Electrochemical Sensor For Simultaneous Determination Research Articles

An electrochemical sensor for simultaneous determination of ascorbic acid, dopamine, uric acid and tryptophan based on MWNTs bridged mesocellular graphene foam nanocomposite

A multi-walled carbon nanotubes (MWNTs) bridged mesocellular graphene foam (MGF) nanocomposite (MWNTs/MGF) modified glassy carbon electrode was fabricated and successfully used for simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (TRP). Comparing with pure MGF, MWNTs or MWNTs/GS (graphene sheets), MWNTs/MGF displayed higher catalytic activity and selectivity toward the oxidation of AA, DA, UA and TRP. Under the optimal conditions, MWCNs/MGF/GCE can simultaneously detect AA, DA, UA and TRP with high selectivity and sensitivity. The detection limits were 18.28µmolL−1, 0.06µmolL−1, 0.93µmolL−1 and 0.87µmolL−1, respectively. Moreover, the modified electrode exhibited excellent stability and reproducibility.

Construction and Application of an Electrochemical Sensor for Simultaneous Determination of Cd(II), Cu(II) and Hg(II) in Water and Foodstuff Samples

AbstractBy incorporation of synthesized magnetite nanoparticles (Fe3O4 NPs) coated with a new Schiff base into carbon paste electrode, a novel modified electrode was constructed for simultaneous determination of ultra trace amounts of Cd(II), Cu(II) and Hg(II). The complexation reaction of Schiff base with metal ions was studied spectrophotometrically. Under optimal conditions a detection limit of 0.20, 0.90 and 1.00 ng mL−1 for Cd(II), Cu(II) and Hg(II), respectively, was obtained. We take the advantages of the proposed method for simple, rapid, sensitive and selective simultaneous determination of trace amounts of hazardous Cd(II), Cu(II) and Hg(II) in water and foodstuff samples.

Fabrication of a nanostructure-based electrochemical sensor for simultaneous determination of epinephrine and tryptophan

A carbon-paste electrode modified with vinylferrocene and carbon nanotubes (CNTs) was used for the sensitive and selective voltammetric determination of epinephrine. The mediated oxidation of epinephrine at the modified electrode was investigated by cyclic voltammetry (CV). Square wave voltammetry (SWV) of epinephrine at the modified electrode exhibited two linear dynamic ranges with a detection limit of 3.0×10−8M. SWV was used for simultaneous determination of epinephrine and tryptophan at the modified electrode, and quantitation of epinephrine and tryptophan in some real samples by the standard addition method.

β-Cyclodextrin functionalized graphene material: A novel electrochemical sensor for simultaneous determination of 2-chlorophenol and 3-chlorophenol

In the present paper, a β-cyclodextrin (β-CD) functionalized graphene modified carbon paste electrode (CD/GRs/CPE) was prepared and characterized by atomic force microscopy (AFM), Fourier transform infrared (FT-IR) and electrochemical impedance spectroscopy (EIS). The electrochemical behaviors of 2-chlorophenol (2-CP) and 3-chlorophenol (3-CP) on different electrodes were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results demonstrated that the CD/GRs/CPE exhibited remarkable enhancement effects towards these two chlorophenols, especially for 3-CP. Importantly, their oxidation peaks could be well separated by CVs and DPVs. Under the optimized conditions, the oxidation peak currents displayed a good linear relationship to concentration in the ranges from 0.5 to 40μM for 2-CP and 0.4 to 77μM for 3-CP, with detection limits of 0.2 and 0.09μM, respectively. As a practical application, the proposed sensor was applied to quantitatively determine 2-CP and 3-CP in water samples with satisfying results.

An Electrochemical Sensor for Simultaneous Determination of Ponceau 4R and Tartrazine Based on an Ionic Liquid Modified Expanded Graphite Paste Electrode

A novel electrochemical sensing platform was designed for simultaneous determination of Ponceau 4R and Tartrazine using an ionic liquid modified expanded graphite paste electrode (IL-EGPE). The IL-EGPE was prepared by mixing ionic liquid-expanded graphite composite (IL-EG) with solid paraffin. Based on the advantageous functions of IL and EG, IL-EGPE showed excellent electrocatalytic activity toward the simultaneous oxidation of Ponceau-4R and Tartrazine. Due to the electrocatalytic activity to Ponceau-4R and Tartrazine, a sensor for Ponceau-4R and Tartrazine was constructed based on IL-EGPE. Under optimal experimental conditions, the designed sensor exhibited wide linear responses to Ponceau 4R and Tartrazine ranging from 1.0 × 10−8 to 5.0 × 10−6 mol/L and 1.0 × 10−8 to 2.0 × 10−6 mol/L, respectively. The detection limits for Ponceau 4R and Tartrazine were 1.4 × 10−9 mol/L (0.85 ng/mL) and 3.0 × 10−9 mol/L (1.6 ng/mL) at a signal-to-noise ratio of 3, respectively. This sensor showed good reproducibility, stability and reusability. The proposed sensor was successfully applied in the simultaneous determination of Ponceau-4R and Tartrazine in soft drink with satisfactory results.

Magnetic nanoparticles incorporated on functionalized mesoporous silica: an advanced electrochemical sensor for simultaneous determination of amiodarone and atenolol

A new chemically modified carbon paste electrode is constructed based on magnetic (Fe2O3) mobile crystalline material-41 grafted with 3-aminopropyl groups (MCM-41–nPrNH2), a kind of mesoporous silica with large surface area (362 m2 g−1). For the first time, the electrode was evaluated as an electrochemical sensor for simultaneous determination of amiodarone and atenolol in aqueous solutions. The measurements were carried out by application of the differential pulse voltammetry method in Briton Robinson buffer solution with pH 4.00. Fe2O3 loaded in MCM-41–nPrNH2 can increase anodic peak currents by adsorption of amiodarone and atenolol on the electrode surface. The prepared electrode shows voltammetric responses with good selectivity for amiodarone and atenolol in optimal conditions, which makes it suitable for simultaneous determination of these drugs.

Highly stable pyridinic nitrogen doped graphene modified electrode in simultaneous determination of hydroquinone and catechol

A highly stable pyridinic nitrogen doped graphene (pyridine-NG) was used as an excellent electrocatalyst for the construction of electrochemical sensor for simultaneous determination of hydroquinone (HQ) and catechol (CC) in 0.20M pH 5.5 acetate buffer solution. At the pyridine-NG modified electrode, both HQ and CC can cause a pair of quasi-reversible redox peaks and the potential difference of oxidation peaks between HQ and CC was 103mV. Under the optimized condition, the oxidation peak current of HQ was linear over the range from 5 to 200μM in the presence of 100μM CC, and the oxidation peak current of CC was linear over the range from 5 to 200μM in the presence of 100μM HQ. The detection limit is 0.38μM for HQ and 1μM for CC (S/N=3). This proposed sensor was successfully applied to the simultaneous determination of HQ and CC in artificial sample, and the results were good stability and high reproducibility. The excellent electrocatalysis of pyridine-NG can be due to the π–π interactions between the benzene ring of CC and graphene layer, the hydrogen bonds formed between hydroxyl in HQ molecule and pyridinic nitrogen atoms within graphene layers, especially the less density distribution of π electron cloud in pyridinic-NG in acidic condition.

Sensitive Electrochemical Sensor for Simultaneous Determination of Dopamine, Ascorbic Acid, and Uric Acid Enhanced by Amino-group Functionalized Mesoporous Fe3O4@Graphene Sheets

The electrochemical sensor based on amino-group functionalized mesoporous Fe3O4 (Fe3O4-NH2)@graphene sheets (GS) was constructed to simultaneously determine small biomolecules such as ascorbic acid (AA), dopamine (DA) and uric acid (UA). Due to the synergetic effect between GS and Fe3O4-NH2, the modified glassy carbon electrode not only improved the electrochemical catalytic oxidation of AA, DA, and UA, but also resolved the overlapping anodic peaks. Several important parameters controlling the performance of the electrochemical sensor were investigated and optimized. Using the modified electrode with differential pulse voltammetry (DPV) method, the linear response ranges for the determination of AA, DA, and UA were 5.0–1600μmolL−1, 0.2–38μmolL−1, and 1.0–850μmolL−1 in the co-existence systems of these three species under optimum condition, respectively. The detection limits (S/N=3) were found to be 0.074μmolL−1, 0.126μmolL−1, and 0.056μmolL−1 for the determination of AA, DA, and UA, respectively. Satisfactory results were achieved for the determination of DA, AA, and UA in DA hydrochloride injection, vitamin C injection, and human urine samples, respectively. The results imply that the electrochemical sensor has the advantages of simplicity, high sensitivity and good selectivity.

Electrochemical biosensor for sensitively simultaneous determination of dopamine, uric acid, guanine, and adenine based on poly-melamine and nano Ag hybridized film-modified electrode

An electrochemical sensor for simultaneous determination of dopamine (DA), uric acid (UA), guanine (G), and adenine (A) has been constructed by copolymerizing melamine monomer and Ag ions on a glassy carbon electrode (GCE) with cyclic voltammetry. The poly-melamine and nano Ag formed a hybridized film on the surface of the GCE. The morphology of the film was characterized by scanning electron microscope. The electrochemical and electrocatalytic properties of this film were characterized by cyclic voltammetry, linear sweep voltammetry, and square wave voltammetry (SWV). In 0.1 M phosphate buffer solution (pH 4.5), the modified electrode resolved the electrochemical response of DA, UA, G, and A into four well-defined voltammetric oxidation peaks by SWV; the oxidation peak current of DA, UA, G, and A increased 13-, 6-, 7-, and 9-fold, respectively, compared with those at the bare GCE and the SWV peak currents of DA, UA, G, and A with linear concentrations in the ranges of 0.1–50, 0.1–50, 0.1–50, and 0.1–60 μM, respectively. Based on this, a method for simultaneous determination of these species in mixture was setup. The detection limits were 10 nM for DA, 100 nM for UA, 8 nM for G, and 8 nM for A.

Nanomolar detection limit for determination of norepinephrine in the presence of acetaminophen and tryptophan using carbon nanotube-based electrochemical sensor

A carbon paste electrode modified by carbon nanotubes and a synthesized hydroquinone derivative (abbreviated as DHB) was fabricated. It was used as an electrochemical sensor for simultaneous determination of norepinephrine (NE), acetaminophen (AC), and tryptophan (Trp). Oxidation potential of NE decreased about 220 mV at the modified electrode in comparison with unmodified electrode because of electrocatalysis of oxidation of NE via EC mechanism at the modified electrode. Differential pulse voltammetry was used for obtaining the calibration plot of NE and two linear range of 0.2–20.0 μM and 20.0–1,500.0 μM and an interesting detection limit (3σ) of 40.0 nM were obtained for NE. Also, simultaneous determination of NE, AC, and Trp was described by the proposed sensor and linear range of 20.0–800.0 μM was found for AC and Trp. Finally, the electrochemical sensor was used for the determination of NE, AC, and Trp in mixture.

Electroactive species-doped poly(3,4-ethylenedioxythiophene) films: Enhanced sensitivity for electrochemical simultaneous determination of vitamins B2, B6 and C

Herein, functionalized PEDOT films were prepared by incorporation of two electroactive species, ferrocenecarboxylic acid (Fc−) and ferricyanide (Fe(CN)64−) as doping anions during the electropolymerization of PEDOT at glassy carbon electrodes (GCEs) from aqueous solution. The electrochemically synthesized electroactive species-doped PEDOT films have been carefully characterized by scanning electron microscopy (SEM), FTIR and UV/Vis spectra and various electrochemical techniques. Such nanostructured films combined the advantages of PEDOT (high conductivity and stability) together with electroactive species (good electrochemical activity) and were applied as electrochemical sensors for simultaneous determination of vitamin B2 (VB2), vitamin B6 (VB6) and vitamin C (VC). The results showed that the oxidation peak currents of vitamins obtained at the GCEs modified with electroactive species-doped PEDOT films were much higher than those at the ClO4−-doped PEDOT films and bare GCEs. The experiment results also illustrated that the sensors possessed high selectivity with no interference from other potential competing species. Moreover, the proposed sensors were successfully employed for the determination of vitamins in orange juice samples with satisfactory results.

Nanomolar simultaneous determination of levodopa and melatonin at a new cobalt hydroxide nanoparticles and multi-walled carbon nanotubes composite modified carbon ionic liquid electrode

A novel modified carbon ionic liquid electrode (CILE) is prepared as an electrochemical sensor for simultaneous determination of levodopa (l-Dopa) and melatonin (Mel). The experimental results suggest that a carbon ionic liquid electrode modified with multi-walled carbon nanotubes and cobalt hydroxide nanoparticles accelerates the electron transfer reactions of l-Dopa and Mel. The fabricated sensor revealed some advantages such as convenient preparation, good stability and high sensitivity. The DPV data in 0.1M phosphate buffer solution (PBS) (pH 7.5) allowed a method to be developed for the determination of l-Dopa and Mel concentrations in the ranges 0.1–300 and 0.01–50μM, with the detection limits of 0.075 and 0.004μM, respectively. The proposed method was successfully applied to determinations of these compounds in some pharmaceutical and human urine samples.

Nanomolar simultaneous determination of levodopa and serotonin at a novel carbon ionic liquid electrode modified with Co(OH)2 nanoparticles and multi-walled carbon nanotubes

A novel modified carbon ionic liquid electrode is prepared as an electrochemical sensor for simultaneous determination of levodopa (l-dopa) and serotonin (5-HT). The experimental results suggest that a carbon ionic liquid electrode modified with multi-walled carbon nanotubes and cobalt hydroxide nanoparticles, and coated with Nafion (Nafion/Co(OH)2–MWCNTs/CILE), accelerates the electron transfer reactions of l-dopa and 5-HT. In addition it shows no significant interferences of uric acid and ascorbic acid as electroactive coexistent compounds with l-dopa and 5-HT in biological systems. The fabricated sensor revealed some advantages such as convenient preparation, good stability and high sensitivity toward 5-HT and l-dopa determination. The DPV data showed that the obtained anodic peak currents were linearly dependent on the l-dopa and 5-HT concentrations in the range of 0.25–225 and 0.05–75μmolL−1, respectively. The applicability of the modified electrode was demonstrated by simultaneous determination of 5-HT and l-dopa in human serum.

Simultaneous electrochemical determination of ascorbic acid, dopamine and uric acid using poly (tyrosine)/functionalized multi-walled carbon nanotubes composite film modified electrode

A novel poly (tyrosine)/carboxyl functionalized multi-walled carbon nanotubes composite film modified electrode has been fabricated and used as electrochemical sensor for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The prepared electrode not only separated the cyclic voltammetric signals of AA, DA and UA with oxidation potential difference of 160 and 150mV between AA–DA and DA–UA, respectively but also showed higher oxidation current for these molecules in pH 7.4 phosphate buffer solution. Because it exhibited excellent selectivity towards the oxidation of AA, DA and UA, the modified electrode was used for simultaneous voltammetric measurement of the three analytes by differential pulse voltammetry. Under the optimum conditions, the detection limits for AA, DA and UA were 2.0μmolL−1, 0.02μmolL−1 and 0.30μmolL−1, respectively (S/N of 3). The method has good selectivity and sensitivity and was successfully applied to the simultaneous determination of AA, DA and UA in spiked human serum.

Application of thermally reduced graphene oxide modified electrode in simultaneous determination of dihydroxybenzene isomers

Thermally reduced graphene oxide (TRGO) was used as an excellent electrocatalyst for the construction of electrochemical sensor for simultaneous determination of dihydroxybenzene isomers including hydroquinone (HQ), catechol (CC) and resorcinol (RC). The surface morphology and structure of TRGO were investigated by utilizing transmission electron microscope, scanning electron microscopy, atomic force microscope, Raman spectroscopy and X-ray diffraction. The electrode modified with TRGO shows excellent electrocatalytic activity toward the oxidation of HQ, CC and RC. As a result, the oxidation peaks of three isomers in pH 6.0 PBS can be clearly discriminated due to large peak potential separation among them. In addition, HQ and CC can be simultaneously determined by using differential pulse voltammetry without any separation step. Under the optimized condition, the detection limits of HQ and CC are 0.75 and 0.8 μM (S/N = 3) with linear ranges of 1–500 μM in the presence of 50 μM isomer, respectively. The proposed method was successfully applied to the simultaneous determination of CC and HQ in synthetic water sample with reliable recovery. The proposed sensor has some important advantages such as low cost, ease of preparation, good stability and high reproducibility. Therefore, the present work promises for the application of graphene modified electrode in the simultaneous determination of multiple analytes.

A novel and simple strategy for simultaneous determination of dopamine, uric acid and ascorbic acid based on the stacked graphene platelet nanofibers/ionic liquids/chitosan modified electrode

A promising electrochemical sensor for simultaneous determination of dopamine (DA), uric acid (UA) and ascorbic acid (AA) was fabricated based on the stacked graphene platelet nanofibers (SGNF)/ionic liquid (IL)/chitosan (CS) modified electrode. The SGNF/IL/CS modified electrode possessed excellent electrocatalytic activity towards the oxidation of DA, UA and AA with obvious reduction of over-potential and increased peak current, and the separations of oxidation peak potentials of DA-UA, DA-AA, and UA-AA were of 151, 213 and 364mV, respectively. Under the optimum conditions, the linear range for the detection of DA, UA and AA were 0.05–240, 0.12–260, and 30–350μM with the lowest detection limits of 0.05, 0.10 and 14.8μM for DA, UA and AA, respectively. In addition, the electrochemical sensor showed high sensitivity, excellent selectivity, reproducibility and long-term stability.

Solvothermal synthesis of Cd(OH)2 and CdO nanocrystals and application as a new electrochemical sensor for simultaneous determination of norfloxacin and lomefloxacin

Cadmium hydroxide (Cd(OH)2) microcrystals were synthesized in ethanol–water medium by using cadmium chloride as cadmium source and 1,10-phenanthroline as complexation agent under solvothermal condition. The sample was characterized by FT-IR, X-ray diffraction (XRD), scanning electron microscopy (SEM) and TEM. The as-prepared Cd(OH)2 product were transformed to hexagonal CdO nanocubes by thermal treatment in air at 500°C. The possible growth mechanism for the formation of different morphologies at basic medium has been proposed. DPV experiments were carried out for the simultaneous determination of norfloxacin and lomefloxacin in the acetate buffer solution with pH 4.5.

Electrochemical sensor for simultaneous determination of norepinephrine, paracetamol and folic acid by a nanostructured mesoporous material

Abstract In this paper an electrochemical sensor was prepared by modification of carbon paste electrode with a nanostructured mesoporous material. The electrooxidation of norepinephrine (NE), paracetamol (AC) and folic acid (FA) was studied at this electrode by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). CV experiments showed that the oxidation overpotential of these substances decreased and their oxidation current increased sharply at the modified electrode rather than bare carbon paste electrode. The overlapped DPV peaks of NE, AC and FA has been resolved into three separated peaks by the electrochemical sensor. DPV peak currents increased linearly with concentration over the range of 7.0 × 10 −8 to 2.0 × 10 −3 , 5.0 × 10 −7 to 2.2 × 10 −3 and 5.0 × 10 −6 to 2.0 × 10 −3 M for NE, AC, and FA, respectively. Also, the proposed electrochemical sensor was used for the determination of these substances in some real samples.

Development of Electrochemical Sensor for Simultaneous Determination of Cd (II) and Hg (II) Ion by Exploiting Newly Synthesized Cyclic Dipeptide

Development of Electrochemical Sensor for Simultaneous Determination of Cd (II) and Hg (II) Ion by Exploiting Newly Synthesized Cyclic Dipeptide

Novel nanostructure-based electrochemical sensor for simultaneous determination of dopamine and acetaminophen

A carbon-paste electrode modified with a novel molybdenum (VI) complex and carbon nanotubes have been applied to the electrocatalytic oxidation of dopamine (DA) which reduced the overpotential by about 125 mV with obviously increase the current response. Due to its strong electrocatalytic activity towards DA, the modified carbon-paste electrode can resolve the overlapped voltammetric waves of DA and acetaminophen (AC) into two well-defined voltammetric peaks with peak-to-peak separation in potentials of about 230 mV. This property allows to selective determination of DA in the presence of AC. The transfer coefficient (a) for the electrocatalytic oxidation of DA and diffusion coefficient of this substance under the experimental conditions were also investigated. In phosphate buffer solution of pH 7.0, the oxidation current increased linearly with two concentration intervals of DA, one is 0.1 to 40.0 μM and, the other is 40.0 to 800.0 μM. The detection limit (3σ) obtained by DPV was 76.0 nM. The proposed method was successfully applied to the determination of DA, and AC in some commercial pharmaceutical samples.