Electrochemical Behavior Of Ascorbic Acid Research Articles

Electrochemical determination of ascorbic acid using palladium supported on N-doped graphene quantum dot modified electrode

To precise screening concentration of ascorbic acid (AA), a novel electrochemical sensor was prepared using palladium nanoparticles decorated on nitrogen-doped graphene quantum dot modified glassy carbon electrode (PdNPs@N-GQD/GCE). For this purpose, nitrogen doped GQD nanoparticles (N-GQD) were synthesized from a citric acid condensation reaction in the presence of ethylenediamine and subsequently modified by palladium nanoparticles (PdNPs). The electrochemical behavior of AA was investigated, in which the oxidation peak appeared at 0 V related to the AA oxidation. Considering the synergistic effect of Pd nanoparticles as an active electrocatalyst, and N-GQD as an electron transfer accelerator and electrocatalytic activity improving agent, PdNPs@N-GQD hybrid materials showed excellent activity in the direct oxidation of AA. In the optimal conditions, the voltammetric response was linear in the range from 30 to 700 nM and the detection limit was calculated to be 23 nM. The validity and the efficiency of the proposed sensor were successfully tested and confirmed by measuring AA in real samples of chewing tablets, and fruit juice.

Determination of ascorbic acid at solid electrodes modified with L-cysteine

Gold and glassy carbon electrode surfaces were modified with L-cysteine, and the electrochemical behavior of ascorbic acid (AA) was investigated on these new surfaces. To improve the efficiency of electrodes, the electrode surfaces were modified and optimum conditions for AA determination were established. Electrochemical experiments were performed at different potential ranges, the concentration of AA, scan rates, number of polymerization cycles and pH values. Using cyclic voltammetry (CV) technique, optimum conditions were determined as the potential scanning range of 0.2 to 1.5 V vs. Ag/AgCl in 0.1 M phosphate buffer solution (pH 7.02) for the L-cysteine/Au electrode, and -1.95 to 1.9 V vs. Ag/AgCl in 0.1 M phosphate buffer solution (pH 2.7) for the L-cysteine/GC electrode. For the characterization of both modified electrode surfaces, a series of physicochemical techniques was also applied. The usability and selectivity of these two proposed modified electrodes for the determination of AA were investigated using square wave voltammetry (SWV) in the presence of possible interferents, i.e., glycine, L-glutamic acid and uric acid.

Disposable three-dimensional graphene oxide electrode with sandwich-like architecture for the determination of ascorbic acid in fruit juices

This work reports the development of a three-dimensional graphene oxide structure on the screen-printed electrode surface for the detection of ascorbic acid. This electrode was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, RAMAN spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The present work also investigated the electrochemical behavior of ascorbic acid and its electrooxidation mechanism on the three-dimensional graphene oxide surface. The detection of ascorbic acid was conducted by linear scanning voltammetry in the concentration range from 1.0 × 10−5 to 1.0 × 10−2 mol L−1, and the limits of detection and quantification obtained for the proposed electrode were 3.4 × 10−6 and 1.1 × 10−5 mol L−1 (n = 3), respectively. The device also exhibited excellent selectivity, repeatability, reproducibility and stability. The methodology developed was applied for the determination of ascorbic acid in grape and orange juice samples with an accuracy rate ranging from 99% to 105%. These results show that the proposed electrode can be safely and reliably applied for the monitoring of ascorbic acid in fruit juices.

A sensitive and simple electrochemical technique for detecting ascorbic acid content in pharmaceutical and biological compounds

In the current study, a glassy carbon electrode (GCE) modified with graphene-CoS2 nanocomposite was investigated for electrochemical sensing of ascorbic acid. The electrochemical performance of the modified electrode was examined using differential pulse voltammetry (DPV), linear sweep voltammetry (LSV) and chronoamperometry (CHA) techniques. The electrochemical behavior of ascorbic acid at the graphene-CoS2/GCE displayed a higher oxidation current and lower oxidation potential than bare GCE. Under the optimal experimental conditions, the sensor presented a good linear response between the current and the ascorbic acid concentration range of 0.15–245.0 μM, with a low detection limit of 0.05 μM. Finally, the graphene-CoS2 nanocomposite-modified GCE was applied for the determination of ascorbic acid in real samples and displayed excellent recoveries.

Voltammetric Determination of Ascorbic Acid Content in Cabbage Using Anthraquinone Modified Carbon Paste Electrode

In this study, a low-cost, sensitive, and efficient voltammetric method based on anthraquinone modified carbon paste electrode was developed for determination of ascorbic acid in cabbage samples. After cyclic voltammetry was used to investigate the electrochemical behavior of ascorbic acid and to study dependence of oxidative peak current on scan rate and pH, square wave voltammetric method was developed for direct determination of ascorbic acid in cabbage samples. In contrast to the unmodified carbon paste electrode, a remarkable enhancement in oxidative peak current at anthraquinone modified carbon paste electrode confirmed electrocatalytic property of the modifier towards oxidation of ascorbic acid. A better correlation coefficient for the dependence of peak current on the square root of scan rate (R2=0.9963) than on the scan rate (R2=0.9781) indicated that the oxidation of ascorbic acid at anthraquinone modified carbon paste electrode is predominantly governed by diffusion-controlled process. Square wave amplitude, square wave step potential, and square wave frequency are optimized for the investigation of AA in cabbage. The optimized values are 30 mV, 7 mV, and 35 Hz, respectively. Under the optimized method and solution parameters, an excellent linear response was observed between square wave voltammetric peak current of AQMCPE and concentration of ascorbic acid in the range5×10−5to4×10−3 M with a better correlation coefficient (R2=0.9993) and detection limit (LOD=1.84×10−6 M). The ascorbic acid content of the three cabbage samples from three different cabbage growing areas was found in the range3.686±0.026–8.298±0.011 mg/g of powdered cabbage. Excellent recovery results between 95.042 and 96.139% for spiked ascorbic acid in cabbage samples confirmed the potential applicability of the developed method based on AQMCPE for the determination of ascorbic acid in real samples like cabbage.

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.

Voltammetric Determination of Ascorbic Acid in Pharmaceutical Formulations on a Boron Doped Diamond Electrode

The electrochemical behavior of ascorbic acid (AA) is studied by means of cyclic voltammetry (CVA) and square-wave voltammetry (SWVA) on a boron doped diamond electrode (BDD). The possibility of using the voltammetric response signal to determine quantitatively the concentration of AA in an aqueous solution is shown. An analytical direct correlation function for SWVA at BDD is obtained. It is shown that the detection limit for AA is 1.87 μM. The applicability of SWVA for determining the content of AA in pharmaceutical preparations is demonstrated.

Voltammetric Study of Ascorbic Acid Using Polymelamine/Gold Nanoparticle Modified Carbon Paste Electrode

Polymelamine/gold nanoparticle modified carbon paste electrode (PM/AuNPs/CPE) has been developed for voltammetric study of ascorbic acid (AA). The PM/CPE was prepared onto carbon paste electrode surface via electropolymerization, then it has been deposited gold nanoparticle (AuNPs) via electrodeposition for PM/AuNPs/CPE. In pH 7.0 phosphate buffer, PM/AuNPs/CPE was oxidized during the cyclic potential sweep between 0.0 V and 1.5 V, forming polymer and gold nanoparticle at the carbon paste electrode (CPE) surface. The electrochemical behavior of ascorbic acid at the bare CPE, PM/CPE, AuNPs/CPE and PM/AuNPs/CPE were investigated. The oxidation peak potential of ascorbic acid shifts to more negative potential at PM/AuNPs/CPE Moreover, the oxidation peak current significantly increases at PM/AuNPs/CPE. The PM/AuNPs/CPE electrode exhibits a quasi-reversible electron with a peak separation 130 mV. These fenomena indicate that PM/AuNPs/CPE shows highly-efficient catalytic activity to the oxidation of ascorbic acid.

Hydrogen Bond Interaction of Ascorbic Acid with Urea: Experimental and Theoretical Study

Abstract The interactions of ascorbic acid (AA) with urea were investigated by using the cyclic voltammetry, density functional theory, atoms in molecules and natural bond orbital analyses. The experimental and theoretical results show that the hydrogen bonds are formed between AA and urea, wherein the mainly interaction sites are the hydrogen atoms on enediol of AA and the oxygen atom on carbonyl of urea. The electrochemical behavior of AA was significantly affected by above interactions.

Electrochemical determination of ascorbic acid, uric acid and folic acid using carbon paste electrode modified with novel synthesized ferrocene derivative and core–shell magnetic nanoparticles in aqueous media

2‐(4‐Ferrocenyl‐1,2,3‐triazol‐1‐yl)‐1‐(naphthalen‐2‐yl)ethanone (2FTNE) and magnetic core–shell manganese ferrite nanoparticles (CMNP) were fabricated and applied to produce a modified carbon paste electrode (CPE). The electrochemical behaviour of ascorbic acid (AA) was investigated using cyclic voltammetry and measured by square wave voltammetry along with that of uric acid (UA) and folic acid (FA). The 2FTNECMNP‐modified CPE (2FTNECMNPPE) had electrocatalytic activity towards AA oxidation that was greater than that of bare CPE and CMNP‐modified CPE. Based on the results, the linear oxidation peak current was 0.01–60 μM for AA level and the correlation coefficient was 0.9997. According to three times the standard deviation for the blank, the limit of detection was calculated as 0.002 μM. Our results showed an increase in selectivity, stability and reproducibility for 2FTNECMNPPE, which significantly could measure AA, UA and FA levels in AA ampoule, FA tablet and urine samples. It can be concluded that 2FTNECMNPPE has promising capacity in the development of electrochemical sensors.

Facile green synthesis of reduced graphene oxide/tin oxide composite for highly selective and ultra-sensitive detection of ascorbic acid

In this work, we report a novel, cost effective and environmental-friendly green synthesis method of reduced graphene oxide (rGO) – tin oxide (SnO2) composite using lemon extract by hydrothermal process for selective and ultra-sensitive electrochemical detection of ascorbic acid. The electrochemical behavior of ascorbic acid at the surface of rGO-SnO2 composite modified glassy carbon electrode (GCE) was investigated by cyclic voltammetry (CV) technique whilst ascorbic acid sensing was performed by using differential pulse voltammetry (DPV) technique. An excellent sensitivity of 1200 μA mM−1 cm−2 (R2 = 0.990) towards ascorbic acid in the wide dynamic range of 400 μM −1600 μM without any surface fouling effect was observed which is, to the best of our knowledge, ~1.6 folds higher than previously reported ascorbic acid sensors. The as-fabricated sensor exhibited lower limit of detection (38.7 μM), superior reproducibility and selectivity towards interfering species such as glucose, urea, uric acid and Na+ ions. This enhanced sensing ability was studied and discussed in terms of forward biased nano-Schottky barriers at the rGO-SnO2 interface. The sensor was successfully evaluated for the detection of ascorbic acid in the vitamin C tablets and to predict unknown concentrations of ascorbic acid in PBS solution. This ultrasensitive, binder free rGO–SnO2 composite based sensor can be used for a simple, low cost and voltammetric detection of ascorbic acid in clinical diagnostics, pharmaceutical and food industries.

Novel insights into the effect of folate–albumin binding on the transport of ascorbic acid as an anticancer agent: chemometric analysis based on combined spectroscopic and electrochemical studies

The electrochemical behavior of ascorbic acid and folic acid upon their interaction with albumin is investigated using electrochemical, chemometric and docking studies.

Interactions between Vitamin C and Nanocolloidal Silver Particles Studied by Cyclic Voltammetry and UV‐Vis Spectrophotometry

AbstractThe effect of silver nanoparticles on human health has been investigated and the controversial opinions about their use in a wide variety of commercial products were expressed. Their interactions with vitamins and salts constitute an important step to elucidate the possible improper transformations knowing that the silver nanoparticles could have the effect on cell viability. In this circumstance, in our study we investigated the electrochemical behavior of ascorbic acid, in NaCl blank solution and NaCl solution containing the silver nanoparticles using the cyclic voltammetry and current constant electrolysis associated to UV‐Vis spectrophotommetry. The presence of silver nanoparticles (nAg) leads to a more rapid electrodegradation of vitamin C (VitC) in solution of NaCl, the zero‐order reaction kinetics being followed. The rate constant value of 0.78 u.A. min−1 was obtained compared to the value of 0.39 u.A. min−1 that was computed in the absence of nAg. The Vitamin C degradation mechanism was also proposed.

Electropolymerization of a conductive β-cyclodextrin polymer on reduced graphene oxide modified screen-printed electrode for simultaneous determination of ascorbic acid, dopamine and uric acid

This work introduces an electrochemical sensor fabricated by electropolymerization of a conductive β-cyclodextrin (β-CD) polymer onto a reduced graphene oxide (rGO)-decorated screen-printed electrode (SPE). The coated β-CD polymer had a high supramolecular recognition capability and superior electrical conductivity, which can improve the electrochemical properties of the β-CD/rGO/SPE electrode. Electrochemical behaviors of ascorbic acid (AA), dopamine (DA), and uric acid (UA) on the β-CD/rGO/SPE electrode were investigated by cyclic voltammetry and differential pulse voltammetry. The anodic peaks of these three molecules were separated perfectly at the sensor, indicating that the β-CD/rGO/SPE electrode can simultaneously detect these three molecules. The linear ranges for AA, DA and UA were 0.2–2mM, 0.05–50μM and 0.08–150μM, respectively. The corresponding detection limits were 0.067mM, 0.017μM and 0.026μM, respectively. As a practical application, the proposed sensor was successfully applied to quantify the concentrations of AA, DA and UA in real biological samples. These results demonstrate that this β-CD/rGO/SPE electrode can be a promising electrochemical sensor for electrocatalytic applications.

Electrodeposited reduced graphene oxide incorporating polymerization of l-lysine on electrode surface and its application in simultaneous electrochemical determination of ascorbic acid, dopamine and uric acid

This paper demonstrates a novel strategy for the construction of a graphene hybrid composites film, which was fabricated by electrodeposited reduced graphene oxide (ERGO) incorporating polymerization of l-lysine (PLL) onto glassy carbon electrode (GCE). Here we show that graphene films can be prepared on electrodes directly from GO dispersions by one-step electrodeposition technique based on electropolymerized PLL as a positively charged polymer interface to adsorb negatively charged GO nanosheets through electrostatic attraction. The thickness of graphene film can be easily controlled by using the electrodeposition technique, a distinct advantage over previously developed methods. The electrochemically reduced process of GO and electropolymerization of l-lysine were investigated by cyclic voltammetry with a wide potential range. The surface morphology of the modified electrode was characterized by scanning electron microscopy. The ERGO/PLL/GCE shows conducive to electron transfer kinetics for Fe(CN)63−/Fe(CN)64− redox probes, compared with bare GCE, PLL/GCE and ERGO/GCE. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) at ERGO/PLL/GCE were investigated by cyclic voltammetry, and the results suggest that the modified electrode exhibits enhanced electrocatalytic activity toward these important molecules. Under physiological condition and in the co-existence system of AA, DA and UA, the ERGO/PLL/GCE showed linear voltammetric responses in the concentration of 100μM–1200μM for AA, 2.0μM–60μM for DA and 20μM–200μM for UA, and with the detection limits (S/N=3) of 2.0μM, 0.10μM and 0.15μM for AA, DA and UA, respectively. The developed method has been applied to simultaneous determination of AA, DA and UA in human urine with satisfactory recoveries of 104.2%, 95.4% and 99.9%, respectively. This work demonstrates that the attractive features of ERGO/PLL provide promising applications in simultaneous determination of AA, DA and UA in physiological and pathological studies.

Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid.

Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA.

聚乙烯亚胺功能化石墨烯修饰电极同时测定抗坏血酸、多巴胺、尿酸和色氨酸

制备了聚乙烯亚胺(PEI)功能化的石墨烯(G)修饰电极以实现抗坏血酸(AA)、 多巴胺(DA)、 尿酸(UA)和色氨酸(Trp)的分离及同时测定. 采用红外光谱(FTIR)、 紫外-可见吸收光谱(UV-Vis)、 X射线粉末衍射仪(XRD)和透射电子显微镜(TEM)对电极修饰材料进行了表征, 并优化了该修饰电极同时测定AA, DA, UA和Trp的实验条件. 在聚乙烯亚胺功能化石墨烯修饰的玻碳电极(PEI-G/GCE)上实现了AA, DA, UA 和Trp氧化峰的分离, AA-DA, DA-UA和UA-Trp的氧化峰电位差分别为298, 130和350 mV. 该修饰电极对AA, DA, UA和Trp的检测线性范围分别为50~5800, 30~2570, 0.05~400和6~1000 μmol/L; 检出限分别为16.67, 10, 0.017和2 μmol/L.

Novel functionalized multiwalled carbon nanotube-glassy carbon electrode for simultaneous determination of ascorbic acid and uric acid

In this study the electrochemical behavior of ascorbic acid (AA) and uric acid (UA) at the surface of glassy carbon electrodes (GCEs) modified by multi-walled carbon nanotubes (MWCNTs) functionalized with Fe3+ complex was investigated. The voltammetric studies using the modified electrode showed two well-resolved anodic peaks for AA and UA with a potential difference of ∼0.4V, revealing the possibility of the simultaneous electrochemical detection of these compounds. First, the electrochemical behavior of ferric/ferrous at Fe3+complex/MWNTs/nafion (FeCMN) modified electrode was studied. The results showed an adsorption-controlled reaction at the modified electrode. Then, the behavior of ascorbic acid and uric acid at the modified electrode was investigated. The optimum analytical conditions were sought. Linear calibration plots were obtained over the range of 4.0 to 600μmoll−1 and 0.3 to 490μmoll−1 with detection limits (3σ) of 2.57μmoll−1 and 0.137μmoll−1 for AA and UA, respectively.The electrode with the best conditions was applied for selective determination of AA and UA in biological matrices.

Screen Printed Carbon Nano-Powder for Ascorbic Acid Determination with Differential Pulse Voltammetry

Carbon nanopowder mixed with carbon ink was used as a working screen-printed electrode. This electrode consists of carbon nanopowder working electrode, carbon counter electrode, and silver/silver chloride reference electrode. The electrochemical behavior of ascorbic acid has been studied by cyclic voltammetry and differential pulse voltammetry with screen-printed carbon nanopowder electrode. The propose electrode will enhanced the sensitivity for antioxidance determination because increasing of the surface area of the working electrode. The voltammetric sensor offers several advantages to both the green chemistry and eco-friendly. The method was successfully employed with 2 microliter of the working solution dropped on the electrode surface. A linear concentration, limit of quantitation and limit of detection was sufficient for the ascorbic acid determination in the vitamin C tablet. The results obtained for the sample juices demonstrated that the powerful of the method.

Electrochemical studies of ascorbic acid, dopamine, and uric acid at adl-norvaline-deposited glassy carbon electrode

The electrochemical behavior of ascorbic acid (AA), dopamine (DA), and uric acid (UA) on a dl-norvaline-modified glassy carbon electrode (GCE) was studied by cyclic voltammetry. The bare GCE failed to distinguish the oxidation peaks of AA, DA, and UA in phosphate-buffered solution (pH 5.0), while the dl-norvaline-modified GCE could separate them efficiently. In differential pulse voltammetric (DPV) measurements, the modified electrode resolved the overlapped voltammetric responses of AA, DA, and UA into three well-defined voltammetric peaks. Under optimum conditions, the anodic peak currents of DPV for AA, DA, and UA were proportional to the concentration in the range of 20–400, 1–40, and 15–180 μmol/L, respectively, with a correlation coefficient (r) of around 0.998. The detection limits were 5, 0.3, and 10 μmol/L (S/N = 3) for AA, DA, and UA, respectively. Satisfactory results were achieved for the determination of AA in vitamin C tablets, DA in a dopamine ampoule sample, and UA in human blood serum samples.