A simple and efficient electrochemical sensor for folic acid determination in human blood plasma based on gold nanoparticles–modified carbon paste electrode

Folic acid (FA) is a water soluble vitamin that exists in many natural species. The lack of FA causes some deficiencies in human body, so finding a simple and sensitive method for determining the FA is important. A new chemically modified electrode was fabricated for determination of FA in human blood plasma using gold nanoparticles (AuNPs) and carbon paste electrode (CPE). Gold nanoparticles–modified carbon paste electrode (AuNPs/CPE) was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The experimental parameters such as pH, scan rate (ν) and amount of modifier were studied by cyclic voltammetry and the optimized values were chosen. The electrochemical parameters such as diffusion coefficient of FA (D_FA), electrode surface area (A) and electron transfer coefficient (α) were calculated. Square wave voltammetry as an accurate technique was used for quantitative calculations. A good linear relation was observed between anodic peak current (i_pa) and FA concentration (C_FA) in the range of 6 × 10^? 8 to 8 × 10^? 5 mol L^? 1, and the detection limit (LOD) achieved 2.7 × 10^? 8 mol L^? 1, that is comparable with recently studies. This paper demonstrated a novel, simple, selective and rapid sensor for determining the FA in the biological samples.     

Electrogenerated chemiluminescence sensor for formaldehyde based on Ru(bpy)32+-doped silica nanoparticles modified Au electrode

A novel and sensitive electrogenerated chemiluminescence (ECL) sensor for formaldehyde was developed with the amine-functionalized Ru(bpy)₃²⁺-doped silica nanoparticles (Ru-DSNPs) as ECL emitter. Ru(bpy)₃²⁺ doped on the silica nanoparticle can maintain its electrochemical activities, which made silica nano-beads a excellent carrier of Ru(bpy)₃²⁺ species. The uniform Ru-DSNPs (about 75 nm) were conjugated with Au electrode using mercaptoacetic acid as the intermediate to fabricate an ECL sensor for formaldehyde. The ECL analytical performances of this ECL sensor for formaldehyde based on its enhancement ECL emission of Ru(bpy)₃²⁺ were investigated in details. Under the optimum condition, the ECL intensity was linear with the formaldehyde concentration in the range of 1.0 × 10^? 8 mol/L to 1.0 × 10^? 6 mol/L. The detection limit was 6.0 × 10^? 9 mol/L (S/N = 3). This approach offered obvious advantages of being simpler, faster, and more stable compared with other sensors, and possessed great potential for formaldehyde detection which could be applied to determine directly the formaldehyde in real samples without pre-separation.     

Thermal conductivity and Kapitza resistance of cyanate ester epoxy mix and tri-functional epoxy electrical insulations at superfluid helium temperature

In the framework of the European Union FP7 project EuCARD, two composite insulation systems made of cyanate ester epoxy mix and tri-functional epoxy (TGPAP-DETDA) with S-glass fiber have been thermally tested as possible candidates to be the electrical insulation of 13 T Nb₃Sn high field magnets under development for this program. Since it is expected to be operated in pressurized superfluid helium at 1.9 K and 1 atm, the thermal conductivity and the Kapitza resistance are the most important input parameters for the thermal design of this type of magnet and have been determined in this study. For determining these thermal properties, three sheets of each material with different thicknesses varying from 245 to 598 μm have been tested in steady-state condition in the temperature range of 1.6–2.0 K. The thermal conductivity for the tri-functional epoxy (TGPAP-DETDA) epoxy resin insulation is found to be k = [(34.2 ± 5.5)?T ? (16.4 ± 8.2)] × 10^?3 Wm^?1 K^?1 and for the cyanate ester epoxy k = [(26.8 ± 4.8)?T ? (9.6 ± 5.2)] × 10^?3 Wm^?1 K^?1. For the Kapitza resistance, R_k, the best curve fitting the experimental data is described by R_k = (3057 ± 593) × 10^?6?T (?1.79 ± 0.34) m² KW^?1 for the TGPAP-DETDA insulation and R_k = (4114 ± 971) × 10^?6?T (?1.73 ± 0.41) m² KW^?1 for the cyanate ester epoxy insulation. Our results are compared with other epoxy based composite electrical insulation found in the literature.     

Development of a conductive composite based on polythiophene/Y-zeolite and its response towards sulfide ions

A new potentiometric sensor electrode for sulfide based on conducting polymer films is introduced. A composite of polythiophene (PTP) with Y-zeolite was prepared via chemical oxidative polymerization of thiophene (TP) in presence of a dispersion of Y-zeolite (powder) in CHCl3 solvent using anhydrous FeCl3 oxidant. Formation of polythiophene and its subsequent SEM and TEM analysis revealed formation of composite particles with average diameter in the range of 0.3–0.35 μm. DC conductivity value of the PTP-Y-zeolite composite was in the order of 10? 2 S/cm, which was indeed high compared to that of PTP, produced under identical conditions as above without the presence of Y-zeolite. This composite as active component with graphite powder and binding liquid was mixed and then used for preparation of solid state electrodes. The working temperature range for this electrode is between 20 and 40 °C. The linear dynamic range is 1 × 10? 7 – 1 × 10? 4 M and measures total sulfide concentration over a range of pH from 5 to 9. The composite electrode showed high selectivity for sulfide in the presence of many common interfering anions (? log KS, IO3?Pot = 6.3, ? log KS, BrO3?Pot = 5.5, ? log KS, S2O32 ?Pot = 4.8).     

Flux growth and thermal properties of LiBaB9O15 single crystal

A large LiBaB₉O₁₅ single crystal has been grown by the top-seeded solution growth (TSSG) method using a Li₂Mo₃O₁₀ flux system. The crystal obtained exhibits (1 1 0), (1 1 3) and (1 0 2) faces. For the first time, thermal properties of the as-grown crystal, including thermal expansion, specific heat and thermal conductivity, have been investigated as a function of temperature. The specific heat of the LiBaB₉O₁₅ crystal was measured to be 0.663–1.110 J g^?1 K^?1 over the temperature range of 20–400 °C. The crystal exhibits thermal expansion along the a- and b-axis, coupled with thermal contraction along the c-axis, over the measured temperature range of 25–500 °C. The average thermal expansion coefficients along the a- and c-axis of the LiBaB₉O₁₅ crystal from 25 to 500 °C are calculated to be α_a = 6.56 × 10^?6 K^?1 and α_c = ?4.82 × 10^?6 K^?1, respectively.     

An innovative process to fabricate copper/diamond composite films for thermal management applications

Diamond dispersed copper matrix (Cu/D) composite films with strong interfacial bonding were produced by tape casting and hot pressing without carbide forming additives. The tape casting process offers an original solution to obtain laminated materials with accurate thickness control, smooth surface finish, material net-shaping, scalability, and low cost. This study presents an innovative process of copper submicronic particles deposition onto diamond reinforcements prior to densification by hot pressing. Copper particles act as chemical bonding agents between the copper matrix and the diamond reinforcements during hot pressing, thus offering an alternative solution to traditionnal carbide-forming materials in order to get efficient interfacial bonding and heat-transfer in Cu/D composites. It allows high thermal performances with low content of diamond, thus enhancing the cost-effectiveness of the materials. Microstructural study of composites by scanning electron microscopy (SEM) was correlated with thermal conductivity and thermal expansion coefficient measurements. The as-fabricated films exhibit a thermal conductivity of 455 W m^?1 K^?1 associated to a coefficient of thermal expansion of 12 × 10^?6 °C^?1 and a density of 6.6 g cm^?3 with a diamond volume fraction of 40%, which represents a strong enhancement relative to pure copper properties (λ_Cu = 400 W m^?1 K^?1, α_Cu = 17 × 10^?6 °C^?1, ρ_Cu = 8.95 g cm^?3). The as-fabricated composite films might be useful as heat-spreading layers for thermal management of power electronic modules.     

A Ho(III) potentiometric polymeric membrane sensor based on a new four dentate neutral ion carrier

In this research, we report a new Ho^3 +-PVC membrane electrode based on N-(4,5-dimethyl-2-(picolinamido)phenyl)picolinamide (H₂Me₂bpb) as a suitable ion carrier. Poly vinylchloride (PVC)-based membrane composed of H₂Me₂bpb with oleic acid (OA) as anionic additives, and o-nitrophenyloctyl ether (NPOE) as plasticized solvent mediator. The sensor exhibits a Nernstian slope of 20.1 ± 0.2 mV decade^? 1 over the concentration range of 1.0 × 10^? 6 to 1.0 × 1^? 2 mol L^? 1, and a detection limit of 5.0 × 10^? 7 mol L^? 1 of Ho^3 + ions. The potentiometric response of the sensor is independent of the solution pH in the range of 3.5–9.4. It has a very short response time, in the whole concentration range (< 10 s), and can be used for at least eight weeks. The proposed electrode shows a good selectivity towards Ho^3 + ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. To assess its analytical applicability the proposed Ho^3 + sensor was successfully applied as an indicator electrode in the titration of Ho^3 + ion solutions in certified reference materials, alloy samples and for the determination of the fluoride ion in two mouthwash preparations.     

Simultaneous determination of phenylhydrazine and hydrazine by a nanostructured electrochemical sensor

In the present paper, the use of a nanostructured electrochemical sensor was described for simultaneous determination of phenylhydrazine (PhH) and hydrazine (HZ). This electrochemical sensor was prepared by a simple and rapid method by modification of carbon paste electrode with a derivative of hydroquinone and TiO₂ nanoparticles. The modified electrode showed an excellent character for electrocatalytic oxidation of PhH. Using differential pulse voltammetry, a highly selective and simultaneous determination of PhH and HZ has been explored at the modified electrode. Differential pulse voltammetry peak currents of PhH and HZ increased linearly with their concentration at the ranges of 2.0 × 10^? 6 to 1.0 × 10^? 3 M and 7.5 × 10^? 5–1.0 × 10^? 3 M, respectively and the detection limits for PhH and HZ were 7.5 × 10^? 7 M and 9.0 × 10^? 6 M, respectively.     

Neutral N,N′-bis(2-pyridinecarboxamide)-1,2-ethane as sensing material for determination of lutetium(III) ions in biological and environmental samples

The biological properties of the lutetium as well as other lanthanide ions, primarily based on their similarity to calcium, have been the bases for research into potential therapeutic applications of lanthanide series since the early part of the twentieth century. In this research, a Lu(III) potentiometric membrane sensor based on N,N′-bis(2-pyridinecarboxamide)-1,2-ethane (PCAE) is described. The sensor exhibits a Nernstian response over a concentration range of 1.0 × 10^? 6 mol L^? 1–1.0 × 10^? 1 mol L^? 1, with a detection limit of 6.0 × 10^? 7 mol L^? 1. The best performance was achieved with a membrane composition, consisting of 30% PVC, 63% o-nitrophenyl octyl ether (NPOE), 5% PCAE and 2% sodium tetraphenylborate (NaTPB). It was found that at the pH range of 4.0–9.0, the potential response of the sensor was not affected by the pH. Furthermore, the electrode presents satisfactory reproducibility, very fast response time (5 s) and relatively good discriminating ability for Lu(III) ions with respect to many common cations and other lanthanide ions. The sensor has been applied to the determination of Lu(III) in human serum and in some soil samples where domestic devices were stored.     

Electrochemical oxidation of adenosine-5′-triphosphate on a chitosan–graphene composite modified carbon ionic liquid electrode and its determination

In this paper a new electrochemical method was proposed for the determination of adenosine-5′-triphosphate (ATP) based on a chitosan (CTS) and graphene (GR) composite film modified carbon ionic liquid electrode (CTS–GR/CILE). CILE was fabricated by using ionic liquid 1-butyl-3-methylimidazolium dihydrogen phosphate ([BMIM]H₂PO₄) as the binder, which was further modified by GR and CTS composite. The modified electrode exhibited an excellent electrocatalytic activity toward the oxidation of ATP with the increase of the oxidation peak current and the decrease of the oxidation peak potential. The electrochemical parameters of ATP on CTS–GR/CILE were calculated with the electron transfer coefficient (α) as 0.329, the electron transfer number (n) as 2.15, the apparent heterogeneous electron transfer rate constant (ks) as 3.705 × 10^? 5 s^? 1 and the surface coverage (Γ_T) as 9.33 × 10^? 10 mol cm^? 2. Under the optimal conditions the oxidation peak current was proportional to ATP concentration in the range from 1.0 × 10^? 6 to 1.0 × 10^? 3 M with the detection limit of 0.311 μM (S/N = 3). The proposed electrode showed excellent reproducibility, stability, anti-interference ability and further successfully applied to the ATP injection sample detection.     

Application of 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea as sensing material for construction of Tm3+-PVC membrane sensor

A thulium(III) membrane sensor was made using 2% sodium tetraphenyl borate (NaTPB), 65% dibutylphthalate (DBP), 30% poly(vinyl chloride) (PVC) and 3% 1-ethyl-3-(2,5-dihydro-4-(3,5-dimethyl-1H-pyrazol-4-yl)-5-oxo-1H-pyrazol-3-yl)thiourea (ET) as an ionophore. Conductometric study shows selectivity of the Et toward Tm³⁺ ions. Nernstian response of 19.6 ± 0.4 mV per decade of thulium concentration was observed, and the electrode worked well in concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with a lower detection limit (LDL) of 7.2 × 10^? 7 mol L^? 1, in a pH range of 4.3–10.4. The selectivity of the sensor over alkaline, alkaline earth, transition and heavy metal ions was also found to be in a satisfactory range. To check the analytical applicability of the proposed Tm³⁺ sensor, it was successfully used as an indicator electrode in analysis of thulium in certified reference materials.     

EPR and optical absorption studies of Cr3+ doped lithium potassium sulphate single crystals

X-band electron paramagnetic resonance (EPR) studies of Cr³⁺ doped lithium potassium sulphate single crystals have been done at room temperature. The Cr³⁺ crystal field and spin Hamiltonian parameters have been evaluated by employing resonance line positions observed in the EPR spectra for different orientations of external magnetic field. The evaluated g, D and E values are: g_x = 2.0763 ± 0.0002, g_y = 1.9878 ± 0.0002, g_z = 1.8685 ± 0.0002 and D = 549 ± 2 × 10^?4 cm^?1, E = 183 ± 2 × 10^?4 cm^?1. Using EPR data the site symmetry of Cr³⁺ ion in the crystal is discussed. Cr³⁺ ion enters the lattice substitutionally replacing K⁺ site. The optical absorption study of the single crystal is also done in 195–925 nm wavelength range at room temperature. By correlating optical and EPR data the nature of bonding in the crystal is discussed. The calculated values of Racah parameters (B and C), crystal field parameter (D_q) and nephelauxetic parameters (h and k) are obtained as: B = 697, C = 3247, D_q = 2050 cm^?1, h = 1.146 and k = 0.21.     

Effect of electron irradiation on characteristics of Mo Schottky barriers on epitaxial silicon

The results of studies on influence of 6 MeV electron irradiation on avalanche breakdown voltage (U_b) and on forward voltage (U_F) at different values of direct current (I_F) for the Mo Schottky diodes on epitaxial silicon of n-type conductivity are presented. It was found out that the avalanche breakdown voltage of the diodes is very sensitive to electron irradiation. A decrease in U_b was observed after electron irradiation with a fluence as low as 1 × 10¹¹ cm^?2. An increase in electron irradiation fluence from 1 × 10¹¹ cm^?2 to 5 × 10¹⁴ cm^?2 resulted in 30% decrease in U_b, however, further increase in electron irradiation fluence from 5 × 10¹⁴ cm^?2 to 3 × 10¹⁶ cm^?2 led to some increase in the avalanche breakdown voltage. Monotonic increases in U_F values at different I_F with the increase in electron irradiation fluence were observed starting from a fluence of 5 × 10¹⁴ cm^?2. Radiation-induced changes in U_b were unstable at room temperature and a significant recovery of U_b occurred after maintaining the irradiated diodes at room temperature for 30 days. Annealing at 120 °C for 20 min resulted in the almost complete recovery of U_b. Radiation-induced changes in U_F values were stable up to 300 °C. Mechanisms of the observed radiation-induced changes in the U_b and U_F values and defects responsible for the changes are discussed.     

Biopolymer-manganese oxide nanoflake nanocomposite films fabricated by electrostatic layer-by-layer assembly

Bio-nanocomposite films based on chitosan and manganese oxide nanoflake have been fabricated via the layer-by-layer (LBL) self-assembly technique. UV–vis absorption spectra showed that the subsequent growth of the nanocomposite film was regular and highly reproducible from layer to layer. X-ray photoelectron spectroscopy (XPS) spectra confirmed the incorporation of chitosan and manganese oxide nanoflake into the films. Scanning electron microscopy (SEM) images revealed that the nanocomposite film had a continuous surface and a layered structure. A sensitive hydrogen peroxide (H₂O₂) amperometric sensor was fabricated with the chitosan–manganese oxide nanoflake nanocompoite film. The sensor showed a rapid and linear response to H₂O₂ over the range from 2.5 × 10^? 6 to 1.05 × 10^? 3 M, with a sensitivity of 0.038 A M^? 1 cm^? 2.     

Selective electrodes for [PF6]− and [BF4]− anions based on the associates formed by ionic liquid and cationic dyes

The feasibility of the newly synthesized ionic associates L1 and L2 formed by ionic liquid [C₄mim][PF₆] and cationic dyes (malachite green and methylene blue) has been tested as a novel ionophore for the preparation of anion-selective polymeric membrane electrodes. The electrode exhibits Nernstian response and enhanced potentiometric selectivity towards [PF₆]^? compared to many other anions. The influence of some experimental parameters such as membrane composition, nature of plasticizer and amount of additive on the potential response of the [PF₆]^? sensor are investigated. Under the optimized conditions, the response slopes of the membrane electrodes towards [PF₆]^? are 59.7 ± 0.5 and 58.1 ± 0.5 mV/decade based on ionophore L1 and L2, respectively, in 1.0 × 10^? 5–1.0 × 10^? 1 or 1.0 × 10^? 6–1.0 × 10^? 1 mol/L concentration range. Interestingly, the optimized electrodes based on ionophores L1 and L2 also exhibit Nernstian response characteristics (60.3 ± 0.5 and 56.0 ± 0.5 mV/decade) for tetrafluoroborate anion [BF₄]^? in a wide concentration range. Thus, the proposed sensor has been used for the determination of [PF₆]^? and [BF₄]^? in aqueous ionic liquids samples and the solubility of the [PF₆]^? and [BF₄]^? based ionic liquids in water. The satisfactory results are obtained.     

Praseodymium analysis in aqueous solution by Pr3+–PVC membrane sensor based on N,N′-bis(4-hydroxysalicylidene)-1-3-phenylenediamine

A new Pr³⁺ poly vinyl chloride PVC membrane sensor based on a membrane containing 3% N,N′-bis(4-hydroxysalicylidene)-1-3-phenylenediamine (HSPDA) as an ionophore, 2% sodium tetraphenyl borate (NaTPB) as an anionic additive, 65% benzyl acetate (BA) as solvent mediator and 30% poly(vinyl chloride) was prepared. This sensor responds to praseodymium ion in a wide linear dynamic range of 1.0 × 10^?6 to 1.0 × 10^?2 mol L^?1 with Nernstian slope of 19.8 ± 0.4 mV per decade and a detection limit of 5.7 × 10^?7 mol L^? 1 in pH range of 3.1 to 9.8. It has a fast response time of ~5 s in the whole concentration range, and can be used for at least 2 months without any considerable divergences in the potentials. The proposed sensor displays an excellent selectivity for Pr³⁺ ions with respect to a large number of alkali, alkaline earth, transition and heavy metal ions. The developed sensor was successfully applied as an indicator electrode in Pr³⁺ ion potentiometric titration with EDTA, and in direct determination of fluoride ion in two mouth wash samples.     

A novel lutetium(III) PVC membrane sensor based on a new symmetric S–N Schiff's base for Lu(III) analysis in real sample

A novel Lu(III) PVC membrane sensor has been constructed based on a new synthesized symmetric S–N Schiff's base, namely N-[(Z)-1-(2-thienyl)methylidene]-N-[4-(4-{[(Z)-1-(2-thienyl) methylidene]amino}benzyl)phenyl] amine (TBPA). The electrode showed a Nernstian slope of 19.8 ± 0.5 mV per decade across a wide concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with a detection limit of 7.2 × 10^? 7 mol L^? 1. The proposed sensor showed high selectivity toward Lu(III) ion in comparison with common alkaline, alkaline earth, transition, and heavy metals specially lanthanide ions, and could be used over a pH range of 2.7–10.6. It can be used for at least 2 months without any considerable divergency in potentials and it has a relatively fast response time of < 10 s. The sensor was effectively used as an indicator electrode in the potentiometric titration of Lu(III) ions with EDTA. The constructed sensor accuracy was investigated by the monitoring of Lu(III) ion in mixtures of two and three different ions.     

Optical and thermal properties of crystalline Tb: KLu(WO4)2

A single crystal of Tb: KLu(WO₄)₂ with dimensions of 40 mm × 40 mm × 18 mm has been grown by the top-seeded solution growth (TSSG) method. The color of the crystal is brown. Absorption and fluorescence spectra were measured at room temperature. The measured specific heat is a little lower than that of Yb: KLW (0.365 J/g K) at 90 °C. The measured mean linear coefficients of thermal expansion are α_a = 17.1643 × 10^− 6 K^− 1_, α_a^⁎ = 14.0896 × 10^− 6 K^− 1, α_b = 8.7938 × 10^− 6 K^− 1, α_c = 23.1745 × 10^− 6 K^− 1, α_c^⁎ = 20.2866 × 10^− 6 K^− 1. The results indicate that the crystal has a large anisotropy. The refractive index was measured.     

Highly sensitive amperometric sensor for micromolar detection of trichloroacetic acid based on multiwalled carbon nanotubes and Fe(II)–phtalocyanine modified glassy carbon electrode

A highly sensitive electrochemical sensor for the detection of trichloroacetic acid (TCA) is developed by subsequent immobilization of phthalocyanine (Pc) and Fe(II) onto multiwalled carbon nanotubes (MWCNTs) modified glassy carbon (GC) electrode. The GC/MWCNTs/Pc/Fe(II) electrode showed a pair of well-defined and nearly reversible redox couple correspondent to (Fe(III)Pc/Fe(II)Pc) with surface-confined characteristics. The surface coverage (Γ) and heterogeneous electron transfer rate constant (k_s) of immobilized Fe(II)–Pc were calculated as 1.26 × 10^? 10 mol cm^? 2 and 28.13 s^? 1, respectively. Excellent electrocatalytic activity of the proposed GC/MWCNTs/Pc/Fe(II) system toward TCA reduction has been indicated and the three consequent irreversible peaks for electroreduction of CCl₃COOH to CH₃COOH have been clearly seen. The observed chronoamperometric currents are linearly increased with the concentration of TCA at concentration range up to 20 mM. Detection limit and sensitivity of the modified electrode were 2.0 μM and 0.10 μA μM^? 1 cm^? 2, respectively. The applicability of the sensor for TCA detection in real samples was tested. The obtained results suggest that the proposed system can serve as a promising electrochemical platform for TCA detection.     

Preparation and characterization of copper nanoparticles/zinc oxide composite modified electrode and its application to glucose sensing

We report a new method for selective detection of d(+)-glucose using a copper nanoparticles (Cu-NPs) attached zinc oxide (ZnO) film coated electrode. The ZnO and Cu-NPs were electrochemically deposited onto indium tin oxide (ITO) coated glass electrode and glassy carbon electrode (GCE) by layer-by-layer. In result, Cu-NPs/ZnO composite film topography was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. SEM and AFM confirmed the presence of nanometer sized Cu-NPs/ZnO composite particles on the electrode surface. In addition, X-ray diffraction pattern revealed that Cu-NPs and ZnO films were attached onto the electrode surface. Indeed, the Cu-NPs/ZnO composite modified electrode showed excellent electrocatalytic activity for glucose oxidation in alkaline (0.1 M NaOH) solution. Further, we utilized the Cu-NPs/ZnO composite modified electrode as an electrochemical sensor for detection of glucose. This glucose sensor showed a linear relationship in the range from 1 × 10^? 6 M to 1.53 × 10^? 3 M and the detection limit (S/N = 3) was found to be 2 × 10^? 7 M. The Cu-NPs/ZnO composite as a non-enzymatic glucose sensor presents a number of attractive features such as high sensitivity, stability, reproducibility, selectivity and fast response. The applicability of the proposed method to the determination of glucose in human urine samples was demonstrated with satisfactory results.