Amperometric Detection Of Ascorbic Acid Research Articles

A Comparison of the Sensing Behavior for Pt-Mo/C-, Pt-Zr/C-, Pt-Fe-Ir/C-, and Pt/C-Modified Glassy Carbon Electrodes for the Oxidation of Ascorbic Acid and Dopamine

This study compares the sensing performance for platinum-molybdenum-, platinum-zirconium-, platinum-iron-iridium-, and platinum-modified electrodes in terms of the amperometric detection of ascorbic acid (AA) and dopamine (DA). The Pt, Pt-Mo, Pt-Zr, and Pt-Fe-Ir electrocatalysts are fabricated by chemical reduction on a carbon black support (XC-72) and are further modified on a glassy carbon electrode (GCE) as sensing electrodes. The Pt-Mo/C/GCE exhibits better electrocatalytic activity toward AA and DA than the Pt/C/GCE, Pt-Zr/C/GCE, and Pt-Fe-Ir/C/GCE. The Pt-Mo/C/GCE exhibits a sensitivity of 31.29 µA mM−1 to AA at 0.3 V vs. Ag/AgCl and a sensitivity of 72.24 µA mM−1 to DA at 0.6 V vs. Ag/AgCl and is reproducible and stable. This electrode has a respective limit of detection of 7.69 and 6.14 µM for AA and DA. Sucrose, citric acid, tartaric acid, and uric acid do not interfere with AA and DA detection. The diffusion coefficient and kinetic parameters, such as the catalytic rate constant and the heterogeneous rate constant for AA and DA, are determined using electrochemical approaches.

An Ascorbate Bluetooth© Analyzer for Quality Control of Fresh-Cut Parsley Supply Chain.

This work provides companies in the fresh-cut produce sector with an Ascorbate Bluetooth© Analyzer (ABA), a screen-printed sensor-based device for ascorbic acid (AA) detection, for quality control all along the supply chain. The amperometric detection of AA on fresh and fresh-cut parsley, under correct and incorrect storage temperature, allowed us to investigate the kinetics of AA decay in response to oxidative stress. The role of ascorbate oxidase (AOx) and ascorbate peroxidase (APx) was studied. ABA was used in situ by unskilled personnel. Treatments influenced AA decay kinetics, which were linear in fresh parsley, and non-linear in fresh-cut. Two hours at 28 °C immediately after chopping, the resilience of the fresh-cut parsley was reduced, even though the cold chain was restored. Two hours at −2 °C caused a rapid loss of AA until its complete decay after 72 h. Significant differences between treatments were observed in both the expression and activity of AOx and APx. ABA registered sudden changes of parsley AA following unpredicted variations of temperature during processing or transport. It was useful to remedy the effects of unexpected flaws in the cold chain, which can be proposed for quality preservation of different fresh-cut produce.

A Novel Design and Fabrication of Ascorbic Acid Sensitive Biosensor Based on Combination of HAP/rGO/AuNPs Composite and Ascorbate Oxidase

In this study, a new HAP/rGO/AuNPs-AO modified carbon electrode (GCE) was fabricated for amperometric detection of ascorbic acid. The HAP/rGO/AuNPs composite was prepared by one-step hydrothermal method. The large specific surface area, strong adsorption and excellent biocompatibility of HAP nanowires enabled fast, stable and accurate detection of ascorbic acid. As array of quantum dot, AuNPs had strong electrocatalytic activity in addition to good adsorption to enzymes, which could provide high sensitivity and low limit of detection for biosensor. Then rGO ensured that current signal could be quickly transferred from the composite to electrode. Under the optimum conditions, the prepared biosensor demonstrated a wide linear range from 0.39 to 36 mM (R2 = 0.99845), a low limit of detection (3.39 μM, S/N = 3) and a high sensitivity (15.949 mA moL−1) with good selectivity, stability (10.8%) and repeatability (3.9%), which might providing a reasonable and reliable way for ascorbic acid detection.

Quaternary phosphonium-based (TPQPCl)-ionomer/graphite nanoplatelets composite chemically modified electrodes: a novel platform for sensing applications

Ionomer (TPQPCl)/graphite nanoplatelet-coated electrodes are developed as a new sensing platform for amperometric detection of ascorbic acid.

Electrocatalytic performance of cobalt microparticles film-modified platinum disk electrode for amperometric detection of ascorbic acid

Deposited cobalt microparticales (Co-MPs) film onto the platinum disk electrode has been successfully used as a new amperometric sensor for the determination of ascorbic acid (AA). AA is detected by surface catalyzed oxidation involving cobalt(III) oxyhydroxides in alkaline solution. The Co-MPs/Pt electrode exhibits a high electrocatalytic activity toward the AA oxidation. The diffusion coefficient of AA (6.09 × 105 cm2/s) and the catalytic rate constant (k cat = 6.27 × 103 M–1s–1) have been determined using electrochemical approaches. The amperometric response of the modified electrode is linear against the AA concentration in the range (0.01‒0.48 mM). The sensor displays the best activity with a high response signal, a good sensitivity of 74.3 μA/mM, a low detection limit of 2.5 μM (signal/noise = 3) and a fast response time (<3 s). Moreover, the reproducibility, selectivity and applicability of this biosensor are satisfactorily evaluated.

Characterization protocol to improve the electroanalytical response of graphene–polymer nanocomposite sensors

This work is focused on the application of advanced characterization techniques for the development of optimized electrochemical sensors based on graphene–polymer nanocomposites. Reduced graphene oxide (rGO) was synthesized and used as conducting nanofiller material in nanocomposite electrodes based on epoxy resin. A series of rGO/epoxy nanocomposite electrodes were fabricated containing 8%–20% of nanofiller material. Composition ratios have been studied using percolation theory and characterized by different electrochemical techniques, demonstrating that an optimization of the rGO/epoxy composition ratio is mandatory to enhance electrochemical performance. The potential of this approach in terms of electroanalytical response has been demonstrated by means of the amperometric detection of ascorbic acid, which was used as a model analyte. Finally, different morphological experiments were also carried out in order to verify the electrochemical and electroanalytical enhancement obtained for the optimized-nanocomposite sensors.

High-sensitivity ascorbic acid sensor using graphene sheet/graphene nanoribbon hybrid material as an enhanced electrochemical sensing platform

A novel electrode material of graphene sheet/graphene nanoribbon (GS/GNR) hybrid material was developed by incorporating graphene nanoribbons into graphene nanosheets through simultaneous chemical reduction of graphene oxide sheets and graphene oxide ribbons. The structure and properties of synthesized GS/GNR were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, Brunauer Emmett Teller measurements and Fourier transform infrared spectroscopy. This work compares the electro catalytic performance of the GS/GNR, chemically reduced graphene oxide sheets (CRGOS) and GS/carbon nanotube (CNT) by modifying the glassy carbon electrode (GCE) using ascorbic acid (AA) as analyte. The electrochemical impedance spectroscopy revealed that the charge transfer resistance of GS/GNR modified electrode was less than that of CRGOS modified electrode and bare GCE. The cyclic voltammetric sensing of GS/GNR modified electrode towards AA was negatively shifted (0.08V) compared to CRGOS, GS/CNT modified electrode and bare GCE (0.222, 0.150 and 0.666V). This catalytic oxidation allows an amperometric detection of AA with a detection limit of 230nM and sensitivity of 22nAμM−1cm−2. GS/GNR modified GCE exhibited a high selectivity for ascorbic acid in the presence of other interferents like dopamine, uric acid and citric acid.

Amperometric Determination of Ascorbic Acid on an Au Electrode Modified by a Composite Film of Poly(3,4-ethylenedioxythiophene) and Superconductive Carbon Black.

A new composite film-modified electrode was prepared by the electropolymerisation of poly(3,4-ethylenedioxythiophene) (PEDOT) and superconductive carbon black (SCB) on a gold electrode. The PEDOT-SCB/Au electrode exhibited excellent ability towards the electrocatalytic oxidation of ascorbic acid, in terms of a 480 mV shift of the oxidation potential in the negative direction, and a dramatically enhanced oxidation current. Under the optimum conditions, the amperometric detection of ascorbic acid provided a wide linear detection range from 1.0 × 10(-7) to 8.0 × 10(-4) M, and a detection limit of 5.0 × 10(-8) M (S/N = 2) as well as good reproducibility and stability.

Nonenzymatic amperometric sensor for ascorbic acid based on hollow gold/ruthenium nanoshells

We report a new nonenzymatic amperometric detection of ascorbic acid (AA) using a glassy carbon (GC) disk electrode modified with hollow gold/ruthenium (hAu–Ru) nanoshells, which exhibited decent sensing characteristics. The hAu–Ru nanoshells were prepared by the incorporation of Ru on hollow gold (hAu) nanoshells from Co nanoparticle templates, which enabled AA selectivity against glucose without aid of enzyme or membrane. The structure and electrocatalytic activities of the hAu–Ru catalysts were characterized by spectroscopic and electrochemical techniques. The hAu–Ru loaded on GC electrode (hAu–Ru/GC) showed sensitivity of 426μAmM−1cm−2 (normalized to the GC disk area) for the linear dynamic range of <5μM to 2mM AA at physiological pH. The response time and detection limit were 1.6s and 2.2μM, respectively. Furthermore, the hAu–Ru/GC electrode displayed remarkable selectivity for ascorbic acid over all potential biological interferents, including glucose, uric acid (UA), dopamine (DA), 4-acetamidophenol (AP), and nicotinamide adenine dinucleotide (NADH), which could be especially good for biological sensing.

Microfluidic thin-layer flow cell for conducting polymer growth and electroanalysis

The design and fabrication of a low cost and versatile poly(dimethylsiloxane) (PDMS)-glass microchip configured to house an electrochemical thin-layer flow cell is reported. The microchip contains an integrated electrochemical cell comprising a sputtered channel gold working electrode (110μmx5mm) and a reference and auxiliary electrode housed together in the channel outlet. The facile fabrication method allows for the production of fully disposable, gasket-free thin-layer cells for a range of channel depths (35–180μm), that are suitable for low-cost, chip-based electroanalytical applications. The microchip was found to exhibit thin-layer behaviour during a series of voltammetric experiments conducted in ferrocyanide/ferricyanide. The cell was observed to experience a high resistance to current, which was dependent on the distance from the channel working electrode to the auxiliary electrode.Polyaniline (PANI) monoliths were grown electrochemically onto the channel electrode (5mm in length). The thickness of these monoliths was shown to be uniform along the length of the electrode. This demonstrates that the IR drop along the channel was not significant over this electrode length. The growth behaviour of the PANI on-chip was further examined in terms of channel depth and flow rate. It was observed that, under certain flow conditions, PANI monolith thicknesses were limited to approximately half the channel depth being employed. This was attributed to increasing volumetric flow rates during PANI growth. Increasing flow and hence convection rates were due to the displacing of channel volume during voltammetric electropolymerisation of PANI.The microfluidic electrochemical cell incorporating the PANI-modified channel electrode was then used for the amperometric detection of ascorbic acid. When the working channel electrode was placed closest to the channel outlet, the microchip was capable of the detection of ascorbic acid at a sensitivity of 15.7μAmM−1cm−1 which is greater than reported previously under similar conditions.

Strategies for the optimization of carbon nanotube/polymer ratio in composite materials: Applications as voltammetric sensors

Multiwall carbon nanotubes and resin epoxy have been used to fabricate a composite electrode for electroanalytical purposes. The optimum composite proportions for high electrode sensitivity, low limit of detection and fast response were investigated. Compositions were characterized by percolation theory, electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, atomic force microscopy and chronoamperometry. We found that around the optimum composite proportion, the electrode performance is less affected by small variations in the composition of the composite. These composite electrodes provide easy surface renewal, low background current, an efficient mass transport and are suitable for chemical modification. The potentiality of this approach in terms of electroanalytical response is demonstrated by means of the amperometric detection of ascorbic acid in water solution.

Electrooxidation and Amperometric Detection of Ascorbic Acid at GC Electrode Modified by Electropolymerization of N,N‐Dimethylaniline

AbstractThe polymer film of N,N‐dimethylaniline (DMA) is deposited on the electrochemically pretreated glassy carbon (GC) electrode by continuous electrooxidation of the monomer. This poly N,N‐dimethylaniline (PDMA) film‐coated electrode can be used as an amperometric sensor of ascorbic acid (AA). The polymer film (thickness (ϕ): 0.3±0.02 μm) having positive charge in its backbone attracts the anionic species AA. Thus, the anodic peak potential (350 mV vs. Ag|AgCl|NaCl(sat)) for the oxidation of AA at the bare electrode is largely shifted to the negative value (150 mV) at this electrode. The PDMA film‐coated electrode is stable in acidic, alkaline and neutral media and can sense AA at different pH's. The diffusion coefficients of AA in solution (D) and in film (Ds) were estimated by rotating disk electrode voltammetry: D=(5.5±0.1)×10−6 cm2 s−1 and Ds=(6.3±0.2)×10−8, (6.0±0.2)×10−8 and (4.7±0.2)×10−8 cm2 s−1 for 0.5, 1.5 and 3.0 mM AA, respectively. A permeability of AA through the PDMA film was found to decrease with increasing the concentration of AA in the solution. In the chronoamperometry, the current response for the oxidation of AA at different times elapsed after potential‐step application is linearly increased with the increase in AA concentration in a wide range of its concentration from 25 μM to 1.65 mM. In the hydrodynamic amperometry, a successive addition of 10 μM AA caused the successive increase in current response with equal amplitude and the sensitivity was calculated as 0.178 μA cm−2 μM−1. So, the fouling of the electrode surface caused by the oxidized product of AA is markedly eliminated at this PDMA film‐coated electrode. A flow injection analysis based on the present electrode was performed to estimate the concentration of vitamin C in fruit juice.