Film-modified Glassy Carbon Electrode Research Articles

Voltammetric determination of trace heavy metals using an electrochemically deposited graphene/bismuth nanocomposite film-modified glassy carbon electrode

A novel electrochemically deposited graphene (EG)/bismuth (Bi) nanocomposite film-modified glassy carbon electrode (GCE) was prepared through successive electrodeposition of exfoliated graphene oxide (GO) and in situ plating bismuth film. Experimental variables, including deposition potential and bismuth concentration, were carefully optimized to determine trace zinc, cadmium, and lead ions by using the EG/Bi electrode as an electrochemical-sensing platform. The linear calibration curves ranged from 1 to 100μgL−1 for Zn2+, Cd2+, and Pb2+. The detection limits were 1.80μgL−1 for Zn2+, 0.18μgL−1 for Cd2+, and 0.11μgL−1 for Pb2+ (S/N=3). The EG/Bi nanocomposite film electrode was successfully applied to the analysis of trace metals in real environments.

Electrocatalytic behavior of glassy carbon electrode modified with ruthenium nanoparticles and ruthenium film

The electrocatalytic behavior of glassy carbon (GC) electrode modified with ruthenium nanoparticles and ruthenium film was studied for electrochemical reduction of nicotinamide adenine dinucleotide (NAD+). The surface of GC electrode was modified via cathodic deposition of nanosized ruthenium at different potentials. Scanning electron microscopy (SEM) images showed two kinds of surface morphologies based on deposition potential: Ru nanoparticles-decorated GC at −0.3 V and Ru film-coated GC at −0.5 V versus Ag/AgCl. The electrochemical behavior of Ru nanoparticles and Ru film-modified GC electrodes in phosphate buffer solution containing NAD+ was investigated using voltammetric techniques. A prominent cathodic peak was observed on bare GC and Ru nanoparticles-modified GC at −1.2 V versus Ag/AgCl which was related to NAD+ reduction. The electrochemical response of Ru film electrode was reversible, exhibiting a reduction peak at ca. −1.0 V and an oxidation peak at ca. −0.55 V which was attributed mainly to the hydrogen evolution reaction. Electrochemical impedance analysis indicated lower charge transfer resistance of Ru film electrode for hydrogen evolution as compared to GC and Ru nanoparticle electrodes. Ru film-modified electrode was found less reactive than the nanoparticles-modified GC electrode for NAD+ reduction reaction due to hydrogen evolution reaction that proceeds exclusively on Ru film.

Direct Electrochemical Determination of Methyl Jasmonate in Rice Floret at a Iron-Porphyrin Film Modified Glassy Carbon Electrode by Square Wave Voltammetry

Direct Electrochemical Determination of Methyl Jasmonate in Rice Floret at a Iron-Porphyrin Film Modified Glassy Carbon Electrode by Square Wave Voltammetry

Electrochemical enhancement of long alkyl-chained surfactants for sensitive determination of tetrabromobisphenol A

Three types of hydrophobic surfactants with one, two and three C18-alkyl chains, including octadecyltrimethylammonium bromide (OTMA), dioctadecyldimethylammonium bromide (DODMA) and trioctadecylmethylammonium bromide (TOMA), were used to construct sensing films for tetrabromobisphenol A (TBBPA). In pH 4.6 acetate buffer, an oxidation peak with low height is observed for TBBPA on the surface of glassy carbon electrode (GCE), and the oxidation wave increases greatly on the surfactant film-modified GCEs. Surface morphology analysis reveals that the modification of surfactants on GCE increases the surface roughness and introduces three-dimensional structures. Experiments of electrochemical impedance spectroscopy and chronocoulometry indicate that the electron transfer ability and accumulation efficiency of TBBPA enhance effectively on the surface of surfactant films. Moreover, the signal enhancement ability of surfactant films is heavily dependent on the molecular structures, and DODMA film is more active for the oxidation of TBBPA. As a result, a sensitive and simple electrochemical sensing platform was developed for TBBPA. The linear range is from 1.0 to 500μgL−1, and the detection limit is 0.57μgL−1 (1.05nM). This new sensing system has been used to detect TBBPA in e-waste samples, and the results consist with the values that obtained by high-performance liquid chromatography.

Square wave voltammetric detection by direct electroreduction of paranitrophenol (PNP) using an organosmectite film-modified glassy carbon electrode

This work describes the development of a low-cost and reliable adsorptive stripping voltammetric method for the detection of PNP in water. Organoclays were prepared by intercalation in various loading amounts of cetyltrimethylammonium ions (CTA+) in the interlayer space of a smectite-type clay mineral. Their structural characterization was achieved using several techniques including X-ray diffraction (XRD), N2 adsorption–desorption (BET method) and Fourier Transform Infrared spectroscopy (FTIR) that confirmed the intercalation process and the presence of the surfactant ions within the clay mineral layers. Using [Fe(CN)6]3− and [Ru(NH3)6]3+ as redox probes, the surface charge and the permeability of the starting clay mineral and its modified counterparts were assessed by multisweep cyclic voltammetry, when these materials were coated on the surface of a glassy carbon electrode (GCE). In comparison with the bare GCE, the organoclay modified electrodes exhibited more sensitive response towards the reduction of paranitrophenol (PNP). Under optimized conditions, a calibration curve was obtained in the concentration range from 0.2 to 5.2µmolL−1; leading to a detection limit of 3.75×10−8molL−1 (S/N=3). After the study of some interfering species on the electrochemical response of PNP, the developed sensor was successfully applied to the electroanalytical quantification of the same pollutant in spring water.

Voltammetric Determination of Folic Acid Using Adsorption of Methylene Blue onto Electrodeposited of Reduced Graphene Oxide Film Modified Glassy Carbon Electrode

AbstractThis work presents a sensitive voltammetric method for determination of folic acid by adsorbing methylene blue onto electrodeposited reduced graphene oxide film modified glassy carbon electrode (MB/ERGO/GCE) in 100 mM KCl‐10 mM sodium phosphate buffer solution (pH 7.40). The surface morphology of the MB/ERGO/GCE modified electrode was characterized using scanning electron microscopy, displays that both MB and ERGO distributed homogeneously on the surface of GCE. The MB/ERGO/GCE modified electrode shows more favorable electron transfer kinetics for potassium ferricyanide and potassium ferrocyanide probe molecules, which are important electroactive compounds, compared with bare GCE, MB/GCE, and ERGO/GCE. The electrochemical behaviors of folic acid at MB/ERGO/GCE were investigated by cyclic voltammetry, suggesting that the modified electrode exhibited excellent electrocatalytic activity towards folic acid compared with other electrodes. Under physiological condition, the MB/ERGO/GCE modified electrode showed a linear voltammetric response from 4.0 μM to 167 μM for folic acid, and with the detection limit of 0.5 μM (S/N=3). The stability, reproducibility and anti‐interference ability of the modified electrode were examined. The developed method has been successfully applied to determination of FA in tablets with a satisfactory recovery from 96 % to 100 %. The work demonstrated that the electroactive MB adsorbing onto graphene modified electrode showed an enhanced electron transfer property and a high resolution capacity to FA.

High-performance electrochemical amperometric sensors for the sensitive determination of phenyl urea herbicides diuron and fenuron

We have described the fabrication of high-performance amperometric sensors derived from graphene oxide–multiwalled carbon nanotube (GO–MWCNT) composite for the sensitive determination of diuron and fenuron. GO–MWCNT composite was prepared by simple solution-based approach, and its formation was confirmed by scanning electron microscopy, transmission electron microscopy and UV-visible spectroscopy methods. GO–MWCNT film-modified glassy carbon electrode exhibited excellent electrocatalytic performance in the oxidation of diuron and fenuron in terms of less overpotential and highly enhanced peak currents. GO–MWCNTs have presented significantly improved electrocatalytic performance than dimethylformamide-dispersed MWCNTs. GO–MWCNT-based amperometric sensor has been fabricated which detects diuron in wide linear range between 9 μM and 0.38 mM with high sensitivity of 0.645 μA μM−1 cm−2. The amperometric sensor also detects fenuron in broad linear range between 0.9 and 47 μM with sensitivity of 1.20 μA μM−1 cm−2. Moreover, the sensor offers appreciable repeatability, reproducibility, and stability results. Practical feasibility of the prepared amperometric sensor has been assessed in various water samples collected from agricultural areas.

Construction of a non-enzymatic glucose sensor based on copper nanoparticles/poly(o-phenylenediamine) nanocomposites

An electrochemical non-enzymatic glucose sensor was fabricated by electrodeposition of copper nanoparticles (CuNPs) onto a poly(o-phenylenediamine) (PoPD) film-modified glassy carbon electrode (CuNPs/PoPD/GCE). We had studied some factors such as the pH value of supporting electrolyte, the amount of PoPD and applied potentials and optimize the experiment conditions. Under the optimum conditions, the as-obtained sensor for glucose sensing had achieved a wide linear range, low detection limit, and fast response time. The current response of the as-obtained sensor towards electrochemical oxidation of glucose was linear with the concentration of glucose in the range of 5.0 μM to 1.6 mM (R = 0.998) in the solution of 0.1 M NaOH at the applied potential of 0.5 V. The detection limit is 0.25 μM and the fast response achieves within 1 s. The sensor exhibits good sensitivity, selectivity, and reproducibility. The proposed non-enzymatic glucose was successfully employed to determine glucose in blood samples.

Electrochemical Determination of Phenolic Acids at a Zn/Al Layered Double Hydroxide Film Modified Glassy Carbon Electrode

AbstractA stable sensor for the determination of gallic acid (GA) and caffeic acid (CA) was fabricated by electrodeposition of Zn‐Al‐NO3 layered double hydroxide film on a glassy carbon electrode (LDHf/GCE). A sensitive electrochemical method was achieved for the determination of GA and CA in a phosphate buffer solution (pH 3). The differential pulse voltammetry response of the LDHf/GCE to GA has a linear concentration range from 4 µM to 600 µM with a correlation coefficient of 0.9985 and the calculated detection limit of 1.6 µM at a signal‐to‐noise ratio of 3. The differential pulse voltammetry response of the LDHf/GCE to CA has a linear concentration range from 7 µM to 180 µM with a correlation coefficient of 0.9969 and the calculated detection limit of 2.6 µM at a signal‐to‐noise ratio of 3. The constructed sensor was applied to the determination of GA in commercial green tea samples.

Preparation of three-dimensionally ordered macroporous polycysteine film and application in sensitive detection of 4-chlorophenol

Polystyrene microspheres with diameter of 350nm were prepared, and then used to arrange on the surface of glassy carbon electrode (GCE) as structure-directing template. By successive cyclic sweeps between −1.0V and 2.0V in pH 7 phosphate buffer containing 10mM cysteine, polycysteine film was electrodeposited on polystyrene microspheres-arranged GCE. After removing polystyrene template, a three-dimensionally ordered macroporous (3-DOM) polycysteine film was achieved, as confirmed by scanning electron microscopy measurements. Electrochemical responses of K3[Fe(CN)6] probe indicated that 3-DOM polycysteine film-modified GCE exhibited larger active area, compared with GCE, polycysteine film-modified GCE and electrochemically oxidized GCE. The application of 3-DOM polycysteine film in electrochemical detection of 4-chlorophenol was studied. Due to ordered porous structures, the 3-DOM polycysteine film-modified GCE displayed signal enhancement effects, and enhanced the oxidation peak currents of 4-chlorophenol. As a result, a sensitive electrochemical method was developed for the detection of 4-chlorophenol, and the detection limit was 1.67×10−8M. This new method was used to detect 4-chlorophenol in water samples, and the value of recovery was over the range from 99.6% to 107%.

Electrochemical oxidation behavior of 8-azaguanine at graphene-Nafion composite film-modified glassy carbon electrode

A simple but highly sensitive electrochemical sensor for the determination of 8-azaguanine based on graphene-Nafion nanocomposite film-modified glassy carbon electrode (G-Nafion/GCE) was reported. The electrochemical behaviors of 8-azaguanine at G-Nafion/GCE were investigated by cyclic voltammetry (CV), square wave voltammetry (SWV), chronoamperometry (CA), and chronocoulometry (CC). The results showed that the electrochemical sensor exhibited excellent electrocatalytic activity to 8-azaguanine. 8-Azaguanine can be effectively accumulated at G-Nafion/GCE and produce a sensitive anodic peak, due to the synergetic functions of graphene and Nafion. Under the selected conditions, the modified electrode in pH 1.98 Britton-Robinson buffer solution showed a linear voltammetric response to 8-azaguanine within the concentration range of 5.0 × 10−8∼3.0 × 10−5 mol L−1, with the detection limit of 1.0 × 10−8 mol L−1. And, the method was also applied to detect 8-azaguanine in spiked human urine with wonderful satisfactory results.

A sensitive sensor for determination of l-tryptophan based on gold nanoparticles/poly(alizarin red S)-modified glassy carbon electrode

This work described a novel sensor for detection of l-tryptophan (Trp) by electrodeposition of gold nanoparticles (AuNPs) onto the poly(alizarin red S) film pre-cast on a glassy carbon electrode (GCE). Alizarin red S (ARS) was deposited on the surface of the GCE by electropolymerization, and gold nanoparticles (AuNPs) were attached onto the poly(ARS) film by electrodeposition, forming an AuNPs–PARS nanocomposite film-modified GCE (AuNPs–PARS/GCE). Then electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were used to characterize modified electrodes. The Nyquist diagrams of EIS indicated that the PARS film and AuNPs were successfully immobilized on the surface of GCE, and the electron transfer resistance value of electrode changed efficiently. The SEM image showed that the immobilized AuNPs were spherical in shape. The AuNPs–PARS/GEC displayed excellent amperometric response for Trp. The amperometric responses have two linear ranges from 0.02 to 0.5 μM and 0.5 to 20.0 μM, with sensitivities of 1.63(±0.08) and 0.21(±0.01) μAμM−1, respectively. Its detection limit was 6.7 nM at a signal-to-noise ratio of 3. The proposed method was applied to determine Trp.

Voltammetric determination of alkannin using an Au nanoparticles–poly(diallyldimethylammonium chloride)-functionalized graphene nanocomposite film

An electrochemical sensor based on Au nanoparticles (AuNPs)–poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (AuNPs–PDDA-G) nanocomposite was fabricated for the sensitive detection of alkannin. The nanocomposite was characterized by X-ray diffraction, ultraviolet/visible spectra, scanning electron microscopy, and transmission electron microscopy. Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behaviors of alkannin on the AuNPs–PDDA-G nanocomposite film-modified glassy carbon electrode. This electrochemical sensor displayed satisfactory analytical performance for alkannin detection over a range from 5.0 nmol L−1 to 3.0 μmol L−1 with a detection limit of 1.4 nmol L−1 (S/N = 3). Moreover, the sensor also exhibited good reproducibility and stability, and could be used for the detection of alkannin in real samples with satisfactory results.

An Immunosensor for Ultrasensitive Detection of 1‐Pyrenebutyric Acid with Enhanced Electrochemical Performance Based on a Graphene‐Ionic Liquid Doped Chitosan Film Modified Glassy Carbon Electrode

AbstractThis paper describes a highly sensitive and label‐free electrochemical immunosensor for the detection of 1‐pyrenebutyric acid (PBA) which is based on a graphene (GS), chitosan (CS), and ionic liquid (IL) composite modified glassy carbon electrode (GS‐CS‐IL/GCE). The modification process was monitored by transmission electron microscopy (TEM) and cyclic voltammetry (CV). Due to the synergistic effects of GS, CS, and IL, the biosensor exhibits excellent selectivity to PBA. The current response of the proposed immunosensor decreases linearly at two concentration ranges from 0.01 to 5 and from 5 to 150 ng mL−1 with a detection limit of 0.01 ng mL−1.

Determination of Tetracycline at a UV‐Irradiated DNA Film Modified Glassy Carbon Electrode

AbstractIn this study, interaction of tetracycline (TC) and DNA in the BrittonRobinson buffer solution (BR) was studied by cyclic voltammetry. The experimental results reveal that TC can bind strongly to DNA and the association constant and binding number between TC and DNA was obtained. Then DNA was immobilized on a glassy carbon electrode by UV‐irradiation. Through this process, water‐soluble DNA was converted into insoluble materials, and a stable DNA film was formed on the electrode. The electrochemical oxidation behavior of TC was studied at UV‐irradiated DNA film modified glassy carbon electrode (UV‐DNA‐GCE). The response of modified electrode was optimized with respect to pH, accumulation time, ionic strength, drug concentration and other variables. TC at the surface of modified electrode showed a linear dynamic range of 0.30–90.00 µM and a detection limit of 0.27 µM. To demonstrate the applicability of the modified electrode, it was used for the analysis of real samples such as pharmaceutical formulations and milk.

An Electrochemical Approach to Simultaneous Determination of Acetaminophen and Ofloxacin

This study presents a simple electrochemical approach for preparing a poly(L-serine) film-modified glassy carbon electrode, which responds quickly and sensitively during the simultaneous determination of acetaminophen and ofloxacin in prepared, environmental, and pharmaceutical samples. The prepared electrode exhibited catalytic activities and promoted the oxidation of acetaminophen and ofloxacin. Acetaminophen and ofloxacin showed linear responses between 1.0 × 10(-5) and 1.0 × 10(-4) mol/L and their limits of detection were 1.2 × 10(-7) and 1.6 × 10(-7) mol/L, respectively. The average recoveries (± relative standard deviations) of acetaminophen and ofloxacin were 96.8 ± 3.5 % and 97.6 ± 3.2 %, respectively, indicating that the prepared electrode and detection method are very accurate and reproducible for the simultaneous determination of acetaminophen and ofloxacin.

A method based on electrodeposition of reduced graphene oxide on glassy carbon electrode for sensitive detection of theophylline

Graphene nanosheets were directly electrodeposited onto a glassy carbon electrode (GCE) from the electrolyte solution containing graphene oxide (GO); the resulting electrode (ED-GO/GCE) was characterized with scanning electron microscopy. A simple and rapid electrochemical method was developed for the determination of theophylline (TP), based on the excellent properties of ED-GO film. The result indicated that ED-GO film-modified GCE exhibited efficient electrocatalytic oxidation for TP with relatively high sensitivity and stability. The electrochemical behavior of TP at ED-GO/GCE was investigated in detail. Under the optimized conditions, the oxidation peak current was proportional to the TP concentration in the range of 8.0 × 10−7 to 6.0 × 10−5 mol L−1 with the detection limit of 1.0 × 10−7 mol L−1 (S/N = 3). The proposed method was successfully applied to green tea samples with satisfactory results.

An amperometric sensor for the determination of benzophenone in food packaging materials based on the electropolymerized molecularly imprinted poly-o-phenylenediamine film

Benzophenone is one of the most commonly used photoinitiators of UV-cured inks on food packaging materials and can migrate into foodstuffs. In this study, an amperometric benzophenone sensor based on molecularly imprinted polymer (MIP) was successfully constructed for the first time. The sensor was prepared by electropolymerizing o-phenylenediamine (o-PD) on a glassy carbon electrode (GCE) in the presence of template benzophenone, and then removing the template by immersing the poly-o-phenylenediamine film-modified GCE in ethanol. The molecularly imprinted sensor was tested in the presence or absence of benzophenone by cyclic voltammetry and linear sweep voltammetry to verify the changes in the redox peak currents of potassium ferricyanide. The sensor responded sensitively to benzophenone over a linear range of 0.05–5μM with a detection limit of 10nM. The imprinted sensor showed high recognition ability for benzophenone and was successfully applied to the determination of benzophenone in food packaging material samples.

Electrochemical determination of methyl parathion using poly(malachite green)/graphene nanosheets–nafion composite film-modified glassy carbon electrode

A novel poly(malachite green)/graphene nanosheets–nafion (PMG/GNs–NF) composite film-modified glassy carbon electrode was developed to indirectly detect methyl parathion (MP). p-nitrophenol, the alkaline hydrolysis product of MP, was successfully determined at a relatively lower potential using this modified electrode due to the excellent electrocatalytic activity of PMG/GNs–NF composite film. The presence of GNs in the composite film enhanced the stability of PMG and increased the electron transfer rate. The kinetic parameters of modified electrodes were studied. What is more, the optimum experimental parameters affecting response were selected in terms of pH, accumulation potential, accumulation time, scanning cycles during polymerization of malachite green, and alkaline hydrolysis conditions. Under optimum conditions, the chronoamperometric response current was proportional to MP concentration over the range from 0.02 to 1.5 μM with a low-detection limit of 2.0 nM. Finally, the sensor was applied for the determination of MP in real samples, and the results were satisfactory with recoveries from 97.20 to 104.53 %. Due to its simple preparation, good reproducibility, and stability, this developed modified electrode provides a new platform for the detection of organophosphate pesticides.

Enhanced oxidation and detection of toxic ractopamine using carbon nanotube film-modified electrode

Insoluble multi-walled carbon nanotube (MWCNT) was readily dispersed into water in the presence of dihexadecyl hydrogen phosphate, and then used to modify the surface of glassy carbon electrode (GCE) by means of solvent evaporation. Scanning electron microscopy test indicated that the GCE surface was coated with uniform MWCNT film. The resulting MWCNT film-modified GCE greatly enhanced the oxidation signal of ractopamine. The oxidation mechanism was studied, and it was found that the oxidation of ractopamine occurred at two phenolic hydroxyl groups, involving two protons and two electrons. Moreover, the influences of pH value, amount of MWCNT, accumulation potential and time were investigated on the oxidation signal of ractopamine. Based on the strong enhancement effect of MWCNT, a sensitive, rapid and simple electrochemical method was developed for the detection of ractopamine. The linear range was from 50μgL−1 to 2mgL−1, and the detection limit was 20μgL−1. Finally, this method was successfully used to detect the content of ractopamine in pork and liver samples, and the recovery was in the range from 93.1% to 107.2%.