A differential pulse voltammetric method for simultaneous determination of ascorbic acid,dopamine, and uric acid using poly (3-(5-chloro-2-hydroxyphenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid) film modified glassy carbon electrode

A stable modified glassy carbon electrode based on the poly 3-(5-chloro-2-hydroxyphenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid (CDDA) film was prepared by electrochemical polymerization technique to investigate its electrochemical behavior by cyclic voltammetry. The properties of the electrodeposited films, during preparation under different conditions, and their stability were examined. The homogeneous rate constant, k_s, for the electron transfer between CDDA and glassy carbon electrode was calculated as 5.25(±0.20) × 10² cm s⁻¹. The modified electrode showed electrocatalytic activity toward ascorbic acid (AA), dopamine (DA), and uric acid (UA) oxidation in a buffer solution (pH 4.0) with a diminution of their overpotential of about 0.12, 0.35, and 0.50 V for AA, DA, and UA, respectively. An increase could also be observed in their peak currents. The modified glassy carbon electrode was applied to the electrocatalytic oxidation of DA, AA, and UA, which resolved the overlapping of the anodic peaks of DA, AA, and UA into three well-defined voltammetric peaks in differential pulse voltammetry (DPV). This modified electrode was quite effective not only for detecting DA, AA, and UA, but also for simultaneous determination of these species in a mixture. The separation of the oxidation peak potentials for ascorbic acid–dopamine and dopamine–uric acid were about 0.16 V and 0.17 V, respectively. The final DPV peaks potential of AA, DA and UA were 0.28, 0.44, and 0.61 V, respectively. The calibration curves for DA, AA, and UA were linear for a wide range of concentrations of each species including 5.0–240 μmol L⁻¹ AA, 5.0–280 μmol L⁻¹ DA, and 0.1–18.0 μmol L⁻¹ UA. Detection limits of 1.43 μmol L⁻¹ AA, 0.29 μmol L⁻¹ DA and 0.016 μmol L⁻¹ UA were observed at pH 4. Interference studies showed that the modified electrode exhibits excellent selectivity toward AA, DA, and UA.     

The role of bromine adlayer at palladium electrode in the electrochemical oxidation of dopamine in alkaline solution

A palladium electrode modified with bromine monolayer was fabricated throughout a spontaneous oxidative chemisorption of bromide ions contained in an alkaline solution. The surface coverage and the apparent double layer capacitance induced by the adsorption of bromide ions under the present applied potential indicates the formation of incomplete monolayer due to a prominent co-adsorption of hydroxyl ions (OH⁻). The film modified electrode exhibited a substantial reactivity and high sensitivity in the electrochemical oxidation of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA). This trend was attributed to the structure and the composition of the bromine adlayer which renders a partial negative charge capable of attracting selectively the cationic DA and repelling anionic AA and UA. The peak currents of DA in the binary and ternary mixtures were well-separated, well-defined and increased linearly with respect to its concentration. The interference property expected by the presence of both AA and UA has been advantageously eliminated at the bromine-adlayer modified electrode. The apparent diffusion coefficient value of DA was 1.37 × 10⁻⁸ m² s⁻¹, based on an amperometric current–time study. The present system provides a simple and fundamental approach for the simultaneous and selective determination of DA in the presence of AA and UA.     

Silver nanoparticles modified carbon nanotube paste electrode for simultaneous determination of dopamine and ascorbic acid

A novel modified carbon-paste electrode was employed for the simultaneous determination of dopamine (DA) and ascorbic acid (AA) with good selectivity and high sensitivity. Silver nanoparticle and carbon nanotube modified carbon-paste electrode (Ag/CNT–CPE) displayed excellent electrochemical catalytic activities towards dopamine (DA) and ascorbic acid (AA). The oxidation overpotentials of DA and AA were decreased significantly compared with those obtained at the bare CPE. Differential pulse voltammetry was used for the simultaneous determination of DA and AA. The peak separation between DA and AA was 67 mV. The calibration curves for DA and AA were obtained in the range of 8.0 × 10⁻⁷–6.4 × 10⁻⁵ M and 3.0 × 10⁻⁵–2.0 × 10⁻³ M, respectively. The lowest detection limits (S/N = 3) were 3.0 × 10⁻⁷ M and 1.2 × 10⁻⁵ M for DA and AA, respectively. Method was applied to the determination of DA and AA in real samples.     

Amperometric determination of hydrogen peroxide on surface of a novel PbPCNF-modified carbon-ceramic electrode in acidic medium

This work describes the electrochemical behavior of lead pentacyanonitrosylferrate (PbPCNF) film immobilized on the surface of carbon-ceramic electrode (CCE) and its electrocatalytic activity toward the reduction of hydrogen peroxide in acidic medium. The electrode was prepared by electroless derivatization of Pb-doped carbon-ceramic electrode surface to the redox active PbPCNF solid film, in the presence of sodium pentacyanonitrosylferrate, Na₂[Fe(CN)₅NO], (PCNF). The morphology and the composition of the PbPCNF-modified CCE were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and Fourier transform infrared (FTIR) techniques. Various experimental parameters influencing the electrochemical behavior of the modified electrode were optimized by varying the supporting electrolyte, potential scan rates and solution pH. The modified electrode showed an excellent electrocatalytic behavior toward the reduction of hydrogen peroxide in 0.5 M KNO₃ at pH 4. The sensor exhibited a good linear response for H₂O₂ concentration over the range 0.5–58.75 μM with a detection limit of 0.4 μM (S/N = 3). The interferences of dopamine (DA), uric acid (UA), and ascorbic acid (AA) were negligible in the determination of H₂O₂. The proposed sensor showed good stability, reproducibility and outstanding for long-term use.     

Selective determination of dopamine in the presence of ascorbic acid at a multi-wall carbon nanotube-poly(3,5-dihydroxy benzoic acid) film modified electrode

A sensitive and selective method for determination of dopamine (DA) using multi-wall carbon nanotube (MWCNT)-poly(3,5-dihydroxy benzoic acid) [poly(DBA)] modified electrode is developed. The modified electrode shows excellent electrocatalytic activity toward the oxidation of dopamine in phosphate buffer solutions at pH 7.4. Using cyclic voltammetry, the linear range of 1 × 10⁻⁷–7.0 × 10⁻⁵ M in the interference of 500 μM ascorbic acid (AA) and the detection limit of 1.0 × 10⁻⁸ M were estimated for the measurement of DA in pH 7.4 phosphate buffer solutions. The value of DA current retained 98.36% of the initial response current after the modified electrode exposed to the air for one week. The interference studies showed that the modified electrode excludes effectively large excess of AA. The kinetic characteristics of the transfer of DA demonstrated that the electron propagation between DA and electrode was accelerated at MWCNT-poly(DBA) modified electrode. The work provided a valid and simple approach to selectively detect dopamine in the presence of AA in physiological environment.     

Graphite oxide bulk modified carbon paste electrode for the selective detection of dopamine: A voltammetric study

A novel electrochemical sensor for the selective and sensitive detection of dopamine (DA) in presence of large excess of ascorbic acid (AA) and uric acid (UA) at physiological pH was developed by the bulk modification of carbon paste electrode (CPE) with biocompatible graphite oxide (GO). Very small quantity of GO in carbon paste matrix imparted selectivity through electrostatic interactions. The modifier was characterized using infrared spectroscopy and powder X-ray diffraction. Large peak separation, good sensitivity and stability allow this modified electrode to analyze DA individually and simultaneously along with AA and UA. Applying differential pulse technique, DA could be detected even in the presence of 1000 fold excess of AA and UA. A linear dynamic range of 0.07–70 μM with detection limit of 1.5 × 10⁻⁸ M was obtained for DA. None of the bulk modified electrodes reported in the literature have shown such a low detection limit at the physiological pH. The practical application of the modified electrode was demonstrated by spiking the human blood serum and cerebral fluid with dopamine and the results obtained were satisfactory.     

Simultaneous determination of epinephrine and uric acid at a gold electrode modified by a 2-(2,3-dihydroxy phenyl)-1, 3-dithiane self-assembled monolayer

In the present paper, the use of a gold electrode modified by 2-(2,3-dihydroxy phenyl)-1,3-dithiane self-assembled monolayer (DPDSAM) for the determination of epinephrine (EP) and uric acid (UA) was described. Initially, cyclic voltammetry was used to investigate the redox properties of this modified electrode at various scan rates. The apparent charge transfer rate constant, k_s, and transfer coefficient, α, were calculated. Next, the mediated oxidation of EP at the modified electrode was described. At the optimum pH of 8.0, the oxidation of EP occurs at a potential about 155 mV less positive than that of an unmodified gold electrode. The values of electron transfer coefficients (α = 0.356), catalytic rate constant (k = 1.624 × 10⁴ M⁻¹ s⁻¹) and diffusion coefficient (D = 1.04 × 10⁻⁶ cm² s⁻¹) were calculated for EP, using electrochemical approaches. Based on differential pulse voltammetry, the oxidation of EP exhibited a dynamic range between 0.7 and 500.0 μM and a detection limit (3σ) of 0.51 μM. Furthermore, simultaneous determination of EP and UA at the modified electrode was described. Finally, this method was used for the determination of EP in EP ampoule.     

Simultaneous electrochemical detection of uric acid and ascorbic acid at a poly(N,N-dimethylaniline) film-coated GC electrode

A polymer film of N,N-dimethylaniline (PDMA) having a positive charge on the quarternary ammonium group in its backbone was electrochemically deposited on a glassy carbon (GC) electrode surface. The resulting film-coated GC electrode was used to detect uric acid (UA) electrochemically in the presence of ascorbic acid (AA). Both UA and AA are anionic in a solution of pH 7 and thus were attracted to the film, which lowered their oxidation potentials and increased their oxidation currents. In cyclic voltammetric measurements, the negative shift of the oxidation potential of UA (by 0.28 V) compared with that at the bare electrode was larger than that of AA (by 0.2 V). Also the increase in the oxidation current of UA at the PDMA film-coated electrode was larger than that of AA. In square wave voltammetric measurements, the PDMA film-coated electrode could separate the oxidation peak potentials of UA and AA present in the same solution by about 200 mV though the bare electrode gave a single broad response. A successful elimination of the fouling effect by the oxidized product of AA on the response of UA has been achieved at the PDMA film-coated electrode. The detection limit of UA in the presence of 160-fold excess of AA was found as 1.25 μM and the current response for UA increased linearly with increase of its concentration from 1.25 to 68.75 μM in the presence of AA with a correlation coefficient of 0.999 and a sensitivity of 0.0276 μA μM⁻¹. In flow injection analysis, a good linear relationship between the oxidation current and the concentration from 2 to 21 μM of UA was found. The sensitivity of the PDMA film-coated electrode towards UA was calculated as 0.0285 μA μM⁻¹ with a correlation coefficient of 0.997. The stable and reproducible response for both AA and UA at the PDMA film-coated electrode was verified by flow injection experiments. As the response of UA was reproducible in the presence of AA, it was expected that the oxidized product of AA would not affect the electrode response of UA. Moreover, the physiologically common interferents (i.e., glucose, purine, urea and citrate) negligibly affected the response of UA. The PDMA film-coated electrode exhibited a stable and sensitive response to UA in the presence of interferents.     

Electrochemical analysis of ascorbic acid using copper nanoparticles/polyaniline modified glassy carbon electrode

The electrosynthesis of polyaniline (PANI) film has been achieved on glassy carbon electrode (GCE) in a novel ionic liquid medium by means of cyclic voltammetry (CV). Then a copper nanoparticles (Cu-NPs) film was in situ electrochemically deposited on the surface of PANI/GCE. Electrochemical behavior and surface characteristics of the Cu-NPs/PANI/GCE were studied using cyclic voltammetry, scanning electron microscopy (SEM) and the results confirmed the presence of PANI and Cu-NPs on the electrode surface. Cu-NPs were highly dispersed and firmly stabilized by surface attachment of the PANI, which was prepared in ionic liquid and strongly attached to the electrode surface. The Cu-NPs/PANI/GCE showed excellent electrocatalytic activity toward the oxidation of ascorbic acid (AA) under weakly basic conditions. Amperometry was carried out to determine the concentration of AA at 0.2 V, and a good linear concentration range from 0.005 to 3.5 mM was found. The Cu-NPs/PANI composite film on GCE surface showed good reproducibility and stability.     

Simultaneous determination of adenine and guanine utilizing PbO2-carbon nanotubes-ionic liquid composite film modified glassy carbon electrode

A novel and reliable electrochemical sensor based on PbO₂-carbon nanotubes-room temperature ionic liquid (i.e., 1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6) composite film modified glassy carbon electrode (GCE) (PbO₂–MWNT–RTIL/GCE) was proposed for simultaneous and individual determination of guanine and adenine. The guanine and adenine oxidation responses were monitored by differential pulse voltammetric (DPV) measurement. Compared with the bare electrode, the PbO₂–MWNT–RTIL/GCE not only significantly enhanced the oxidation peak currents of guanine and adenine, but also lowered their oxidation overpotentials, suggesting that the synergistic effect of PbO₂, MWNT and RTIL could dramatically improve the determining sensitivity of guanine and adenine. The PbO₂–MWNT–RTIL/GCE showed good stability, high accumulation efficiency and enhanced electrocatalytic ability for the detection of guanine and adenine. Besides, the modified electrode also exhibited good behaviors in the simultaneous detection of adenine and guanine with the peak separation of 0.29 V in 0.1 M pH 7.0 phosphate buffer solution (PBS). Under the optimal conditions, the detection limit for individual determination of guanine and adenine was 6.0 × 10⁻⁹ M and 3.0 × 10⁻⁸ M (S/N = 3), respectively. The proposed method for the measurements of guanine and adenine in herring sperm DNA was successfully applied with satisfactory results.     

Electrochemical properties of a tetrabromo-p-benzoquinone modified carbon paste electrode. Application to the simultaneous determination of ascorbic acid,dopamine and uric acid

The electrochemical study of a tetrabromo-p-benzoquinone modified carbon paste electrode (TBQ-MCPE), as well as its efficiency for electrocatalytic oxidation of ascorbic acid, dopamine and uric acid, is described. Cyclic voltammetry was used to investigate the redox properties of this modified electrode at various solution pH values and at various scan rates. Three linear segments were found with slope values of ?58.4 mV/pH, ?28.1 mV/pH and 0.0 mV/pH in the pH range 2.0–7.1, pH 7.1–9.0 and pH 9.0–11.0, respectively. The apparent charge transfer rate constant, k_s, and transfer coefficient, α, for electron transfer between TBQ and CPE were calculated as 3.79 ± 0.10 s^?1 and 0.55, respectively. The electrode was also employed to study the electrocatalytic oxidation of AA, using cyclic voltammetry, chronoamperometry and differential pulse voltammetry as diagnostic techniques. It has been found that the oxidation of AA at the surface of TBQ-MCPE occurs at a potential of about 430 mV less positive than that of an unmodified CPE. The diffusion coefficient of AA was also estimated using chronoamperometry. The kinetic parameters such as the electron transfer coefficient, α, and heterogeneous rate constant, $k_{\mathrm{h}}^{\prime }$, for oxidation of AA at the TBQ-MCPE surface was determined using cyclic voltammetry. Differential pulse voltammetry (DPV) exhibits two linear dynamic ranges and a detection limit of 0.62 μM for AA. In DPV, the TBQ-MCPE could separate the oxidation peak potentials of AA, DA and UA present in the same solution, though at the unmodified CPE the peak potentials were indistinguishable. This modified electrode was quite effective not only to detect AA, DA and UA, but also in simultaneous determination of each component concentration in the mixture.     

MWNT/Nafion composite modified glassy carbon electrode as the voltammetric sensor for sensitive determination of 8-hydroxyquinoline in cosmetic

In this paper, a multiwall carbon nanotube/Nafion composite modified glassy carbon electrode (MWNT/Nafion/GCE) was used as a voltammetric sensor to determine 8-hydroxyquinoline (8-HQ) in cosmetic. This voltammetric sensor exhibited strong catalytic effect toward the oxidation of 8-HQ and caused an anodic peak at 0.97 V in HAc-NaAc buffer solution (0.2 M, pH 3.6). Under the optimized condition, the anodic peak current was linear with the concentration of 8-HQ in the range of 2 × 10⁻⁸ M–1.0 × 10⁻⁵ M. The detection limit was 9 × 10⁻⁹ M. The practical application of MWNT/Nafion/GCE was carried out for determining 8-HQ in cosmetic sample with satisfactory results. The electrode reaction mechanism was studied by cyclic voltammetry and UV–vis spectra.     

Short-time preparation and electrochemical properties of a single layer of tetraoctylammonium bromide capped Au nanoparticles on dithiol self-assembled monolayer-modified Au electrode

Short time immobilization of densely packed tetraoctylammonium bromide (TOAB) stabilized gold nanoparticles (AuNPs) were established on a Au electrode modified with a self-assembled monolayer (SAM) of 1,6-hexanedithiol (HDT) or 1,4-benzenedimethanethiol (BDMT). The quartz crystal microbalance experiment showed densely packed TOAB–AuNPs single layer formation on both SAMs was achieved within 20 min. AFM images demonstrated that the immobilized TOAB–AuNPs on the SAMs were densely packed and the AuNPs film thickness was 6–7 nm. The electronic communication between the immobilized AuNPs and the underlying bulk electrode was confirmed by cyclic voltammetry and electroreflectance spectroscopy. A reversible electron transfer reaction was observed for both [Fe(CN)₆]^4−/3− and [Ru(NH₃)₆]^2+/3+ at TOAB–AuNPs immobilized on HDT (Au/HDT/AuNPs) and BDMT (Au/BDMT/AuNPs) modified electrodes. The electroreflectance spectra show a red-shifted strong positive-going plasmon resonance bands at 551 nm and 584 nm, respectively, for the Au/BDMT/AuNPs and Au/HDT/AuNPs electrodes. The observed reversible redox response for the solution redox species and red-shifted plasmon resonance bands for the immobilized AuNPs again indicated that the AuNPs were immobilized on the SAMs in a densely packed manner. An advantage of TOAB–AuNPs modified electrode prepared by short time immersion over citrate-stabilized AuNPs modified electrode was demonstrated by the enhanced oxidation of ascorbic acid (AA) at these electrodes. The oxidation of AA was shifted to 90 mV less positive potential with higher oxidation current at TOAB–AuNPs modified electrode when compared to citrate-stabilized AuNPs modified electrode.     

Facile growth of flower-like Au nanocrystals and electroanalysis of biomolecules

Growth of flower-like Au nanocrystals at room temperature on a conducting support and electroanalysis of biomolecules are described. The Au nanocrystals are grown by seed-mediated growth approach using electrochemically deposited Au nanoseeds (nAuS) without any template or surfactants. The flower-like nanocrystals (nAuF) have the size ranging from 75 to 350 nm. XRD profile of nAuF reveals the existence of (1 1 1), (2 0 0) and (3 1 1) planes, corresponding to the face centered cubic lattice of Au. The nAuF on the electrode surface have significantly large surface area of 0.354 ± 0.02 cm². The electroanalysis of biomolecules such as ascorbic acid (AA), dehydroascorbic acid (DHA), dopamine (DA) and reduced nicotinamide adenine dinucleotide (NADH) is performed using nAuF electrode. The nanocrystals on the electrode facilitate the oxidation of these bioanalytes; decrease in the overpotential and enhancement in the peak current is observed. Unlike the bulk Au electrode, nAuF electrode displays unique inverted ‘V’ shape voltammogram for NADH and DHA. Oxidation of AA occurs in two steps and two voltammetric peaks are obtained for AA in neutral and alkaline pH. Increase in the peak current and decrease in peak-to-peak separation with respect to the unmodified electrode are obtained for DA on nAuF electrode. The nAuF electrode shows high sensitivity, stability and linear response for a wide concentration range towards these analytes. The high sensitivity is ascribed to the ensemble behavior of the nAuF electrode.     

Preparation of perovskite-type composite oxide LaNi0.5Ti0.5O3–NiFe2O4 and its application in glucose biosensor

A novel nanostructured perovskite-type composite oxide LaNi_0.5Ti_0.5O₃–NiFe₂O₄ (LNT–NFO) was synthesized by sol–gel method and characterized by X-ray diffractometer (XRD) and transmission electron microscopy (TEM). Amperometric glucose biosensors based on the carbon paste electrode (CPE) were constructed by immobilizing glucose oxidase (GOD) with LNT–NFO and the experimental conditions such as the amount of GOD, pH value, and applied potential were investigated. Under the optimum conditions, the electrochemical performances of the LNT–NFO with different ratios of LNT-NFO (10:1, 20:1, 30:1) modified CPE have been researched on the oxidation of glucose. The results show that LNT–NFO (20:1) can immobilize GOD more effectively. The biosensor based on LNT–NFO/CS/GOD modified CPE exhibits good reproducibility, stability and selectivity in glucose determination with linear signal-to-glucose concentration range of 0.5–10 mM and a detection limit (S/N = 3) of 0.04 mM.     

Selective determination of dopamine using unmodified,exfoliated graphite electrodes

Selective determination of a neurotransmitter, dopamine (DA), is achieved in the presence of ascorbic acid (AA) at neutral pH on an inert, unmodified exfoliated graphite electrode. The edge planes, exposed by roughening the surface of the electrode have been found to be very active for electrochemical sensing. A separation of 0.24 V in the oxidation potential and an increase of 100 times in the currents between DA and AA have been observed with the graphite exfoliated at 800 °C. The exfoliation temperature is found to play a major role in determining the activation of the surface and in turn the effective separation of the analytes. This is attributed to the trend in the O/C ratios on the graphite electrodes observed using X-ray photoelectron spectroscopy. The separation is mainly due to the repulsive interactions between the functional groups on the electrode surface and the ascorbate anion. This is confirmed by comparing the point of zero charge (pH_PZC) of the electrode surface determined using pH titration and the pK_a of AA. A very low detection limit of 50 nM of DA in the presence of 100 μM ascorbic acid has been observed using chronoamperometry. The exfoliated graphite is an unmodified electrode and hence just polishing the electrode could expose the active surface. The analytical utility of the exfoliated graphite electrodes for the selective determination of DA in the presence AA is presented.     

Selective detection of dopamine based on the unique property of gold nanofilm

Gold nanofilm, with a nanoporous morphology, was found to have the unique property to catalyze the oxidization of ascorbic acid (AA) and dopamine (DA), resulting in the improved electrochemical behavior of the two species and a negative shift of the oxidization potential of AA for about 300 mV. The catalytic oxidization of gold nanofilm to AA is mainly ascribed to its high surface energy, while the enhanced electron transfer ability of DA on the gold nanofilm is attributed to the strong interaction between DA and the electrode surface. Based on the peak separation of DA and AA, selective detection of DA was achieved on the gold nanofilm modified electrode. Differential pulse voltammetry (DPV) techniques and cyclic voltammetry (CV) were used to investigate the electrochemical behavior of AA and DA on the surface of the electrode. Afterwards, the obtained gold nanofilm was applied in selective detection of dopamine (DA) in the presence of ascorbic acid (AA) at near neutral pH by DPV in the optimized conditions. The linear range for DA was 1.5–27.5 μM. The electrode also shows good stability during detection.     

Kinetics of oxygen reduction on gold nanoparticle/multi-walled carbon nanotube hybrid electrodes in acid media

In this paper, the electrochemical reduction of oxygen has been studied on gold nanoparticle/multi-walled carbon nanotube (AuNP/MWCNT) modified glassy carbon (GC) electrodes in 0.5 M H₂SO₄ using the rotating disk electrode (RDE) method. The AuNP/MWCNT catalysts were prepared by chemical deposition of AuNPs onto MWCNTs spontaneously grafted with 4-nitrophenyl groups. The composite electrode was characterised by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). The oxygen reduction behaviour of these electrodes was compared with that of a bulk gold electrode. The AuNP/MWCNT catalyst showed a pronounced electrocatalytic activity towards O₂ reduction in acid media. The half-wave potential of O₂ reduction on the AuNP/MWCNT catalyst shifted ca 80 mV to more positive potentials as compared to that of a polished Au electrode. The kinetic parameters of oxygen reduction were determined and the specific activity of the hybrid electrode was slightly higher than that of the bulk Au electrode.     

Voltammetric sensor based on ordered mesoporous carbon for folic acid determination

With ordered mesoporous carbon (OMC) as the modifier, a voltammetric sensor for folic acid (FA) was constructed on a glassy carbon electrode (GCE). Due to the good characteristics of OMC, FA exhibited an enhanced electrochemical response and lower reduction potential in the neutral solution. In addition, the experimental parameters such as pH values, accumulation time and potential were optimized. Using the differential pulse voltammetry (DPV) measurement, the peak current was found to be linear with FA concentration in the range from 5.0 × 10⁻¹⁰ to 1.0 × 10⁻⁷ M with a lower detection limit of 6.0 × 10⁻¹¹ M (S/N = 3). Also, in real samples analysis, the as-prepared sensor successfully gives satisfying results.