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1.
Simultaneous Determination of Iron and Copper in Ethanol Fuel Using Nafion/Carbon Nanotubes Electrode
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This work presents the analytical method development for iron and copper determination in ethanol fuel. This method was developed using stripping voltammetry with a glassy carbon electrode modified with Nafion/Carbon‐nanotubes. With linear sweep stripping voltammetry was achieved a limit of detection of 7.1×10?7 mol L?1 for Fe3+ and 5.1×10?8 mol L?1 for Cu2+. The amperometric sensitivities were 2.0×106 µA mol?1 L for Fe3+ and 2.8×107 µA mol?1 L for Cu2+. The recovery study showed that the method has good accuracy and repeatability, with recovery of 108 and 103 % for Fe3+ and Cu2+ respectively. 相似文献
2.
L ‐Tyrosine can exhibit a small anodic peak on multiwalled carbon nanotubes (MWCNTs) coated glassy carbon electrodes (GCE). At pH 5.5 its peak potential is 0.70 V (vs. SCE). When an ionic liquid (i.e., 1‐octyl‐3‐methylimidazolium hexafluorophosphate, [omim][PF6]) is introduced on the MWCNT coat, the peak becomes bigger. Furthermore, in the presence of Cu2+ ion the anodic peak of L ‐tyrosine increases further due to the formation of Cu2+‐L ‐tyrosine complex, while the peak potential keeps unchanged. Therefore, a sensitive voltammetry based on the oxidation of Cu2+‐L ‐tyrosine complex on MWCNTs‐[omim][PF6] composite coated electrode is developed for L ‐tyrosine. Under the optimized conditions, the anodic peak current is linear to L ‐tyrosine concentration in the range of 1×10?8–5×10?6 M, and the detection limit is 8×10?9 M. The modified electrode shows good reproducibility and stability. In addition, the voltammetric behavior of other amino acids is explored. It is found that among them tryptophan (Trp) and histidine (His) can also produce sensitive anodic peak under same experimental conditions, and their detection limits are 4×10?9 M and 4×10?6 M, respectively. 相似文献
3.
《Analytical letters》2012,45(4):805-815
Abstract This paper describes a kinetic spectrophotometric method for the determination of L‐ascorbic acid (AA) and thiols (RSH). Absorbance of Fe(II)‐phen complex formed during the reaction of AA or RSH with Fe(III)‐phen was continuously measured at 510 nm by double‐beam spectrophotometer with flow cell. For determination some thiols, the catalytic effect of Cu2+ ions was used. AA and RSH can be determined in concentration ranges from 4.0×10?6 to 4.0×10?5 M and from 8.0×10?6 to 8.0×10?5 M, respectively. The applicability of the proposed method was demonstrated by determination of chosen compounds in pharmaceutical dosage forms. 相似文献
4.
Mojtaba Shamsipur Farhang Mizani Ali Akbar Saboury Hashem Sharghi Reza Khalifeh 《Electroanalysis》2007,19(5):587-596
Novel PVC membrane (PME) and coated graphite (CGE) Cu2+‐selective electrodes based on 5,6,7,8,9,10‐hexahydro‐2H‐1,13,4,7,10‐benzodioxatriazacyclopentadecine‐3,11(4H,12H)‐dione are prepared. The electrodes reveal a Nernstian behavior over wide Cu2+ ion concentration ranges (1.0×10?7–1.0×10?1 M for PME and 1.0×10?8–1.0×10?1 M for CGE) with very low limits of detection (7.8×10?8 M for PME and 9.1×10?9 M for CGE). The potentiometric responses are independent of the pH of the test solutions in the pH range 2.7–6.2. The proposed electrodes possess very good selectivities for Cu2+ over a wide variety of the cations including alkali, alkaline earth, transitions and heavy metal ions. The practical utility of the proposed electrodes have been demonstrated by their use in the study of interactions between copper ions and human growth hormone (hGH) in biological systems, potentiometric titration of copper with EDTA and determination of copper content of a sheep blood serum sample and some other real samples. 相似文献
5.
Mohammad Mazloum-Ardakani Mohammad Kazem Amini Marzieh Dehghan Elham Kordi Mohammad Ali Sheikh-Mohseni 《Journal of the Iranian Chemical Society》2014,11(1):257-262
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. 相似文献
6.
The electrochemical behaviour of dacarbazine [5-(3,3-dimethyl-1-triazenyl) imidazole-4-carboxamide; DTIC] was investigated by Tast and differential pulse polarography (d.p.p.) at the dropping mercury electrode, by cyclic and differential pulse voltammetry at the hanging mercury drop electrode and by anodic voltammetry at the glassy carbon electrode. Calibration graphs were obtained for 2×10?8?2×10?5 M DTIC by d.p.p., for 5×10?9?1×10?5 M by adsorptive stripping voltammetry ar a hanging mercury drop electrode, and for 1?10×10?5 M by high-performance liquid chromatography with oxidative amperometric detection at a glassy carbon electrode. The methods are compared and applied to determine DTIC added to blood serum after a simple clean-up procedure. 相似文献
7.
Electrode Based on Nickel‐containing SBA‐15 for the Determination of Copper in Ethanol Biofuel
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Sakae Y. Neto Helmara D. C. Viégas Joseany M. S. Almeida Eder T. G. Cavalheiro Antonio S. Araújo Edmar P. Marques Aldaléa L. B. Marques 《Electroanalysis》2016,28(5):1035-1043
A sensor based in a graphite–polyurethane composite electrode modified with the mesoporous nanostructured silica with hexagonal array of pores called Santa Barbara Amorphous type material (SBA‐15) containing nickel was built. The presence of Ni, incorporated during the synthesis of SBA‐15, resulted in an increase in sensitivity when compared to the other electrodes based on the unmodified SBA‐15. A procedure was proposed for the determination of Cu2+ in ethanol biofuel by square wave stripping voltammetry with linear response in concentration levels of 1.0×10?8 and 1.0×10?7 mol L?1, resulting in a limit of detection of 1.83×10?10 mol L?1 and precision (RSD) of 2.09 %. 相似文献
8.
Cathodic adsorptive stripping voltammetry (CASV) was applied for the determination of rutin in pharmaceuticals, human urine,
and blood serum. An electrochemical stripping procedure for trace measurements of rutin was developed based on the adsorption
of the Cu2+-rutin complex on a hanging mercury drop electrode and applied to the quantification of the drug. Cyclic voltammetry was used
to characterize the interfacial and redox behavior of the adsorbed Cu2+-rutin complex. Experimental and instrumental parameters for quantitative determination were optimized, and a detection limit
of 4.9 × 10−9 mol · L−1 in presence of Cu2+-ions for quantification of rutin under optimum conditions was derived. The sharp peak of the adsorbed Cu2+-rutin complex associated with an effective interfacial accumulation of this compound facilitates the determination of rutin
in biological fluids with good recoveries. The degree of interference from potentially present metal ions and organic compounds
on the CASV signal for Cu2+-rutin complex was evaluated. 相似文献
9.
《Analytical letters》2012,45(15):2835-2847
Abstract A sensitive voltammetric method for the determination of trace boron, based on the formation of the complex of boric acid with 4‐hydroxy‐5‐[salicylideneamino]‐2‐7‐naphthalenedisulfonic acid (azomethine H) is described. The reduction of the boric acid‐azomethine H complex at a hanging mercury drop electrode was exploited by square wave voltammetry (SWV) and cyclic voltammetry to determine boron in natural water samples, which were collected in the regions surrounding the boron mines of Central Anatolia. A reduction peak that belongs to the boric acid‐azomethine H complex at this electrode was observed at ?1.05 V vs. Ag/AgCl/KCl(sat.). The effects of various parameters, such as ligand concentration, boric acid concentration, and formation time of the boric acid‐azomethine H complex, were investigated. Electrochemical experiments were conducted in 1.0 M HOAc/0.5 M NH4OAc buffer at pH of 4.4±0.2. Linear working range was established by regression analysis between 5.0×10?8 M and 1.0×10?4 M. The probable metal cation interferences in water samples were eliminated by adding EDTA (ethylenediaminetetraacetic acid) to the samples. Data obtained using the square wave voltammetric (SWV) technique was compared statistically with inductively coupled plasma mass spectroscopy (ICP‐MS) data. Evaluation of the method based on statistical data was performed and the values of the limit of detection (LOD) and limit of quantitation (LOQ) were found to be 4.17×10?6 M and 1.39×10?5 M, respectively. 相似文献
10.
《Electroanalysis》2006,18(12):1193-1201
A chemically modified carbon paste electrode with 2,7‐bis(ferrocenyl ethyl)fluoren‐9‐one (2,7‐BFEFMCPE) was employed to study the electrocatalytic oxidation of ascorbic acid in aqueous solution using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The diffusion coefficient (D=1.89×10?5 cm2 s?1), and the kinetic parameter such as the electron transfer coefficient, α (=0.42) of ascorbic acid oxidation at the surface of 2,7‐BFEFMCPE was determined using electrochemical approaches. It has been found that under an optimum condition (pH 7.00), the oxidation of ascorbic acid at the surface of such an electrode occurs at a potential about 300 mV less positive than that of an unmodified carbon paste electrode. The catalytic oxidation peak currents show a linear dependence on the ascorbic acid concentration and linear analytical curves were obtained in the ranges of 8.0×10?5 M–2.0×10?3 M and 3.1×10?5 M–3.3×10?3 M of ascorbic acid with correlation coefficients of 0.9980 and 0.9976 in cyclic voltammetry and differential pulse voltammetry, respectively. The detection limits (2δ) were determined to be 2.9×10?5 M and 9.0×10?6 M with cyclic voltammetry and differential pulse voltammetry, respectively. This method was also examined for determination of ascorbic acid in pharmaceutical preparations. 相似文献
11.
B. B. Petković S. P. Sovilj M. V. Budimir R. M. Simonović V. M. Jovanović 《Electroanalysis》2010,22(16):1894-1900
The simple PVC‐based membrane containing N,N′,N″,N′′′‐tetrakis(2‐pyridylmethyl)‐1,4,8,11‐tetraazacyclotetradecane (tpmc) as an ionophore and dibutyl phthalate as a plasticizer, directly coated on a glassy carbon electrode was examined as a new sensor for Cu2+ ions. The potential response was linear within the concentration range of 1.0×10?1–1.0×10?6 M with a Nernstian slope of 28.8 mV/decade and detection limit of 7.0×10?7 M. The electrode was used in aqueous solutions over a wide pH range (1.3–6). The sensor exhibited excellent selectivity for Cu2+ ion over a number of cations and was successfully used in its determination in real samples. 相似文献
12.
Determination of Esomeprazole on an Electropolymerized L‐arginine and β‐cyclodextrin Modified Screen Printed Carbon Electrode
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The formation of an inclusion complex of the proton‐pump inhibitor (PPI) drug esomeprazole (ESO) with ß‐cyclodextrin (ß‐CD) has been investigated and proven by cyclic voltammetry (CV). The formation constant of the complex was determined. Thereafter, an electropolymerized β‐CD and L‐arginine (L‐arg) modified screen printed carbon electrode (P‐β‐CD‐L‐arg/SPCE) was developed for the determination of ESO using differential pulse adsorptive stripping voltammetry (DPAdSV). A significant enhancement of the peak current was observed when applying an accumulation step due to the effect of adsorption. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) further indicated that the polymer of β‐CD and L‐arg efficiently improved the electron transfer kinetic between analyte and electrode surface. Under the optimized conditions, the oxidation peak current was linearly proportional to the concentration of the drug in the range of 1.0×10?8 to 1.0×10?5 M. The DPAdSV method was successfully used to determine the concentrations of the drug in spiked human serum samples. 相似文献
13.
Application of 2‐(benzyliminomethyl)‐6‐methoxy‐4‐(4‐methoxyphenyl‐azo)phenol in construction of ion‐selective PVC membrane electrode for determination of copper (II) in mineral water sample
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The potentiometric characteristics of a new Cu2+‐selective electrode based on 2‐(benzyliminomethyl)‐6‐methoxy‐4‐(4‐methoxyphenyl‐azo) phenol as an efficient ionophore has been evaluated. The effects of influential parameters on the potentiometric responses such as the amount of plasticizer, the amount of ionophore, pH of the sample solution, and the effect of coexisting ions on the electrode signal were subsequently investigated . The selectivity of the electrode was assessed by calculating the selectivity coefficients using the matched potential method. The optimum ratio of the amount of materials required for the preparation of the electrode was found to be 1.7: 32.1: 64.2: 2.0 corresponding to carboxylated PVC, dimethyl sebacate as solvent mediators, potassium tetrakis (p‐chlorophenyl) borate as the anion localizing agent, and ionophore, respectively. The electrode had a fast response (7s) as well as a satisfactory Nernstian slope (29.26±0.91 mV/decade) to Cu2+ over a wide concentration range of 2.0×10?6‐ 5.0×10?2 M with a low detection limit of 5.9×10?7 M. The developed sensor was successfully used for the potentiometric titration of Cu2+ ion with EDTA and subsequently, efficient determination of this metal ion in a mineral water sample was performed. 相似文献
14.
Ana Paula Pires Eisele Débora Nóbile Clausen César Ricardo Teixeira Tarley Luiz Henrique Dall'Antonia Elen Romão Sartori 《Electroanalysis》2013,25(7):1734-1741
An electroanalytical method for the simultaneous determination of paracetamol (PAR), caffeine (CAF), and orphenadrine (ORPH) using the square‐wave voltammetry (SWV) and a cathodically pretreated boron‐doped diamond electrode was developed. The method exhibits linear responses to PAR, CAF, and ORPH in the concentration ranges 5.4×10?7–6.1×10?5 M, 7.8×10?7–3.5×10?5 M, and 7.8×10?7–3.5×10?5 M, respectively, with detection limits of 2.3×10?7 M, 9.6×10?8 M, and 8.4×10?8 M, respectively. The proposed method was successfully applied in the simultaneous determination of these analytes in pharmaceutical formulations. 相似文献
15.
Determination of Trichloroacetic Acid (TCAA) Using CdO Nanoparticles Modified Carbon Paste Electrode
In this paper, the electrochemical behavior of a carbon paste electrode modified with CdO nanoparticles as a potential electrocatalyst for the reduction of trichloroacetic acid (TCAA) was investigated using cyclic voltammetry and double‐potential step chronoamperometry. The modified electrode showed a great enhancement in cathodic peak current with respect to reduction of TCAA in acidic aqueous solution. Using this increment, a quantitative method was developed for the determination of TCAA in aqueous solution. The detection limit and linear dynamic range of TCAA are 2.3×10?6 M and 2.3×10?4–3×10?6 M, respectively. 相似文献
16.
An electroactive metal cyanometallate complex, nickel aquapentacyanoferrate (NAPCF) was synthesized and characterized using XRD and UV‐vis spectral studies. The solid complex was then mechanically immobilized on the surface of a paraffin impregnated graphite electrode (PIGE) and the NAPCF modified electrode was characterized using cyclic voltammetry. The dependence of the modified electrode was tested in terms of supporting electrolyte, scan rate and pH of the medium. The electrocatalytic oxidation of sulfite at the modified electrode was investigated by cyclic voltammetry, hydrodynamic voltammetry and chronoamperometry techniques. It was found that the NAPCF modified electrode efficiently exhibited electrocatalytic activity for the oxidation of sulfite with relatively high sensitivity, selectivity and long life of activity. Based on the electrocatalytic oxidation, the NAPCF modified electrode was used as a sensor for the determination of sulfite. The linear working range for the determination of sulfite was 2.78×10?6 M to 3.00×10?3 M with a detection limit of 9.26×10?7 M. The electrode was applied for the determination of sulfite in real samples satisfactorily. 相似文献
17.
《Analytical letters》2012,45(16):2436-2444
The work demonstrates a simple method for sensitive detection of Ca2+ ion by electrochemical response of alizarin red S (ARS) and Ca-ARS at a gold nanoparticle modified glassy carbon electrode (GCE). In the 0.1 M KOH, a sensitive reduction peak was observed at ?0.795 V at the gold nanoparticles modified electrode. The peak currents were proportional to the concentrations of Ca2+ ion in the range of 2.0 × 10?7 M–1.2 × 10?4 M. For the different pulse voltammetry (DPV) methods, the detection limit was 2.57 × 10?8 M. The reaction mechanism was primarily determined by cyclic voltammetry, and the experimental results showed that the electrode processes were quasireversible responses of ARS and irreversible responses of ARS-Ca. In addition, the method was simple, fast, precise, and was used in the determination of calcium in blood serum with satisfactory results. 相似文献
18.
《Electroanalysis》2003,15(20):1632-1638
The glutathione (GSH) self‐assembled monolayer and its compexlation with Cu2+ were studied by using voltammetry and EQCM. It was found that the monolayer could rearrange during the redox process of Cu2+/Cu+. The protonating, or not, of the carboxyl terminates of the adsorpted GSH molecules influence the compexlation interaction significantly for they are the key binding sites. The GSH monolayer had the capacity to accumulate Cu2+ and the monolayer modified gold electrode was employed to detect the low levels of Cu2+ with a limit of 1.0×10?10 mol L?1. 相似文献
19.
《Electroanalysis》2006,18(3):282-290
Metallophthalocyanine (MPc) and its derivatives are well known as electrocatalysts to catalyze oxidation or reduction of some species, such as cysteine, nitric oxide. Their nanosized particles may display the potential optics, electronic, catalytic and structural properties. In this paper, carbon paste electrodes modified with nanosized cobalt phthalocyanine particles (denoted as Nano‐CoPc‐CPE) are fabricated. The electrocatalytic oxidation of dopamine (DA) and ascorbic acid (AA) on the Nano‐CoPc‐CPE was investigated by means of cyclic voltammetry. Nano‐CoPc particles perform good electrocatalytic activity to DA and AA. The anodic peak potentials of DA and AA were separated with good sensitivity in the presence of cetyltrimethylammonium bromide (CTAB). The DA and AA can be simultaneously determined by using differential pulse voltammetry. On optimal conditions, the good linear response to DA and AA was observed in the range of 3.0×10?6–1.0×10?4 M and 5.0×10?6–3.0×10?4 M with the correlation coefficient of 0.9983 and 0.9978, respectively. Moreover, 100‐fold AA did not interfere in the determination of DA. This method has been used to simultaneously determine DA and AA concentration in mixed drug samples with satisfactory results. 相似文献
20.
Copper hexacyanoferrate (CuHCF) film‐modified carbon paste electrode (CPE) has been prepared from various electrolytic aqueous solutions using consecutive cyclic voltammetry. The cyclic voltammograms showed the direct deposition of CuHCF films from the mixing of Cu2+ and Fe(CN)63? ions and each time with one of the six cations: H+, Na+, K+, NH4+, Mg2+, and Al3+. The CuHCF film showed a single redox couple that exhibited a cation effect (Na+, K+, Mg2+, and NH4+) and anion effect (Cl?, NO3?, SO42?, ClO4?, and BrO3?) in the cyclic voltammograms. Voltammetric studies have indicated that in presence of nitrite, the cathodic peak current of CuHCF increases, followed by a decrease in the corresponding anodic current. This indicated that nitrite was reduced by the redox mediator immobilized on the electrode surface via an electrocatalytic mechanism. The process of reduction and its kinetics were investigated by using cyclic voltammetry, differential pulse voltammetry, chronoamperometry and chronocoulometry techniques. The electrocatalytic ability about 800 mV can be seen. The rate constant of the catalytic reduction of nitrite was found to be 7.9×105 cm3 mol?1 s?1. Linearity range obtained was 5×10?5?8.4×10?3 by cyclic voltammetry and 8×10?6?1.3×10?3 and 4×10?3?2×10?2 by differential pulse voltammetry. 相似文献