method are fast analysis (only 7.5 s for run), low cost and simplicity of performance.

Electrochemical sensor for acetaminophen based on a glassy carbon electrode modified with ZnO/Au nanoparticles on functionalized multi-walled carbon nano-tubes

Recent years have witnessed unprecedented growth of research and applications in the monitor of acetaminophen (AP) in biological specimen and pharmaceuticals, as a salient area in public healthcare and medical services. The present study aimed at preparing a modified Glassy Carbon Electrode (GCE) with a facile, novel composite of Multi-Walled Carbon Nano-Tube (MWCNT)/ZnO/Au nanoparticles through electrochemical synthesis for AP determination. The nanocomposite was characterized by Field-Emission Scanning Electron Microscopy (FESEM). The results showed that Au nanoparticles were well anchored onto ZnO nanospheres embedded over MWCNTs. The modified electrode led to a nearly 47-fold increase in current response towards AP current compared to a bare electrode. Under optimum conditions, the electrode provided a linear response based on the AP concentrations between 0.05‐20 μM with a detection limit of 9 nM by using the Square-Wave Voltammetric (SWV) method. Also, it exhibited a good sensitivity and selectivity for the AP determination of in pharmaceutical samples.

A simple and fast-portable method for the screening of the appetite-suppressant drug sibutramine in natural products and multivitamins supplements

Sibutramine is one of the most widespread adulterants encountered in herbal formulations or dietary supplements used for weight-loss purposes. In this work, a simple and portable square-wave voltammetric (SWV) method was proposed for fast screening and quantification of sibutramine in herbal formulations and dietary supplements samples. The selective determination of sibutramine was possible using 0.1 mol L−1 H2SO4 solution as the supporting electrolyte and boron-doped diamond (BDD) as the working electrode. The screening of the samples is possible after a simple sample preparation procedure (dissolution in supporting electrolyte) and subsequent fast SWV scan with reliable indication of the presence or absence of sibutramine. Under optimized conditions, the determination of sibutramine is also possible with a linear working range from 5 to 50 mg L−1 (r > 0.99) and detection limits varying from 0.08 to 1.94 mg L−1 (depends on the type of sample). Moreover, it was demonstrated that the SWV developed method can be easily adapted to a portable batch-injection analysis (BIA) system aiming fast and on-site screening procedures.

NiO nanoparticle decorated on single-wall carbon nanotubes and 1-butyl-4-methylpyridinium tetrafluoroborate for sensitive raloxifene sensor

In this study, carbon paste electrode (CPE) modified with NiO/SWCNTs and 1-butyl-4-methylpyridinium tetrafluoroborate (1B4MPTFB) was used for the effective determination of raloxifene as a sensor. The use of NiO/SWCNTs and 1B4MPTFB in the electrode matrix showed great conductivity for electro-oxidation of raloxifene and nanomolar determination of raloxifene in buffering the solution. The CPE/NiO/SWCNTs/1B4MPTFB improved the oxidation current of raloxifene and reduced the oxidation overvoltage compared to an unmodified sensor. The CPE/NiO/SWCNTs/1B4MPTFB showed a linear dynamic range of 0.03–520 μM with a detection limit of 7.0 nM using the square-wave voltammetric method. The CPE/NiO/SWCNTs/1B4MPTFB showed good sensitivity for the analysis of raloxifene in table and pharmaceutical serum samples. The obtained data for real samples analysis were checked with other analytical method and statistical tests such as F-test and t-test were used for study the accuracy of data.

Analysis of glutathione in the presence of acetaminophen and tyrosine via an amplified electrode with MgO/SWCNTs as a sensor in the hemolyzed erythrocyte

In this study, we investigated the effect of adding MgO/SWCNTs and 2-Chloro-N′-[1-(2,5-dihydroxyphenyl) methylidene]aniline (2-CDHPMA) to a carbon paste matrix, which could act as a voltammetric sensor for the analysis of glutathione. The electrocatalytic interaction between 2-CDHPMA and glutathione was used as a factor for the analysis of this biological compound in real samples. In addition, the presence of MgO/SWCNTs can help in increasing the sensitivity of the fabricated sensor and for obtaining a low limit of detection in the analysis of glutathione. When the carbon-paste electrode was amplified with MgO/SWCNTs and 2-CDHPMA (CPE/MgO/SWCNTs/2-CDHPMA), it showed a good selectivity for the analysis of glutathione in the presence of acetaminophen and tyrosine with the separated peak potentials at ~ 280mV, ~ 570mV, and ~ 880mV for the first time. We detected a linear dynamic range between 0.05 and 700.0μmolL−1 with the limit of detection set at ~ 10 ± 0.3nmolL−1 for the analysis of glutathione by the square-wave voltammetric method. The CPE/MgO/SWCNTs/2-CDHPMA showed a high quality of detection of glutathione in the hemolyzed erythrocyte sample.

Electrochemical Characteristics and Electrosensing of an Antiviral Drug, Entecavir via Synergic Effect of Graphene Oxide Nanoribbons and Ceria Nanorods

AbstractA sensitive electrochemical sensor was fabricated based on ceria‐graphene oxide nanoribbons composite (CeO2‐GONRs) for an antiviral drug, entecavir (ETV). It was characterized by SEM, EDAX, AFM, IR and Raman spectroscopic techniques. The electrochemical behaviour of ETV was investigated by cyclic voltammetric, differential pulse voltammetric (DPV), linear sweep voltammetric (LSV) and square wave voltammetric (SWV) methods at CeO2‐GONRs modified glassy carbon electrode. Good linearity was observed between the peak current and concentration of ETV in the range of 0.51 ‐ 100 μM with a detection limit of 0.042 μM in DPV method, 2.1 – 61.1 μM with a detection limit of 0.7 μM in LSV method and 0.1 ‐ 80 μM with a detection limit of 68.1 nM in SWV method. The proposed sensitive DPV method was successfully applied for the determination ETV in tablets and biological samples.

Voltammetric behavior and determination of the macrolide antibiotics azithromycin, clarithromycin and roxithromycin at a renewable silver – amalgam film electrode

The renewable silver-amalgam film electrode (Hg(Ag)FE) was applied for voltammetric characterization and determination of semi-synthetic macrolide antibiotics azithromycin (AZI), clarithromycin (CLA) and roxithromycin (ROX) in the Britton-Robinson buffer as supporting electrolyte ranging the pH from 4.0 to 11.9. All three macrolides showed reduction signals in fairly negative potential range.During direct cathodic square wave voltammetric (SWV) investigations conducted over the potential range from −0.75V to −2.00V vs SCE, either one or two reduction peaks were obtained in the potential range from −1.5 to −1.9V. The shapes and intensities of the signals depend on the applied pH values in wider pH ranges. For analytical purposes concerning the development of direct cathodic SWV and adsorptive stripping SWV (SW-AdSV) methods the neutral and slightly alkaline media were suitable as pH 7.2, pH 7.4 and pH 7.0 for AZI, CLA and ROX, respectively. Based on the cyclic voltammograms recorded at these pH values, adsorption-controlled electrode kinetics process can be proposed for all three macrolides. Furthermore, the water suppressed 1H NMR measurements in the pH range between 6.0 and 10.5 indicated that the macrolide molecules at the optimal analytical conditions are predominantly in protonated form via their tertiary amino groups which supported in all three cases their adsorption on the appropriately polarized Hg(Ag)FE electrode. The optimized direct cathodic SWV methods showed good linearity in concentration ranges 4.81–23.3μgmL−1, 1.96–28.6μgmL−1 and 1.48–25.9μgmL−1 for AZI, CLA and ROX, respectively. The development of the SW-AdSV methods resulted in the linear responses at lower concentration ranges as 1.0–2.46μgmL−1, 0.05–0.99μgmL−1 and 0.10–0.99μgmL−1, for AZI, CLA and ROX, respectively. The relative standard deviation for all developed methods was not higher than 1.0% except the SWV method for AZI with 4.7%. In the case of all three investigated macrolide antibiotics the protonated form of the tertiary amino group(s) at appropriate accumulation potential and time favored the adsorption of the ionic form of the target molecules offering the opportunity for the development of SW-AdSV methods for their trace level analysis on Hg(Ag)FE. Optimized SW-AdSV method was applied for determination of ROX in pharmaceutical preparation Runac®.

Electrochemical Sensor Based on Reduced Graphene Oxide Nanoribbons for the Determination of Baicalein in Urine Samples

Electrochemically reduced graphene oxide nanoribbons (ErGONRs) have been prepared, characterized and utilized for sensing of a flavone, baicalein (BAI) by adsorptive stripping differential pulse voltammetric (AdSDPV) and square wave voltammetric (SWV) methods. BAI showed redox peaks (Epa = 0.582 V and Epc = 0.557 V) and an irreversible oxidation peak at 1.402 V on ErGONRs/GCE in phosphate buffer of pH 3. A 50-fold enhanced electrochemical response was observed at ErGONRs/GCE for BAI when compared to that noticed at bare GCE. The parameters concerning the electrochemical behavior of BAI were carefully optimized. Under optimized conditions, SWV and AdSDPV methods showed linearity in the range of 10 nM–87.4 μM and 0.4 μM–50 μM, respectively. Applicability of the proposed electrode was demonstrated by determining BAI in urine samples