Preparation of silver hexacyanoferrate nanoparticles and its application for the simultaneous determination of ascorbic acid, dopamine and uric acid

A silver hexacyanoferrate nanoparticles/carbon nanotubes modified glassy carbon electrode was fabricated and then successfully used for the simultaneous determination of ascorbic acid, dopamine and uric acid by cyclic voltammetry. A detailed investigation by transmission electron microscopy (TEM) and electrochemistry was performed in order to elucidate the preparation process and properties of the nanocomposites. The size of silver hexacyanoferrate nanoparticles was examined by TEM around 27 nm. Linear calibration plots were obtained over the range of 4.0 × 10⁻⁶-7.8 × 10⁻⁵, 2.4 × 10⁻⁶-1.3 × 10⁻⁴ and 2.0 × 10⁻⁶-1.5 × 10⁻⁴ mol L⁻¹ with detection limits of 4.2 × 10⁻⁷,1.4 × 10⁻⁷ and 6.0 × 10⁻⁸ mol L⁻¹ for ascorbic acid, dopamine and uric acid, respectively. The practical analytical utilities of the modified electrode were demonstrated by the determination of ascorbic acid, dopamine and uric acid in urine and human blood serum samples.     

Ytterbium fluoride nanoparticles on carbon nanotubes: preparation, characterization and application for simultaneous electrochemical determination of ascorbic acid, dopamine and uric acid

A novel modified glassy carbon electrode with ytterbium fluoride nanoparticles (YFNPs)-multiwalled carbon nanotubes (MWCNTs) was fabricated and then successfully used for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). YFNPs were successfully coated on the MWCNTs via the intermediate of noncovalent hydrophobic interactions of the MWCNTs surface with sodium dodecyl sulfate. The YFNPs and immobilization of YFNPs on MWCNTs were confirmed by transmission electron microscopy. The particle size of YFNPs was measured to be around 45 nm. The catalytic peak currents for AA, DA and UA were linearly dependent on their concentrations in the range of 2.0–600.0, 2.0–560.0 and 1.8–640.0 μM, respectively, with the corresponding detection limits of 0.77, 0.22 and 0.17 μM. The modified electrode provided good sensitivity and stability, and was successfully applied for the simultaneous determination of AA, DA and UA in human blood serum and urine samples.     

基于纳米结构的电化学传感器用于伏安法测定苄丝肼、尿酸和叶酸(英文)

A carbon paste electrode modified with carbon nanotubes and ferrocene was fabricated.An electrochemical study of the modified electrode and an investigation into its efficiency for the electrocatalytic oxidation of benserazide,uric acid and folic acid were undertaken.The electrode was also used to study the electrocatalytic oxidation of benserazide using cyclic voltammetry,chronoamperometry,and square wave voltammetry(SWV).We found that the oxidation of benserazide at the surface of the modified electrode occurs at a potential about 285 mV lower than that of unmodified carbon paste electrode.SWV gave a linear dynamic range from 8.0×10-7 to 7.0×10 4 mol/L.The detection limit was 1.0×10-7 mol/L for benserazide.This modified electrode was used for the determination of benserazide,uric acid,and folic acid in an urine sample.     

Individual and simultaneous voltammetric determination of ascorbic acid,uric acid and folic acid by using a glassy carbon electrode modified with gold nanoparticles linked to bentonite via cysteine groups

A voltammetric sensor for both the individual and the simultaneous determination of ascorbic acid (AA), uric acid (UA) and folic acid (FA) is described. It is based on a glassy carbon electrode (GCE) that was modified with bentonite (Bnt) that was first functionalized with cysteine (Cys) to which gold nanoparticles were linked. The resulting material (referred to as Au-Cys-Bnt) and the other materials were characterized by UV-vis spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis and electrochemical methods. The XRD peak positions of bentonite and Cys-functionalized bentonite prove the incorporation of Cys into bentonite. The XPS spectrum of Au-Cys-Bnt confirms the interaction of gold nanoparticles with the thiol group of Cys. The modified GCE displays high electrocatalytic activity for the oxidation of AA, UA and FA, typically at 0.19, 0.41, and 0.73 V (vs. SCE), respectively. Differential pulse voltammetric data show a linear response that covers the 1 μM to 25 mM concentration range for AA, the 1 to 200 μM concentration range for UA, and two linear ranges for FA, one from 5 to 100 μM and one from 100 μM to 1.5 mM. The sensor was applied to the determination of AA, UA and FA in (spiked) multi-vitamin syrup, bird serum and milk samples.

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Graphical abstract Schematic of a sensor for simultaneous and individual electrochemical determination of ascorbic, uric, and folic acids in real samples. The sensor consists of a glassy carbon electrode that was modified with a nanocomposite prepared from bentonite that was first functionalized with cysteine to which gold nanoparticles were linked.

     

Cu nanoparticles incorporated polypyrrole modified GCE for sensitive simultaneous determination of dopamine and uric acid

Cu nanoparticles have been electrochemically incorporated polypyrrole film that was used for modification of the glassy carbon electrode surface. The performance of the electrode has been characterized by cyclic voltammetry and atomic force microscopy. The electrode has shown high electrocatalytic activity towards the oxidation of dopamine (DA) and uric acid (UA) simultaneously in a phosphate buffer solution (pH 7.00). The electrocatalytic oxidation currents of UA and DA were found linearly related to concentration over the range 1 × 10⁻⁹ to 1 × 10⁻⁵ M for UA and 1 × 10⁻⁹ to 1 × 10⁻⁷ M for DA using DPVs method. The detection limits were determined as 8 × 10⁻¹⁰ M (s/n = 3) for UA and 8.5 × 10⁻¹⁰ M (s/n = 3) for DA at a signal-to-noise ratio of 3.     

Simultaneous determination of dopamine, uric acid and ascorbic acid with LaFeO3 nanoparticles modified electrode

LaFeO₃ nanoparticles of approximately 22 nm in size were synthesized and characterized by XRD and TEM. A novel glassy carbon electrode modified with LaFeO₃ nanoparticles was constructed and characterized by electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode exhibited strong promoting effect and high stability toward the electrochemical oxidation of dopamine (DA), which gave reversible redox peaks with a formal potential of 0.145 V (vs. Ag/AgCl) in pH 7.0 phosphate buffer solution. The anodic peak current (measured by constant potential amperometry) increased linearly with the concentration of dopamine in the range from 1.5?×?10^?7 to 8.0?×?10^?4 M. The detection limit was 3.0?×?10^?8 M. The relative standard deviation of eight successive scans was 3.47% for 1.0?×?10^?6 M DA. The interference by ascorbic acid was eliminated efficiently. The method was used to determine DA in dopamine hydrochloride injections and showed excellent sensitivity and recovery.     

Electroanalysis and simultaneous determination of 6-thioguanine in the presence of uric acid and folic acid using a modified carbon nanotube paste electrode

The present work describes the preparation and characterization of a carbon nanotube paste electrode modified with 2,7-bis(ferrocenyl ethyl)fluoren-9-one (2,7-BF). This electrode showed an efficient catalytic activity for the electro-oxidation of 6-thioguanine (6-TG), which leads to lowering 6-TG overpotential by more than 610 mV. Also, the values of catalytic rate constant (k = 2.7 × 10(3) mol(-1) L s(-1)), and diffusion coefficient (D = 2.7 × 10(-5) cm(2) s) were calculated. In 0.1 M phosphate buffer solution of pH 7.0, the oxidation current increased linearly with two concentration intervals of 6-TG, one is 0.06 to 10.0 μmol L(-1) and the other is 10.0 to 160.0 μmol L(-1). The detection limit (3σ) obtained by differential pulse voltammetry (DPV) was 22.0 nmol L(-1). DPV was used for simultaneous determination of 6-TG, uric acid (UA) and folic acid (FA) at the modified electrode, and for quantification of 6-TG, UA and FA in some real samples by the standard addition method.     

One-pot synthesis of ternary hybrid nanomaterial composed of a porphyrin-functionalized graphene,tin oxide,and gold nanoparticles,and its application to the simultaneous determination of epinephrine and uric acid

Microchimica Acta - We reported on the one-pot synthesis of a ternary hybrid material composed of graphene functionalized with 5,10,15,20-tetrakis (4-sulfonatophenyl) porphyrin, tin oxide, and gold...     

Electrochemical sensing and simultaneous determination of ascorbic acid,dopamine and uric acid at nickel nanoparticles/poly (1,2-diaminoanthraquinone) modified electrode

A highly sensitive sensor based on Ni nanoparticles/poly (1,2-diaminoanthraquinone) modified electrode was fabricated at glassy carbon (GC) electrode (Ni/PDAAQ@GC ME) using cyclic voltammetry technique. The incorporation of nickel (II) ions nanoparticles (Ni NPs) followed by anodic polarization process was achieved. Surface morphologies of both PDAAQ@GC ME and Ni/PDAAQ@GC MEs were studied by scanning electron microscope. Ni/PDAAQ@GC ME was tested for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) by square wave voltammetry technique. The ME showed excellent electrocatalytic activity toward electrooxidation of these biomolecules in their single, binary and ternary systems in alkaline 0.1 M NaOH solutions. Experiment revealed that the low detection limits (LOD) for AA, DA and UA were 0.11, 0.072 and 1.2 µM in single system, respectively, and 0.069, 0.29 and 0.12 µM in ternary system, respectively.     

基于纳米结构的电化学传感器同时测定溶液中异丙肾上腺素、尿酸和叶酸的浓度(英文)

A carbon paste electrode modified with 2‐((7‐(2,5-dihydrobenzylideneamino)heptylimino)methyl) benzene‐1,4‐diol(DHB) and carbon nanotubes were used to simultaneously determine the concen-trations of isoproterenol(IP), uric acid(UA), and folic acid(FA) in solution. First, cyclic voltammetry was used to investigate the redox properties of the modified electrode at various scan rates. Next, the mediated oxidation of IP at the modified electrode is described. At the optimum pH of 7.0, the oxidation of IP occurs at a potential about 90 mV less than that of an unmodified carbon paste elec-trode. Based on the results of differential pulse voltammetry(DPV), the oxidation of IP showed a dynamic range between 10 and 6000 μmol/L, and a detection limit of 1.24 μmol/L. Finally, DPV was used to simultaneously determine the concentrations of IP, UA, and FA in solution at the modified electrode.     

Ultra-sensitive voltammetric simultaneous determination of dopamine,uric acid and ascorbic acid based on a graphene-coated alumina electrode

The authors describe the fabrication of an interconnected edge-exposed graphene nanostructure via chemical vapor deposition (CVD) of foliated graphene onto a network of alumina nanofibers. The fibers such obtained are shown to enable ultra-sensitive voltammetric determination of dopamine (DA), uric acid (UA) and ascorbic acid (AA). The electrode displays powerful and persistent electro oxidative behavior and excellent electron transport properties. Cyclic voltammetry and differential pulse voltammetry demonstrate excellent selectively and sensitivity for AA, DA and UA, with typical peaks at ?0.08 V, +0.19 V, and +0.34 V (vs. SCE), respectively. Under optimum conditions, the calibration plots are linear in the 1–80 μM range for DA, in the 1–60 μM range for UA, and in the 0.5–60 μM range for UA, with detection limits of 0.47 μM, 0.28 μM and 0.59 μM, respectively. The sensor was successfully applied to the simultaneous determination of DA and UA in the presence of AA in spiked urine sample.

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Graphical abstract Material with high density of graphene foliates grown over highly aligned nano-dimensional ceramic fibers is used as electrode for simultaneous highly sensitive electrochemical determination of DA in the presence of UA and AA with a considerably low limit of detection.

     

Individual and simultaneous determination of uric acid and ascorbic acid by flow injection analysis

Flow injection methods for the individual and simultaneous determination of ascorbic acid and uric acid are proposed. A spectrophotometer and a miniamperometric detector are connected in sequence. The calibration graphs for uric acid obtained by measuring its absorbance at 293 nm and its current at +0.6 V are linear up to at least 80 and 70 mug/ml, respectively, with an rsd (n = 10) of 1 % for both methods at mid-range concentrations. The calibration graph for ascorbic acid with amperometric detection is linear up to 80 mg/l. with an rsd (n = 10) of 0.8% at 30 mg/l. The simultaneous determination of uric acid and ascorbic acid is based on measurement of the absorbance of uric acid at 393 nm and amperometric determination of both analytes at +0.6 V. The average relative errors of the analysis of binary mixtures of uric acid and ascorbic acid are 2.2 and 4.2%, respectively.     

Solvent dependent dimercaptothiadiazole monolayers on gold electrode for the simultaneous determination of uric acid and ascorbic acid

Dimercaptothiadiazole compound, 2,5-dimercapto-1,3,4-thiadiazole (DMcT) forms ‘thin’ monolayers on Au electrode when it was adsorbed from methanol, ethanol or DMSO solutions while it forms ‘thick’ layers on Au electrode from an aqueous solution under identical experimental conditions. Thick DMcT layers formed from aqueous solution effectively blocks the redox reaction of couple in contrast to thin DMcT monolayers. The monolayer thickness did not vary when structurally related DMcT compounds, 5-methyl-1,3,4-thiadiazole-2-thiol or 5-amino-1,3,4-thiadiazole-2-thiol was adsorbed from aqueous and non-aqueous solutions. This indicates that the presence of two thiol groups in DMcT plays a crucial role in the formation of thick and thin DMcT layers on Au electrode when it was adsorbed from aqueous and non-aqueous solutions. Methanol, ethanol, or DMSO solution of DMcT is considered as strong acid because these solvents are able to deprotonate DMcT into DMcT⁻ and thus thin monolayers formed on Au electrode. The deprotonating ability of these solvents was further verified from the observed absorption spectrum characteristic of DMcT⁻ species. On the other hand, an aqueous solution of DMcT is less acidic due to weak deprotonation of DMcT by water and thus DMcT forms thick layer on Au electrode. Interestingly, thin DMcT monolayers formed from non-aqueous solvents separates the voltammetric signals of uric acid and ascorbic acid while thick DMcT layers formed from aqueous solution fails to separate them.     

Amperometric sensor based on carbon nanotubes and electropolymerized vanillic acid for simultaneous determination of ascorbic acid,dopamine, and uric acid

This paper describes the development of a simple and efficient nanostructured platform based on multi-walled carbon nanotubes (MWCNT) functionalized with an in situ generated vanillic acid (VA) polymer. It was used as an analytical sensor for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). The electropolymerization process of VA, performed on MWCNT-modified glassy carbon electrode, produces three redox systems based on quinone/hydroquinone functionality, as observed by cyclic voltammetry. The amperometric sensor has as figures of merit for the simultaneous determination of AA, DA, and UA the following values: for AA, a linear range of 5–120 μM and detection limit of 3.5 μM; for DA, a linear range of 5–120 μM and detection limit of 4.5 μM; and for UA, a linear range of 5–120 μM and a detection limit of 1.5 μM. From the obtained performance, the development of the platform based on MWCNT/poly-VA is justified for the simultaneous determination of AA, DA, and UA.     

Facile low-temperature growth of carbon nanosheets toward simultaneous determination of dopamine, ascorbic acid and uric acid

The bare Pt electrode modified directly and simply by carbon nanosheets, which were synthesized by microwave plasma enhanced chemical vapor deposition at relatively low temperature, can be used to simultaneously and effectively detect dopamine, ascorbic acid and uric acid.     

Microfluidic paper-based chemiluminescence biosensor for simultaneous determination of glucose and uric acid

In this study, a novel microfluidic paper-based chemiluminescence analytical device (μPCAD) with a simultaneous, rapid, sensitive and quantitative response for glucose and uric acid was designed. This novel lab-on-paper biosensor is based on oxidase enzyme reactions (glucose oxidase and urate oxidase, respectively) and the chemiluminescence reaction between a rhodanine derivative and generated hydrogen peroxide in an acid medium. The possible chemiluminescence assay principle of this μPCAD is explained. We found that the simultaneous determination of glucose and uric acid could be achieved by differing the distances that the glucose and uric acid samples traveled. This lab-on-paper biosensor could provide reproducible results upon storage at 4 °C for at least 10 weeks. The application test of our μPCAD was then successfully performed with the simultaneous determination of glucose and uric acid in artificial urine. This study shows the successful integration of the μPCAD and the chemiluminescence method will be an easy-to-use, inexpensive, and portable alternative for point-of-care monitoring.     

Glassy carbon electrode modified with gold nanoparticles and DNA for the simultaneous determination of uric acid and norepinephrine under coexistence of ascorbic acid.

A novel biochemical sensor was assembled on a glass carbon electrode by a electrodeposition process. Gold nanoparticles were deposited by potential +1.5 V on the glass carbon electrode. CT-DNA was deposited by potential +1.5 V on the gold nanoparticles array electrode. The properties of the modified electrode were characterized by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Our results showed that gold nanoparticles increase the DNA membrane capacitance and reduce the membrane resistance. This modified electrode can selectively determine uric acid and norepinephrine in the presence of a larger amount of ascorbic acid. The fabricated electrode showed good sensitivity, reproducibility, and stability.     

Four-way calibration applied to the simultaneous determination of folic acid and methotrexate in urine samples

First-, second- and third-order calibration methods were investigated for the simultaneous determination of folic acid and methotrexate. The interest in the determination of these compounds is related to the fact that methotrexate inhibits the body’s absorption of folic acid and prolonged treatment with methotrexate may lead to folic acid deficiency, and to the use of folic acid to cope with toxic side effects of methotrexate. Both analytes were converted into highly fluorescent compounds by oxidation with potassium permanganate, and the kinetics of the reaction was continuously monitored by recording the kinetics curves of fluorescence emission, the evolution with time of the emission spectra and the excitation–emission matrices (EEMs) of the samples at different reaction times. Direct determination of mixtures of both drugs in urine was accomplished on the basis of the evolution of the kinetics of EEMs by fluorescence measurements and four-way parallel-factor analysis (PARAFAC) or multiway partial least squares (N-PLS) chemometric calibration. The core consistency diagnostic (CORCONDIA) was employed to determine the correct number of factors in PARAFAC and the procedure converged to a choice of three factors, attributed to folic acid, methotrexate and to the sum of fluorescent species present in the urine.      

Electropolymerized film of functionalized thiadiazole on glassy carbon electrode for the simultaneous determination of ascorbic acid, dopamine and uric acid

The present study reports the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in 0.20 M phosphate buffer solution (pH 5.0) using electropolymerized ultrathin film of 5-amino-2-mercapto-1,3,4-thiadiazole (AMT) on glassy carbon (GC) electrode. The bare GC electrode does not separate the voltammetric signals of AA, DA and UA. However, electropolymerized AMT (p-AMT) modified GC electrode not only resolved the voltammetric signals of AA, DA and UA but also dramatically enhanced their oxidation peak currents when compared to bare GC electrode. The enhanced oxidation currents for AA, DA and UA at p-AMT modified electrode are due to the electrostatic interactions between them and the polymer film. Using amperometric method, we achieved the lowest detection of 75 nM AA, 40 nM DA and 60 nM UA at p-AMT modified electrode. The amperometric current was linearly increased from 200 nM to 0.80 mM for each AA, DA and UA and the lowest detection limit was found to be 0.92, 0.07 and 0.57 nM, respectively (S/N = 3). The practical application of the modified electrode was demonstrated by the determination of DA in dopamine hydrochloride injection.