Differential pulse anodic stripping voltammetric determination of traces of tin using a glassy carbon electrode modified with bismuth and a film of poly(bromophenol blue)

We report on an anodic stripping voltammetric method for the determination of tin using a glassy carbon electrode modified with bismuth and poly(bromophenol blue). After an accumulation time of 60?s at ?1.20?V (vs. SCE), the response of the electrode to tin in 1.0?M HCl is linear in the concentration ranges from 20 nM to 1.0?μM, and from 1.0?μM to 20?μM, with a detection limit of 7.0 nM (at an SNR of 3) and with relative standard deviations in the order of 3.0–3.8%. The method was validated by comparing the results with those obtained by AAS and successfully applied to the determination of tin in canned food.

Underpotential Deposition Study and Determination of Bismuth on Gold Electrode by Using Voltammetry

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Electrode Modified with Langmuir–Blodgett (LB) Film of Calixarenes for Preconcentration and Stripping Analysis of Hg(II)

A new type of current sensor, Langmuir–Blodgett (LB) film of calixarene on the surface of glassy carbon electrode (GCE) was prepared for determination of mercury by anodic stripping voltammetry (ASV). An anodic stripping peak was obtained at 0.15 V (vs. SCE) by scanning the potential from ?0.6 to +0.6 V. Compared with a bare GCE, the LB film coated electrode greatly improves the sensitivity of measuring mercury ion. The fabricated electrode in a 0.1 M H₂SO₄+0.01 M HCl solution shows a linear voltammetric response in the range of 0.07–40 μg L^?1 and detection limit of 0.04 μg L^?1 (ca. 2×10^?10 M). The high sensitivity, selectivity, and stability of this LB film modified electrode demonstrates its practical application for a simple, rapid and economical determination of Hg²⁺ in a water sample.     

Preparation of Cu (II) imprinted polymer electrode and its application for potentiometric and voltammetric determination of Cu (II)

The Cu (II) imprinted polymer glassy carbon electrode (GCE/Cu-IP) was prepared by electropolymerization of pyrrole at GCE in the presence of methyl red as a dopant and then imprinting by Cu²⁺ ions. This electrode was applied for potentiometric and voltammetric detection of Cu²⁺ ion. The potentiometric response of the electrode was linear within the Cu²⁺ concentration range of 3.9 × 10^?6 to 5.0 × 10^?2 M with a near-Nernstian slope of 29.0 mV decade^?1 and a detection limit of 5.0 × 10^?7 M. The electrode was also used for preconcentration anodic stripping voltammetry and results exhibited that peak currents for the incorporated copper species were dependent on the metal ion concentration in the range of 1.0 × 10^?8 to 1.0 × 10^?3 M and detection limit was 6.5 × 10^?9 M. Also the selectivity of the prepared electrode was investigated. The imprinted polymer electrode was used for the successful assay of copper in two standard reference material samples.     

Bismuth and Bismuth-Chitosan modified electrodes for determination of two synthetic food colorants by net analyte signal standard addition method

In this paper, an electrochemical application of bismuth film modified glassy carbon electrode for azo-colorants determination was investigated. Bismuth-film electrode (BiFE) was prepared by ex-situ depositing of bismuth onto glassy carbon electrode. The plating potential was ?0.78 V (vs. SCE) in a solution of 0.15 mg mL^?1 Bi(III) and 0.05 mg mL^?1 KBr for 180 s. In the next step, a thin film of chitosan was deposited on the surface of bismuth modified glassy carbon electrode, thus the bismuth-chitosan thin film modified glassy carbon electrode (Bi-CHIT/GCE) was fabricated and compared with bare GCE and bismuth modified GCE. Azo-colorants such as Sunset Yellow and Carmoisine were determined on these electrodes by differential pulse voltammetry. Due to overlapping peaks of Sunset Yellow and Carmoisine, simultaneous determination of them is not possible, so net analyte signal standard addition method (NASSAM) was used for this determination. The results showed that coated chitosan can enhance the bismuth film sensitivity, improve the mechanical stability without caused contamination of surface electrode. The Bi-CHIT/GC electrode behaved linearly to Sunset Yellow and Carmoisine in the concentration range of 5×10^?6 to 2.38×10^?4 M and 1×10^?6 to 0.41×10^?4 M with a detection limit of 10 µM (4.52 µg mL^?1) and 10 µM (5.47 µg mL^?1), respectively      

Fabrication of Bismuth/Multi-walled Carbon Nanotube Composite Modified Glassy Carbon Electrode for Determination of Cobalt

A bismuth/multi‐walled carbon nanotube (Bi/MWNT) composite modified electrode for determination of cobalt by differential pulse adsorptive cathodic stripping voltammetry is described. The electrode is fabricated by potentiostatic pre‐plating bismuth film on an MWNT modified glassy carbon (GC) electrode. The Bi/MWNT composite modified electrode exhibits enhanced sensitivity for cobalt detection as compared with the bare GC, MWNT modified and bismuth film electrodes. Numerous key experimental parameters have been examined for optimum analytical performance of the proposed electrode. With an adsorptive accumulation of the Co(II)‐dimethylglyoxime complex at ?0.8 V for 200 s, the reduction peak current is proportional to the concentration of cobalt in the range of 4.0×10^?10?1.0×10^?7 mol/L with a lower detection limit of 8.1×10^?11 mol/L. The proposed method has been applied successfully to cobalt determination in seawater and lake water samples.     

The electrochemical stripping determination of bismuth in aqueous and nonaqueous media after its extraction

The cyclic voltammetry of bismuth in aqueous media and electrochemical stripping determination of bismuth in aqueous and nonaqueous media after its extraction using a rotating disc electrode of glassy carbon was studied. To raise the conductivity of the organic medium and for the preparation of a convenients medium for the determination of bismuth, an alcoholic (methanol) solution of NH₄SCN+HClO₄ was employed. In non-aqueous medium bismuth can be determined down to concentrations 10^?8M by anodic stripping voltammetry and to 5×10^?8M by anodic stripping chronopotentiometry. The selectivity of the determination of bismuth after its extraction was studied. Electrochemical determination of 10^?6M Bi³⁺ with error ±3–4% was not interfered with by these elements: Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, As³⁺ in the concentration 8×10^?3M, Fe³⁺, In³⁺, Sn²⁺ and Sn⁴⁺ (5× 10^?3M), Cu²⁺ (10^?3M), Sb³⁺ (1.5×10^?4M) and Hg²⁺ (2×10^?5M). The reproducibility of the electrochemical determination of bismuth according to the recommended procedure is very good.     

Sensitive Determination of Clomipramine at Poly‐ABSA/Pt Nano‐Clusters Modified Glassy Carbon Electrode

Abstract

Clomipramine, an important tricylic antidepressant drug with low redox activity, was effectively electrocatalyzed on poly‐aminobenzene sulfonic acid/Pt nano‐clusters modified glassy carbon electrode (i.e., poly‐ABSA/Pt/GCE) and generated a sensitive anodic peak at about 0.80 V in pH 8.1 PBS. ABSA was electropolymerized on the surface of GCE modified with Pt nano‐clusters. Pt nanoparticles provide a 3 D and conductive structure for the polymer immobilization. The resulting sensor exhibited a considerable enhancement in voltammetric response characteristics: extending the linear range and lowering the detection limit. The anodic peak current of clomipramine was linear with its concentration over two concentration intervals, viz., 1.0×10^?7～4.0×10^?6 M and 4.0×10^?6～4.0×10^?5 M, with the detection limit of 1.0×10^?9 M (S/N=3). This method was successfully applied to the determination of clomipramine in drug tablets and proved to be reliable compared with UV.     

Xanthine Sensors Based on Anodic and Cathodic Detection of Enzymatically Generated Hydrogen Peroxide

A xanthine biosensor was fabricated by the covalent immobilization of xanthine oxidase (XO) onto a functionalized conducting polymer (Poly‐5, 2′: 5′, 2″‐terthiophine‐3‐carboxylic acid), poly‐TTCA through the formation of amide bond between carboxylic acid groups of poly‐TTCA and amine groups of enzyme. The immobilization of XO onto the conducting polymer (XO/poly‐TTCA) was characterized using cyclic voltammetry, quartz crystal microbalance (QCM), and X‐ray photoelectron spectroscopy (XPS) techniques. The direct electron transfer of the immobilized XO at poly‐TTCA was found to be quasireversible and the electron transfer rate constant was determined to be 0.73 s^?1. The biosensor efficiently detected xanthine through oxidation at +0.35 V and reduction at ?0.25 V (versus Ag/AgCl) of enzymatically generated hydrogen peroxide. Various experimental parameters, such as pH, temperature, and applied potential were optimized. The linear dynamic ranges of anodic and cathodic detections of xanthine were between 5.0×10^?6?1.0×10^?4 M and 5.0×10^?7 to 1.0×10^?4 M, respectively. The detection limits were determined to be of 1.0×10^?6 M and 9.0×10^?8 M with anodic and cathodic processes, respectively. The applicability of the biosensor was tested by detecting xanthine in blood serum and urine real samples.     

Catalytic Adsorptive Stripping Voltammetry of Cobalt in the Presence of Nitrite at an In Situ Plated Bismuth Film Electrode

For the first time an in situ plated bismuth film electrode has been applied to catalytic adsorptive stripping voltammetry of cobalt in the presence of nitrite. At optimised conditions bismuth film was plated before each measurement for 30 s at ?1.0 V from a sample solution with the added supporting electrolyte and Bi(III) in the form of its complex with tartrate. The calibration graph for Co(II) for an accumulation time of 120 s was linear from 5×10^?10 to 1×10^?8 mol L^?1. The detection limit was 1.1×10^?10 mol L^?1. The proposed procedure was applied for Co(II) determination in certified water reference material.     

The Fabrication and Characterization of a Bismuth Nanoparticle Modified Boron Doped Diamond Electrode and Its Application to the Simultaneous Determination of Cadmium(II) And Lead(II)

We report the simultaneous electroanalytical determination of Pb²⁺ and Cd²⁺ by square‐wave anodic stripping voltammetry (SWASV) using a bismuth nanoparticle modified boron doped diamond (Bi‐BDD) electrode. Bi deposition was performed in situ with the analytes, from a solution of 0.1 mM Bi(NO₃)₃ in 0.1 M HClO₄ (pH 1.2), and gave detection limits of 1.9 μg L^?1 and 2.3 μg L^?1 for Pb(II) and Cd(II) respectively. Pb²⁺ and Cd²⁺ could not be detected simultaneously at a bare BDD electrode, whilst on a bulk Bi macro electrode (BiBE) the limits of detection for the simultaneous determination of Pb²⁺ and Cd²⁺ were ca. ten times higher.     

Determination of Trace Lead and Cadmium in Water Samples by Anodic Stripping Voltammetry with a Nafion‐Ionic Liquid‐Coated Bismuth Film Electrode

A new chemically modified bismuth film electrode coated with an ionic liquid [(1‐ethyl‐3‐methylimidazolium tetracyanoborate (EMIM TCB)] and Nafion was developed for the simultaneous determination Pb²⁺ and Cd²⁺ by anodic stripping voltammetry. Compared with conventional bismuth film electrodes, this electrode exhibited greatly improved electrochemical activity for Pb²⁺ and Cd²⁺ detection due to the unique properties of Nafion polymer and ionic liquid. The key experimental parameters related to the fabrication of the electrode and the voltammetric measurements were optimized on the basis of the stripping signals, where the peak currents increased linearly with the metal concentrations in a range of 10–120 µg L^?1 with a detect limit of 0.2 µg L^?1 for Pb²⁺, and 0.5 µg L^?1 for Cd²⁺ for 120s deposition. High reproducibility was indicated from the relative standard deviations (1.9 and 2.5 %) for nine repetitive measurements of 20 µg L^?1 Pb²⁺ and Cd²⁺, respectively. In addition, the surface characteristics of the modified BiFE were investigated by scanning electron microscopy (SEM), and results showed that fibril‐like bismuth nanostructures were formed on the porous Nafion polymer matrix. Finally, the developed electrode was applied to determine Pb²⁺ and Cd²⁺ in water samples, indicating that this electrode was sensitive, reliable and effective for the simultaneous determination of Pb²⁺ and Cd²⁺.     

Anodic Stripping Voltammetry Determination of Pb(II) and Cd(II) at a Bismuth/Poly(aniline) Film Electrode

Abstract

A novel voltammetric method—anodic—using a bismuth/poly(aniline) film electrode has been developed for simultaneous measurement of Pb(II) and Cd(II) at low µg L^?1 concentration levels by stripping voltammetry. The results confirmed that the bismuth/poly(aniline) film electrode offered high‐quality stripping performance compared with the bismuth film electrode. Well‐defined sharp stripping peaks were observed for Pb(II) and Cd(II), along with an extremely low baseline. The detection limits of Pb(II) and Cd(II) are 1.03 µg L^?1 and 1.48 µg L^?1, respectively. The bismuth/poly (aniline) electrode has been applied to the determination of Pb(II) in tap water samples with satisfactory results.     

Amperometric Sensor for Detection of the Reduced Form of Nicotinamide Adenine Dinucleotide Using a Poly(pyronin B) Film Modified Electrode

An electrochemical method for the preparation of poly(pyronin B) film was proposed in this paper. A poly(pyronin B) (poly(PyB)) film modified glassy carbon electrode (GCE) has been fabricated via an electrochemical oxidation procedure and applied to the electrocatalytic oxidation of reduced form of nicotinamide adenine dinucleotide (NADH). The poly(PyB) film modified electrode surface has been characterized by atomic force microscope (AFM), scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), UV‐visible absorption spectrophotometry (UV‐vis) and cyclic voltammetry (CV). These studies have been used to investigate the poly(PyB) film, which demonstrates the formation of the polymer film and the excellent electroactivity of poly(PyB) in neutral and even in alkaline media. Due to its potent catalytic effects towards the electrooxidation of NADH at lower potential (0.0 V), poly(PyB) film modified electrode can be used for the selective determination of NADH in real samples because of dopamine, ascorbic acid and uric acid oxidation can be avoided at this potential. The catalytic peak currents are linearly dependent on the concentrations of NADH in the range of 1.0×10^?6 to 5.0×10^?4 mol/L with correlation coefficients of 0.999. The detection limits for NADH is 0.5×10^?6 mol/L. Poly(PyB) modified electrode also shows good stability and reproducibility due to the irreversible attachment of polymer film at GCE surface.     

Voltammetric Determination of Adrenaline Using a Poly(1‐Methylpyrrole) Modified Glassy Carbon Electrode

A voltammetric method using a poly(1‐methylpyrrole) modified glassy carbon electrode was developed for the quantification of adrenaline. The modified electrode exhibited stable and sensitive current responses towards adrenaline. Compared with a bare GCE, the modified electrode exhibits a remarkable shift of the oxidation potentials of adrenaline in the cathodic direction and a drastic enhancement of the anodic current response. The separation between anodic and cathodic peak potentials (ΔEp) for adrenaline is 30 mV in 0.1 M phosphate buffer solution (PBS) at pH 4.0 at modified glassy carbon electrodes. The linear current response was obtained in the range of 7.5 × 10^?7 to 2.0 × 10^?4 M with a detection limit of 1.68 × 10^?7 M for adrenaline by square wave voltammetry. The poly(1‐methypyrrole)/GCE was also effective to simultaneously determine adrenaline, ascorbic acid and uric acid in a mixture and resolved the overlapping anodic peaks of these three species into three well‐defined voltammetric peaks in cyclic voltammetry. The modified electrode has been successfully applied for the determination of adrenaline in pharmaceuticals. The proposed method showed excellent stability and reproducibility.     

A novel palladium nanoparticles-polyproline-modified graphite electrode and its application for determination of curcumin

A novel-modified electrode has been developed, by electrodeposition of palladium nanoparticles (PdNps) on polypyroline film-coated (Poly(Pr)) graphite electrode. The modified electrode (PdNps/Poly(Pr)/GE) was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques. SEM proved that the palladium nanoparticles were uniform distributed with an average particle diameter of 20–45 nm. A higher catalytic activity was obtained for curcumin oxidation using this new modified electrode (PdNps/Poly(Pr)/GE). The square wave voltammogram of curcumin in pH 2 phosphate buffer exhibited an anodic peak at 0.504 V. This oxidation peak current was found to be linearly related to curcumin concentrations in the ranges of 5.0?×?10^?9 to 1.0?×?10^?7 M with a detection limit of 1.2?×?10^?9 M. This novel-modified electrode showed excellent sensitivity, compared with the existing reports about determination of curcumin.     

Catalytic Effect on Silver Electrodeposition of Gold Deposited on Carbon Electrodes

A new methodology, based on silver electrocatalytic deposition and designed to quantify gold deposited onto carbon paste electrode (CPE) and glassy carbon electrode (GCE), has been developed in this work. Silver (prepared in 1.0 M NH₃) electrodeposition at ?0.13 V occurs only when gold is previously deposited at an adequate potential on the electrode surface for a fixed period of time. When a CPE is used as working electrode, an adequate oxidation of gold is necessary. This oxidation is carried out in both 0.1 M NaOH and 0.1 M H₂SO₄ at oxidation potentials. When a GCE is used as working electrode, the oxidation steps are not necessary. Moreover, a cleaning step in KCN, which removes gold from electrode surface, is included. To obtain reproducibility in the analytical signal, the surface of the electrodes must be suitably pretreated; this electrodic pretreatment depends on the kind of electrode used as working electrode. Low detection limits (5.0×10^?10 M) for short gold deposition times (10 min for CPE and 5 min for GCE) were achieved with this novel methodology. Finally, sodium aurothiomalate can be quantified using silver electrocatalytic deposition and GCE as working electrode. Good linear relationship between silver anodic stripping peak and aurothiomalate concentration was found from 5.0×10^?10 M to 1.0×10^?8 M.     

Sensitive and Simple Electrochemical Detection of Lead(II) with Carbon Ionic Liquid Electrode

In this paper a carbon ionic liquid electrode (CILE) was fabricated by using ionic liquid 1‐ethyl‐3‐methylimidazolium ethylsulphate ([EMIM]EtOSO₃) as the modifier and further used as the working electrode for the sensitive anodic stripping voltammetric detection of Pb²⁺. The characteristics of the CILE were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In pH 4.5 NaAc‐HAc buffer Pb²⁺ was accumulated on the surface of CILE due to the extraction effect of IL and reduced at a negative potential (‐1.20 V). Then the reduced Pb was oxidized by differential pulse anodic stripping voltammetry with an obvious stripping peak appeared at ?0.67 V. Under the optimal conditions Pb²⁺ could be detected in the concentration range from 1.0 × 10^?8 mol/L to 1.0 × 10^?6 mol/L with the linear regression equation as I_p(μA) = ?0.103 C (μmol/L) + 0.0376 (γ = 0.999) and the detection limit as 3.0 × l0^?9 mol/L (3σ). Interferences from other metal ions were investigated and Cd²⁺ could be simultaneously detected in the mixture solution. The proposed method was further applied to the trace levels of Pb²⁺ detection in water samples with satisfactory results.     

Bismuth/Polyaniline/Glassy Carbon Electrodes Prepared with Different Protocols for Stripping Voltammetric Determination of Trace Cd and Pb in Solutions Having Surfactants

To improve reproducibility, stability and sensitivity, a bismuth (Bi) thin film was coated on glassy carbon (GC) substrates which surfaces were modified with a porous thin layer of polyaniline (PANI) via multipulse potentiostatic electropolymerization to form Bi/PANI/GC electrodes (Bi/PANI/GCEs). The Bi/PANI/GCEs were used successfully for simultaneous detection and determination of Cd²⁺ and Pb²⁺ ions, and various parameters were studied with reference to square wave anodic stripping voltammetric (SWASV) signals. The experimental results depicted that the environment‐friendly Bi/PANI/GCEs had the ability to rapidly monitor trace heavy metals even in the presence of surface‐active compounds.     

Selective Detection of Uric Acid in the Presence of Ascorbic Acid and Dopamine Using Polymerized Luminol Film Modified Glassy Carbon Electrode

Electrochemically polymerized luminol film on a glassy carbon electrode (GCE) surface has been used as a sensor for selective detection of uric acid (UA) in the presence of ascorbic acid (AA) and dopamine (DA). Cyclic voltammetry was used to evaluate the electrochemical properties of the poly(luminol) film modified electrode. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used for surface characterizations. The bare GCE failed to distinguish the oxidation peaks of AA, DA and UA in phosphate buffer solution (pH 7.0), while the poly(luminol) modified electrode could separate them efficiently. In differential pulse voltammetric (DPV) measurements, the modified GCE could separate AA and DA signals from UA, allowing the selective determination of UA. Using DPV, the linear range (3.0×10^?5 to 1.0×10^?3 M) and the detection limit (2.0×10^?6 M) were estimated for measurement of UA in physiological condition. The applicability of the prepared electrode was demonstrated by measuring UA in human urine samples.