Voltammetric Determination Of Ascorbic Acid Research Articles

Zirconium oxide-porous carbon derived from metal-organic frameworks as a new sensing platform: application to simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid

Zirconium oxide-porous carbon derived from metal-organic frameworks as a new sensing platform: application to simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid

A New Method for the Determination of Total Content of Vitamin C, Ascorbic and Dehydroascorbic Acid, in Food Products with the Voltammetric Technique with the Use of Tris(2-carboxyethyl)phosphine as a Reducing Reagent

The objective of the study was to develop a new method for the determination of the total content of vitamin C and dehydroascorbic acid in food, based on the technique of differential pulse voltammetry with the use of a boron-doped diamond electrode modified with mercury film. A comparison was made between the results obtained with the developed method and a proposed reference method based on high-performance liquid chromatography with spectrophotometric detection. The reduction of dehydroascorbic acid was performed with the use of tris(2-carboxyethyl)phosphine. The interference caused by the presence of tris(2-carboxyethyl)phosphine during the voltammetric determination of ascorbic acid was effectively eliminated through a reaction with N-ethylmaleimide. The conducted validation of the voltammetric method indicated that correct results of analysis of the total content of vitamin C and ascorbic acid were obtained. Analysis of the content of dehydroascorbic acid was imprecise due to the application of the differential method. The results of the analyses and the determined validation parameters of the developed method are characterised by a high degree of conformance with the results obtained with the chromatographic reference method, which indicates the equivalence of the two methods.

Multifunctional Porous Films Based on Polylactic Acid/Polycaprolactone Blend and Graphite Nanoplateles

The aim of this work was to develop polylactic acid (PLA) based porous films with suitable properties to be used as sensors and absorbers. The formulation was designed to make the films porous, ductile, and conductive and characterized by surface functionalization. The phase inversion method was used to impart porosity to the polymer film. Polycaprolactone (PCL) and graphite, in the form of graphite nanoplatelets (GNP), were added to increase the elongation at break of the polymer matrix and to make the systems conductive, respectively. To optimize the formulation, the effect of polymer concentration in the initial solution on the viscosity, porosity, and morphology was investigated. FE-SEM measurements showed that the phase inversion method allowed limiting the aggregation of both PCL domains and GNP, whose flakes were found to adhere well to the polymer matrix and to have a nucleating effect, as evidenced by DSC measurements. A simple aminolysis reaction was performed using a diamine, i.e., ethylenediamine, to generate surface amino functionalities. In particular, the extent of functionalization as a function of reaction time was investigated by using FT-IR spectroscopic measurements. By combining these results with the stability of the polymer film, which tends to lose its structural integrity due to the erosion caused by the aminolysis reaction, the optimal contact time with the aqueous solution of ethylenediamine was found. Mechanical measurements showed that the presence of PCL increased the elongation at break of films by 3 times compared to neat PLA. Finally, the films developed starting from the optimized formulations based on PLA/PCL blends, containing GNP and surface functionalized, proved to be effective electrodes for the voltammetric determination of ascorbic acid. In addition, it is of utmost relevance that both amino functionalization and GNP conferred high capacity to the films to retain fluorescein, a model dye.

Simultaneous voltammetric determination of ascorbic acid and acetaminophen in pharmaceutical formulations with UiO-66-modified glassy carbon electrode

Simultaneous voltammetric determination of ascorbic acid and acetaminophen in pharmaceutical formulations with UiO-66-modified glassy carbon electrode

Synthesis, characterization and electrochemical sensors application of MnO2 nanoparticles

The prepared MnO2 nanoparticles were characterized through electronic spectroscopy. The band gap value of nanoparticles is 3.12 eV. The stretching vibration band of nanoparticles of MnO2 at 631 cm−1 can be assigned to Mn–O. The manganese oxide nano flower–like structure, proved through atomic force microscopy (AFM) photographic studies. The MnO2 morphology was confirmed uniform coating on the electrode surface. Glassy carbon electrode (GCE) was modified with manganese oxide nanoparticles to enhance the electrocatalytic activity of the redox behavior of ascorbic acid. The oxide nano flower modified electrode is used as fresh voltammetric determination of ascorbic acid. The results of voltammetric behavior are satisfactory in the electro oxidation of ascorbic acid, and exhibit considerable improvement compared to glassy carbon electrode. Under the optimized experimental conditions, the modified electrode exhibit better linear dynamic range from 50 μg/L to 500 μg/L with lower limit of detection 30 μg/L for the stripping voltammetric determination of ascorbic acid. The real sample solution of ascorbic acid was successfully applied for accurate determination of trace amounts on nanomaterials modified electrode.

Voltammetric determination of ascorbic acid using carbon paste electrode in ginger samples from selected areas of Ethiopia

Carbon paste electrode was prepared for the determination of ascorbic acid in ginger (Zingiber officinale) samples from three ginger growing areas (Chilga, Tepi and Dale Sadi) in Ethiopia. The effect of pH on the oxidation response of ascorbic acid in 0.1 M phosphate buffer was investigated and pH 2 was chosen as an optimum value. The oxidation response of ascorbic acid was predominantly diffusion-controlled reaction with a better determination coefficient R2= 0.9945 on the plot of anodic peak current vs square root of scan rate. A square wave amplitude of 45 mV, step potential of 7.0 mV and frequency of 25 Hz were chosen as optimum values. Linear calibration curve in the range of 0.1 – 8.0 mM of ascorbic acid standard in pH 2 phosphate buffer solution was obtained with a determination coefficient of 0.998. The amount of ascorbic acid detected in ginger samples collected from the three areas, Chilga was 6.85, Tepi was 6.59 and Dale Sadi was 6.54 mg/g of ginger powder. Percentage recovery in the range of 93% and 100% was validated for the applicability of the method for the quantitative determination of ascorbic acid in ginger samples. According to Health Canada dietary reference intakes, the maximum amount of ginger powder recommended intake for adult males in Chilga was 13.1, in Tepi 13.7 and in Dale Sadi 13.8 g/day.

Simultaneous voltammetric determination of ascorbic acid and its derivatives in cosmetics using epoxy-carbon composite electrodes

We used a voltammetric method to determine the levels of ascorbic acid (AA) and two AA derivatives (magnesium ascorbyl phosphate (MAP) and ascorbyl palimitate (AP)) in cosmetic products. These compounds are believed to affect the process of skin aging and are widely used in skin care products. An electrode composed of an epoxy resin and graphite powder can be easily fabricated. We studied the effects of solutions' pH and different supporting electrolytes on the performance of a carbon-epoxy electrode which we used as a working electrode to take voltammetric measurements that would quantify the levels of AA, MAP and AP in various cosmetic products effectively. In the voltammogram, anodic peak potentials of AA, MAP and AP were obtained at about 0.35 ± 0.07, 0.81 ± 0.11, and 0.23 ± 0.03 volts in various pH and different supporting electrolytes respectively. Linearity of peaks from plots of current vs. concentration (correlation coefficient r2 > 0.997) was over the range of 10-300 μg/mL for all analytes. The limits of detection (LOD) for AA, AMP and AP were lower than 0.17, 0.46 and 0.09 μg/mL respectively. For the three analytes in cosmetic formulations, the relative standard deviations were below 6.3%, and the range of recovery ratio ranged from 92.2 to 104.5%. Various compounds coexisting in the formulations that were potential sources of organic interferences in voltammetric analysis were explored. Ascorbic acid oxidizes easily to dehydroascorbic acid, but its derivatives are relatively stable. Material instability could result in a significant error in the analytical method. Different approaches were used to inhibit ascorbic acid degradation, and purge of oxygen from the analyzed solution with nitrogen was found to be the most effective method.

Simultaneous voltammetric determination of ascorbic acid, dopamine, acetaminophen and tryptophan based on hybrid trimetallic nanoparticles-capped electropretreated graphene

A novel nanocomposite sensor based on trimetallic nanoparticles of (Au/Ag/Pd)NPs uniformly capped electropretreated graphene oxide (EPGrO) was fabricated. The investigation and characterization of the (Au/Ag/Pd)NPs/EPGrO nanocomposite were studied by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) techniques. Cyclic voltammograms (CVs) of the nanocomposite electrode displayed obvious and sharp oxidation peaks for each ascorbic acid (AA), dopamine (DA), acetaminophen (AP) and tryptophan (TP) as compared to their responses at EPGrO and bare electrodes. An efficient electron mediating behavior of the nanocomposite electrode with large separation peak potentials for AA–DA, DA–AP, and AP–TP were estimated to be 0.16, 0.18 and 0.29 V, respectively. In addition, differential pulse voltammograms (DPVs) of the nanocompsite electrode showed simultaneous determination of AA, DA, AP and TP with linear calibration plots from 5–650 μM, 1–700 μM, 5–700 μM and 1–600 μM where their detection limits were calculated to be 0.24 ± 0.03, 0.02 ± 0.01, 0.12 ± 0.04 and 0.03 ± 0.01 μM, respectively. Finally, the practical application of the (Au/Ag/Pd)NPs/EPGrO nanocomposite electrode was successfully conducted for the analytical determination of AA, DA, AP and TP in real sample of human blood serum.

Electrochemical behaviour and analytical applications of a manganese porphyrin – silica hybrid film prepared by pulsed laser deposition

Hybrid nanomaterials can have superior properties in comparison with individual components, sometimes greatly improving their optoelectronic activity. For this reason, modified carbon electrodes were obtained using a hybrid material composed of 5,10,15,20-tetra(4-tolyl)porphyrinato manganese (III) chloride (MnTTP) embedded in a silica matrix. The laser ablation deposition technique (PLD) has been used to immobilize the manganese porphyrin–silica hybrid on the surface of the carbon electrodes. The successful transfer of the manganese-porphyrin was evidenced by UV–Vis absorption spectroscopy. The PLD-deposited hybrid film was characterized using AFM and electrochemical methods (cyclic voltammetry and square wave voltammetry). The viability of this hybrid nanomaterial film as a redox mediator for the anodic oxidation and sensitive voltammetric determination of ascorbic acid in buffer solution (pH = 6.5) is described. The recorded anodic process is attributed to its oxidation to dehydroascorbic acid, with satisfactory catalytic current response and low non-Faradaic current.

A mesoporous silver-doped TiO2-SnO2 nanocomposite on g-C3N4 nanosheets and decorated with a hierarchicalcore-shell metal-organic framework for simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid.

An electrochemical sensor is described for the simultaneous voltammetric determination of ascorbic acid (AA), dopamine (DA), anduric acid (UA). An indium-tin oxide (ITO) electrode was modified with a hierarchical core-shell metal-organic framework and Ag-doped mesoporous metal-oxide based hybrid nanocomposites on g-C3N4 nanosheets. The morphology, structural and chemical composition of the hybrid nanocomposite was characterized using different analytical methods. The modified ITO showed superior electrocatalytic performance towards the oxidation of AA, DA and UA due to the enhanced surface area, synergistic effects and well-organized porous assembly. Figures of merit, include (a) linear responses from 0.1 to 200μM, 2.5 to 100μM and 2.5 to 625μM; (b) detection limits (at S/N= 3) of 0.02, 0.01 and 0.06μM, and (c) well separated oxidation peaks near -50, 186 and 390mV (vs. Ag/AgCl) for simultaneous sensing AA, DA and UA, respectively. The sensor was evaluated by analysing spiked serum samples and gave data with precision, with recoveries of >98%. Graphical abstractSchematic Representation of a Mesoporous Silver-doped TiO2-SnO2 Nanocomposite (h-ATS) on g-C3N4 Nanosheets and Decorated with a HierarchicalCore-Shell Metal-Organic Framework (NC@GC) Based Electrochemical Sensor for Simultaneous Voltammetric Detection of Ascorbic acid, Dopamine and Uric acid.

Electrodeposited poly(3,4-ethylenedioxythiophene) doped with graphene oxide for the simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid.

Poly(3,4-ethylenedioxythiophene) (PEDOT) films were electrodeposited by cyclic voltammetry on aglassy carbon electrode (GCE) in aqueous solution. Three kinds of supporting electrolytes were used, viz. graphene oxide (GO), phosphate buffered saline (PBS), and GO in PBS, respectively. The surface morphology of the modified electrodes was characterized by scanning electron microscopy. The electrochemical performance of the modified electrodes was investigated by cyclic voltammetry and electrochemical impedance spectroscopy by using the hexacyanoferrate redox system. The results demonstrate that the PEDOT-GO/GCE, which was electropolymerized in aqueous solutions containing EDOT and GO, shows the best electrochemical activities compared with other modified electrodes. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were investigated by cyclic voltammetry. The PEDOT-GO/GCE exhibits enhanced electrocatalytic activities towards these important biomolecules. Under physiological pH conditions and in the mixed system of AA, DA and UA, the modified GCE exhibits the following figures of merit: (a) a linear voltammetric response in the concentration ranges of 100-1000μM for AA, 6.0-200μM for DA, and 40-240μM for UA; (b) well separated oxidation peaks near 31, 213 and 342mV (vs. saturated Ag/AgCl) for AA, DA and UA, respectively; and (c) detection of limits (at S/N = 3) of 20, 2.0 and 10μM. The results demonstrate that GO, based on its relatively large number of anionic sites, can be used as the sole weak electrolyte and charge balance dopant for the preparation of functionally doped conducting polymers by electrodeposition. Graphical abstractSchematic representation of a nanostructure composedof hybrid conducting polymer PEDOT-GO nanocomposites, and its application to simultaneous determination of ascorbic acid, dopamine and uric acid.

Copper Nanowires Modified with Graphene Oxide Nanosheets for Simultaneous Voltammetric Determination of Ascorbic Acid, Dopamine and Acetaminophen.

Copper nanowires (Cu NWs) were modified with graphene oxide (GO) nanosheets to obtain a sensor for simultaneous voltammetric determination of ascorbic acid (AA), dopamine (DA) and acetaminophen (AC). The nanocomposite was obtained via sonication, and its structures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The electrochemical oxidation activity of the materials (placed on a glassy carbon electrode) was studied by cyclic voltammetry and differential pulse voltammetry. Due to the synergistic effect of Cu NWs and GO, the specific surface, electrochemical oxidation performance and conductivity are improved when compared to each individual component. The peaks for AA (−0.08 V), DA (+0.16 V), and AC (+0.38 V) are well separated. The sensor has wide linear ranges which are from 1–60 μM, 1–100 μM, and 1–100 μM for AA, DA, and AC, respectively, when operated in the differential pulse voltammetric mode. The detection limits are 50, 410 and 40 nM, respectively. Potential interferences by uric acid (20 μM), glucose (10 mM), NaCl (1 mM), and KCl (1 mM) were tested for AA (1 μΜ), DA (1 μΜ), and AC (1 μΜ) and were found to be insignificant. The method was successfully applied to the quantification of AA, DA, and AC in spiked serum samples.

Voltammetric determination of ascorbic acid with zinc oxide modified glassy carbon electrode

Zinc oxide (ZnO) nanostructures electrodeposited from aqueous zinc nitrate solution at 70 °C onto glassy carbon electrode (GCE) were used as electrochemical detectors. The morphology, structure, chemical composition and conductivity of the as-deposited layers were determined using scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray analysis and UV–Vis spectroscopy. A highly oriented crystalline ZnO deposit made of a dense array of randomly oriented hexagonal nanorods was obtained without any additives in solution. The electrocatalytic oxidation of ascorbic acid (AA) was studied using cyclic voltammetry in 0.1 M phosphate buffer solution at pH 6.8. Comparing the response for AA oxidation on the bare and modified electrodes, the peak potential was shifted to − 0.45 V on ZnO/GCE with higher current densities and transfer coefficient, due to a simultaneous increase in oxidation rate and surface area. A linear relationship was determined between the anodic peak current and the AA concentration in the range of 0.1–5 mM.

In-situ growth of gold nanoparticles on a 3D-network consisting of a MoS2/rGO nanocomposite for simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid.

A glassy carbon electrode was modified with a 3D-networked nanostructure composed of MoS2, reduced graphene oxide and gold nanoparticles (3D-MoS2/rGO/Au). The composites were prepared through in-situ growth of gold nanoparticles on 3D-MoS2/rGO nanosheets via a hydrothermal method. The morphology and electrochemical features of the composite were investigated. The 3D-MoS2/rGO/Au sensor exhibits excellent electrocatalytic activity for simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The oxidation potentials are well separated at around -0.05V for AA, 0.06V for DA and 0.2V for UA, respectively. The detection limits for individual detection and simultaneous detection (S/N = 3) are 0.93μM and 1.46μM for AA, 0.11μM and 0.15μM for DA, and 0.74μM and 0.29μM for UA. The method was applied to the quantitative analysis of AA, DA, and UA in spiked serum samples with satisfying results. Graphical abstract In-situ growth of gold nanoparticles on 3D-networked MoS2/rGO nanocomposite for individual and simultaneous determination of ascorbic acid, dopamine and uric acid.

Gold nanorods decorated with graphene oxide and multi-walled carbon nanotubes for trace level voltammetric determination of ascorbic acid.

An ultra-sensitive sensor is described for the voltammetric determination of ascorbic acid (AA). A glassy carbon electrode (GCE) was modified with graphene oxide (GO), multi-walled carbon nanotubes (MWCNTs) and gold nanorods (AuNRs). GO was used to prevent the aggregation of MWCNTs. The integration of positively charged AuNRs reduces the overpotential and increases the peak current of AA oxidation. Figures of merit of this sensor, typically operated at a low working potential of 0.036V (vs. Ag/AgCl), include a low detection limit (0.85nM), high sensitivity (7.61μA·μM-1·cm-2) and two wide linear ranges (from 1nM to 0.5μM and from 1μM to 8mM). The use of GO simplifies the manufacture and results in a highly reproducible and stable sensor. It was applied to the quantification of AA in spiked serum. Graphical abstract Graphical abstract contains poor quality and small text inside the artwork. Please do not re-use the file that we have rejected or attempt to increase its resolution and re-save. It is originally poor, therefore, increasing the resolution will not solve the quality problem. We suggest that you provide us the original format. We prefer replacement figures containing vector/editable objects rather than embedded images. Preferred file formats are eps, ai, tiff and pdf.We have provided the original format with the attachments named g.tif. Graphene oxide (GO) in combination with multiwalled carbon nanotubes (MWCNTs) and gold nanorods (AuNRs) were used to constructa sensing interface with outstanding electrocatalytic performance for ascorbic acid detection.

Sonication-assisted preparation of a nanocomposite consisting of reduced graphene oxide and CdSe quantum dots, and its application to simultaneous voltammetric determination of ascorbic acid, dopamine and uric acid.

Cadmium selenide quantum dots were capped with reduced graphene oxide that was modified with thioglycolic acid. The nanocomposite was prepared by 5-min sonication of a solution of graphene oxide, thioglycolic acid, and cadmium(II) nitrate and selenium powder in the presence of NaBH4. X-ray diffraction and transmission electron microscopy were used to characterize the nanocomposite. A glassy carbon electrode (GCE) was modified with this nanocomposite and used for simultaneous determination of dopamine (DA), ascorbic acid (A) and uric acid (UA). The modified GCE was characterized by using cyclic voltammetry and differential pulse voltammetry. Simultaneous determination of AA, DA and UA was accomplished at working voltages of -50, +148 and + 280mV (all vs. Ag/AgCl), respectively. The voltammetric response to DA is linear in the 4.9 to 74.0μM concentration range, and the detection limit (defined as 3σ of the blank) is 0.11μM. The respective data are 0.39-1.0mM and 66μM for AA, and 9.0 to 120.0μM and 0.12μM for UA. The electrode was successfully applied to the determination of the 3 species in spiked urine samples. Graphical abstract Graphical abstract contains poor quality of text in image. Otherwise, please provide replacement figure file.Thank you for your comment. New garaphical abstract was attached. A sonochemical method was applied for synthesizing reduced graphene oxide decorated thioglycolic acid capped cadmium selenide quantum dots. A modified glassy carbon electrode was prepared for simultaneous determination of ascorbic acid, dopamine and uric acid.

Copper polydopamine complex/multiwalled carbon nanotubes as novel modifier for simultaneous electrochemical determination of ascorbic acid, dopamine, acetaminophen, nitrite and xanthine

In this study, a novel modified glassy carbon electrode with copper polydopamine complex/multiwalled carbon nanotubes (GCE/Cu2+@PDA-MWCNTs) was fabricated and used for voltammetric determination of ascorbic acid (AA), dopamine (DA), acetaminophen (AC), nitrite (Nit), and xanthine (XN). Different techniques such as field emission electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and electrochemical impedance spectroscopy were performed for characterization of the GCE/Cu2+@PDA-MWCNTs. Different electrochemical methods such as cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry (DPV) methods were employed to study the behavior of AA, DA, AC, Nit, and XN on this proposed modified electrode. The proposed modified electrode displays intense and indelible electrooxidation response for simultaneous determination of AA, DA, AC, Nit, and XN to five well-separated peaks in the potential range from 0.1 to 1.1 V using CV and DPV methods in phosphate buffer solution with pH 2.0. Under the optimum conditions, the calibration curves were liner up to 175, 125, 75, 150, and 115 μM with detection limits of 0.82, 0.45, 0.87, 0.92, and 0.67 μM for AA, DA, AC, Nit, and XN, respectively. This sensor was used to successfully determine these compounds in human urine and serum samples.

A composite consisting of microporous carbon and cobalt(III) oxide and prepared from zeolitic imidazolate framework-67 for voltammetric determination of ascorbic acid.

A nanoporous carbon/cobalt oxide (NPC/Co3O4) composite was synthesized from a single-precursor (zeolitic imidazolate framework-67). Transmission electron microscopy showed that the Co3O4 nanoparticles with an average particle size of 10nm (±2nm) were well dispersed in the NPC matrix. However, in a few places, Co3O4 nanoparticles were aggregated. The composite shows outstanding performance in terms of electrooxidation of ascorbic acid (AA) in phosphate buffer of pH7.0. The differential pulse voltammetric response of the composite electrode (at 0.12V vs. SCE) is linear in the 2-240μM AA concentration range, with a 20nM detection limit. The electrode exhibits high sensitivity (0.13μA·μM·cm-2), reliable reproducibility, and good selectivity. The method, when applied to the direct determination of AA in vitamin C tablets, gave recoveries between 98.0and102.0%. Graphical abstract A nanoporous carbon composite decorated with Co2O3 nanoparticles was prepared from a single precursor (the zeolitic imidazolate framework-67). It shows outstanding performance in terms of electrooxidation of ascorbic acid with high sensitivity (0.13μA·μM·cm-2), reliable reproducibility, and good selectivity.

De-bundled single-walled carbon nanotube-modified sensors for simultaneous differential pulse voltammetric determination of ascorbic acid, dopamine, and uric acid

De-bundled SWCNTs modified glassy carbon electrode for the simultaneous differential pulse voltammetric determination of ascorbic acid, dopamine, and uric acid.

An electrochemical sensor based on reduced graphene oxide decorated with polypyrrole nanofibers and zinc oxide–copper oxide p–n junction heterostructures for the simultaneous voltammetric determination of ascorbic acid, dopamine, paracetamol, and tryptophan

A three-dimensional porous nanocomposite was fabricated and used for the simultaneous voltammetric determination of ascorbic acid, dopamine, paracetamol, and tryptophan.