Studies on the Coordination of Pr(Ⅲ) with Adrenaline by Potentiometry and Absorption Spectroscopy

The stability constant for complex of Pr(Ⅲ) with adrenaline has been determined by potentiometric titration under biological conditions (37℃ and 0.15mol/L NaCl). The absorption spectra of the Pr(Ⅲ)-adrenaline system exhibit characteristic bands of Pr(Ⅲ) at lower pH values. However, the charge transfer band which is due to the coordination of Pr(Ⅲ) with adrenaline has been observed at higher pH values.

Carbon Nanotubes as Nanosensor for Differential Electrolytic Micropotentiometry

Carbon nanotubes as nanosensor were synthesized on the surface of the silver electrode using floating catalyst chemical vapor deposition reactor. Acetylene gas was used as a carbon source, ferrocene as a source of the iron nanocatalyst and hydrogen as a carrier and an activate agent. Several runs were performed to find the optimum conditions that produce sensitive Ag-CNTs electrodes. The electrodes obtained at each run were characterized by SEM. The optimum conditions that produce sensitive Ag-CNTs were found to be at a reaction time of 15 minutes, reaction temperature of 700°C, hydrogen flow rate of 25 ml/min and an acetylene flow rate of 75 ml/min. These optimum conditions were confirmed from the normal behavior of the resulting Ag-CNTs electrodes in the titration of 10 μL of chloride using dc differential electrolytic potentiometry. When conditions that differ from the optimum ones were applied in the preparation of the Ag-CNTs electrodes, abnormal titration curves were obtained. The superiority of the Ag-CNTs electrodes was demonstrated by the successful applications of these electrodes as an indicating system in the micro titrations of different volumes of cyanide solution with silver nitrate reach. By applying this technique a volume of 1.2 μL sample of cyanide was successfully titrated. The normal behavior of the Ag-CNts electrodes was compared to that of the normal silver electrodes which exhibit an abnormal behavior.

Determination of Stability Constants of Cadmium-Glycine Complexes by a Unified Treatment for Potentiometric and Polarographic Data

The cadmium（Ⅱ）-glycine system was studied by the two experimental techniques, ion sensitive electrode （ISE） and differential pulse polarography （DPP）, and the experimental data obtained were used by a unified mathematical treatment to calculate the complex stability constants. The combination of the two techniques is of many advantages as ISE can be performed at low [LT]：[MT] ratios and significantly higher [MT], whereas DPP could be used well at large [LT]：[MT] ratios and much smaller [MT]. This makes it possible to study a metal-ligand system in a relatively broader range of experimental conditions that, in turn, provides more information about the metakligand system of interest. Applying the unified mathematical treatment to the cadmium-glycine system, two new complexes MHL and ML2（OH） as well as three complexes ML, ML2 and ML3, reported in literatures, could be modeled and all their stability constants have been refined.

Potentiometric detection of polyions based on functionalized magnetic nanopaiticles

A novel potentiometric detection strategy based on functionalized magnetic nanoparticles has been developed for rapid and sensitive sensing of polyions.Highly dispersed magnetic nanoparticles coated with ion exchanger and plasticizer could promote an in situ cooperative ion-pairing interaction between the ion exchanger and the polyion analyte in sample solution by dramatically reducing the mass-transfer distance.With applying a magnetic field,the nanoparticles can be attached to the surface of ion exchanger free polymeric membrane.The observed potential signals are related to the polyion concentrations.The proposed polymeric membrane electrode exhibits a linear relationship between the greatest potential response slope（dE/dt） and the logarithm of protamine concentration in the range of 0.05-5μg/mL with a lower detection limit of 0.033μg/mL.

Cyclam Modified Carbon Paste Electrode as a Potentiometric Sensor For Determination of Cobalt(Ⅱ) Ions

A new modified carbon paste electrode based on cyclam as a modifier was prepared for the determination of Co(Ⅱ) ions. The proposed electrode shows a Nernstian slope 28.4 mV per decade over a wide concentration range 5.0×10 -6_1.0×10 -1 mol/L of Co 2+ ions with detection limit 2.5×10 -6 mol/L. The sensor exhibits good selectivities for Co 2+ over a wide variety of other cations. It can be used as an indicator electrode in potentiometric titration of cobalt(Ⅱ) ions as well as in direct determination of cobalt(Ⅱ) ions in wastewater of acidic cobalt electroplating bath. The electrode shows Nernestian behavior in a solution of 25% ethanol.

Potentiometric Determination of Chloride and Cyanide Ions in Nanoliter Samples with Capillary Indicating Electrodes

The samples of 25 nL of chloride and cyanide were determined with a kind of glass capillary indicating electrodes by potentiometry. Silver was deposited by the silvermirror reaction on the inner surface of the glass capillary with a volume of 25 nL. The AgCl film and the AgI film were formed by the treatment of the capillary with a FeCl 3 solution and further with a KI solution. The samples were collected automatically into the capillary by the capillary ascension. The procedure in the measurement was merely to place a reference electrode and a capillary indicating electrode vertically on a strip filter paper containing a 01 mol/L NaNO 3 solution. The various i.d. of the capillary electrodes were used to determine samples ranging from 25 nL to dozens of microliters. The ranges of the linear response to chloride and cyanide were 32×10 -4 —22×10 -1 mol/L and 10×10 -5 —10×10 -1 mol/L with an average slope of 552 and 52—62 mV/decade , respectively. The samples with various concentrations of chloride and cyanide were determined, and the relative standard deviations were less than 7%.

Potentiometric determination of diclofenac in pharmaceutical formulation by membrane electrode based on ion associate with base dye

The characteristics, performance and application of membrane electrode based on ion associate of diclofenac with base dye Safranine T are described. The electrode response to diclofenac has the sensitivity of 47 ± 1.0 mV decade(?1) over the range of 5 × 10(?5) to 5 × 10(?2) mol/L at pH 6–12, and the detection limit of 3.2 × 10(?5) mol/L. The electrode is easy assembled at a relatively low cost has fast response time (2–4 s) and can be used for a period up to 3.5 months without any considerable divergence in potential. The proposed sensor displayed good selectivity for diclofenac in the presence of different substances. It was used to determine diclofenac in pharmaceuticals by means of the standard addition method.

In situ modifed screen printed and carbon paste ion selective electrodes for potentiometric determination of naphazoline hydrochloride in its formulation

The construction and performance characteristics of new sensitive and selective in situ modified screen printed （ISPE） and carbon paste （ICPE） electrodes for determination of naphazoline hydrochloride （NPZ-HC1） have been developed. The electrodes under investigation show potentiometric response for NPZ-HC1 in the concentration range from 7.0 x 10-7 to 1.0 x 10-2 M at 25 ~C and the electrode response is independent of pH in the range of 3.1-7.9. These sensors have slope values of 59.7＋0.6 and 59.2＋0.2 mV decade-l with detection limit values of 5.6 ~ 10-7 and 5.9 x 10-7 M NPZ- HC1 using ISPE and ICPE, respectively. These electrodes show fast response time of 4-7 s and 5-8 s and exhibits lifetimes of 28 and 30 days for ISPE and ICPE, respectively. Selectivity for NPZ-HC1 with respect to a number of interfering materials was also investigated. It was found that there is no interference from the investigated inorganic cations, anions, sugars and other pharmaceutical excipients. The proposed sensors were applied for the determination of NPZ-HC1 in pharmaceutical formulation using the direct potentiometric method. It showed a mean average recovery of 100.2% and 102.6% for ISPE and ICPE, respectively. The obtained results using the proposed sensors were in good agreement with those obtained using the official method. The proposed sensors show significantly high selectivity, response time, accuracy, precision, limit of detection （LOD）and limit of quantification （LOQ） compared with other proposed methods.

Determination of Trace Molybdenum(VI) by Oscillographic Potentiometric Catalyzing Kinetic Method of Simplex Optimization

Under the optimum experimental conditions (i. e., pH=1.6, c KI=10.6 mmol/L, =5.4 mmol/L, =1.30 mmol/L) derived from simplex operations, trace molybdenum(VI) was determined through the agency of its catalytic effect on the reaction of H2O2 with I? in acid medium. The detection limit and linear calibration range of molybdenum were obtained as 0.5×10?6 mol/L and 0.5×10?6～120×10?6mol/L respectively. This method was applied to the examination of the industrial waste water, and the recovery ratios were found to be in the range of 101% and 107%. Key words oscillographic potentiometry - catalyzing kinetic analysis - simplex optimization - molybdenum Supported by the National Natural Science Foundation of China (Grant No. 20175013) and the Higher Education Development Foundation of Shanghai in China (Grant No. 01A17)

Differential Electrolytic Potentiometric, a Detector for FIA Determination of Procainamide in Pharmaceutical Preparations

Differential electrolytic potentiometry （DEP） was coupled with Flow injection analysis （FIA） technique for the determination of Procainamide in pharmaceutical preparations. Platinum electrodes were used as an indicating system to follow the oxidation of Procainamide with cerium（IV）, and permanganate in an acidic medium. The oxidation reactions of Procainamide with Ce（IV） and/or permanganate are fast enough to permit its determination by flow injection in sulfuric acid media. The univariate method was employed to optimize the variables such as the current density, the flow rate, the oxidant concentration and the concentration of sulfuric acid. The proposed method was linear in the range 20-100 μg.mL^-1 , the DL and R2 values were 12 μg.mL^-1 and 0.995 respectively. The procedure was applied successfully to the determination of Procainamide in commercial tablets. The results of this study were favorably compared statistically with those obtained with official methods.

Analytical expressions of steady-state concentrations of species in potentiometric and amperometric biosensor

A mathematical model of potentiometric and amperometric enzyme electrodes is discussed. The model is based on the system of non-linear steady-state coupled reaction diffusion equations for Michaelis-Menten formalism that describe the concentrations of substrate and product within the enzymatic layer. Analytical expressions for the concentration of substrate, product and corresponding flux response have been derived for all values of parameters using Homotopy analysis method. The obtained solution allow a full characterization of the response curves for only two kinetic parameters (The Michaelis constant and the ratio of overall reaction and the diffusion rates). A simple relation between the concentration of substrate and products for all values of parameter is also reported. All the analytical results are compared with simulation results (Scilab/Matlab program). The simulated results are agreed with the appropriate theories. The obtained theoretical results are valid for the whole solution domain.

Imprinted Polymer Inclusion Membrane Based Potentiometric Sensor for Determination and Quantification of Diethyl Chlorophosphate in Natural Waters

Biomimetic potentiometric sensor for the determination of diethyl chlorophosphate was developed using im- printed polymer inclusion membrane strategy. Semi-covalent imprinted and non-imprinted polymer particles were synthesized and found that non-imprinted polymer inclusion membrane was unstable in contrast to im- printed polymer inclusion membrane in determination and quantification of diethyl chlorophosphate. Im- printed polymer inclusion membrane based sensor found to be pH dependant with a 5 min equilibrium response time at pH = 10.5 and linearly responds to diethyl chlorophosphate in the concentration range of 1 × 10–9 to 1 × 10–4 and 1 × 10–4 to 1 × 10–1 mol●L–9 with a detection limit of 1 × 10–9 mol●L–1 (0.17 ppb). It was found that diethyl chlorophosphate response was selective against various selected interferents like pinacolyl methylphosphonate, dimethyl methyl phosphonate, methylphosphonic acid, Phorate and 2, 4-D. The devel- oped sensor was found to be stable for 3 months and can be reusable more than 30 times without loosing sensitivity. The developed sensor was successfully applied for the determination of diethyl chlorophosphate in natural waters.

Elucidation of Abnormal Potential Responses of Cation-Selective Electrodes with Solid-State Membranes to Aqueous Solutions of CuCl2 and CdI2

An empirical solution to abnormal potential responses, showing peaks of emf, of commercial Cu2+- and Cd2+-selective electrodes with solid-state membranes was proposed for aqueous solutions of CuCl2 and CdI2. The two-step processes of Mn+ + Yn? (s: solid phase) MY(s) and MY(s) + 2X? X2MY2?(s) (n = 1, 2) at a test solution/electrode-interface were considered as a model. Here, Mn+, Yn?, and X? refer to a divalent or univalent cation, functional groups of electrode materials, and a halide ion (X? = Cl?, Br?, I?), respectively. By applying electrochemical potentials to these processes at n = 2, we derived an equation. Regression analyses based on the equation reproduced well the plots of emf versus log 2(*[M]t) for the Cd(II) and Cu(II) systems: *[M]t denotes a total concentration of species relevant to M2+ in a bulk of the aqueous solution. Also, we obtained log Ks(CdBr2) = 4.28 ? 0.22, log Ks(CdI2) = 6.98 ? 0.05, log Ks(CuCl2) = 3.96 ? 0.09, and log Ks(CuBr2) = 11.4 at 25?C. The magnitude in ?log Ks reflected that in the logarithmic solubility product, log {*[M2+](*[X?])2}, for bulk water, where *[M2+] or *[X?] denotes a molar concentration of the bulk solu-tion of M2+ or X? at equilibrium, respectively. Moreover, a mixture of CuSO4 with NaCl at the molar ratio of 1:1 yielded a plot similar to that of CuCl2.

Potentiometric, spectrophotometric, conductimetric and thermodynamic studies on some transition metal complexes derived from 3-methyl-1-phenyl- and 1, 3-diphenyl-4-arylazo-5-pyrazolones

A new 3methyl1phenyl4arylazo5pyrazolone and 1, 3diphenyl4arylazo5pyrazolone have been synthesized and characterized by elemental analysis, IR, mass and 1H NMR spectra. The acid dissociation constants (pKa values) of the investigated ligands were determined potentiometrically and spectrophotometrically. The stability constants of the transition metal ions (VO2+, Cr3+, Mn2+, Co2+, Ni2+, Cu2+ and Zn2+) with the investigated ligands were determined potentiometrically at different ionic strengths (0.167, 0.1, 0.05 and 0.025 M) NaCl at 25oC and different temperature (25, 30, 35, and 45oC). The values of stability constants were found to decrease with increasing ionic strengths and temperature. The stoichiometries were studied using spectrophotometric and conductimetric methods, the results indicate the existence of 1:1 and 1:2 (M:L) metal:ligand species. The relationships between the stability constants of the complexes, ionization constants of the ligands have been discussed and correlated. The thermodynamic parameters (?G, ?H and ?S) and the thermodynamic stability constants for all of the investigated complexes were determined potentiometrically.

Identification and Quantification of Intracoordination Water in Insoluble Pectinates Cu²⁺and Pb²⁺

By derivatography in insoluble pectins Cu2+ (РCu2+) and Pb2+ (РPb2+), the presence of “a high-temperature component” (150°C- 165°C) is established. During potentiometric alkalimetric titration of РCu2+ and РPb2+, endpoints are established at рН accordingly 4.87 and 4.95, proving acid properties of PM. Obtained data show the presence of water in the internal sphere of PM. Considering the loss of this water and the known ratio of metal cations and monomers of pectin (L-), the simplest formulas of pectins are established: [Cu(L-)2(H2O)2], [Pb(L-)2(H2O)4].

A New Potentiometric Sensor for Determination of Pethidine hydrochloride in Ampoules and Urine

A simple, precise, rapid and low-cost potentiometric method for pethidine determination in pharmaceuticals and urine is proposed. A chemically modified carbon paste electrode (CMCPE) for pethidine hydrochloride (PDCl) based on pethidine-phosphotungstate (PD-PT) as ion-pair complex was prepared and fully character-ized in terms of composition, usable pH range, response time and temperature. The pethidine electrode showed Nernstain responses in the concentration range 2.1 × 10–6-1.0 × 10–2 M with a detection limit of 7.3 × 10-7 and usable within the pH range 3.5-6.6. This sensor exhibited a fast response time (about 5-8 s), good stability. The value (dE/dt) of the electrode was found to be 0.00071 V/?C, which indicates fairly high ther-mal stability. Selectivity coefficients determined by matched potential method (MPM) and separate solution method (SSM) showed high selectivity for PDCl with respect to a large number of inorganic cations, organic cations, sugars and some common drug excipients. The sensor could be used successfully in the estimation of PDCl in ampoules and in spiked urine samples.

Potentiometric Determination of Stability Constants of Sulphathiazole and Glycine-Metal Complexes

Binary and ternary complexes of (Fe(III), Pb(II), Co(II), Al(III), La(III), Sr(II), Cr(III), Ti(II) and Zr(II)) with sulphathiazole (as primary ligand) and amino acid glycine (as secondary ligand) have been studied potentiometrically at 25°C ± 0.1°C and I = 0.1 M NaClO4 in 25% (v/v) pure ethanol-water medium. Although there are many methods available to study the stability of metal-ligand complexes, pH-metry is most frequently used. In extension of our study on solution equilibria, we used Calvin-Bjerrum method for the calculation of stability constants. Stoichiometries and stability constants of binary systems containing the above metal ions in a 1:1 and 1:2 and/or 1:3 ratios were also determined to compare the effect of the secondary ligand on (1:1) Metal:Sulphathiazole system. The protonation constants of the complexes were evaluated for the system M:Sulphathiazole:Glycine = 1:1:1. The order of stability of the binary and ternary complexes was examined. It was found that glycine adds preferably [M-Sulfathiazole] rather than to the aqueous complexes of metal ions. In all cases 1:1:1 complex was formed.

面神经F波研究

F波是周围神经在阈上超强刺激条件下，由逆行冲动引起的运动神经纤维的非突触性反应。F波最显著的特点是能够反映神经全程的功能状态。目前国内外各项神经F波相关研究在周围神经病中已逐渐成为常规检查手段，尤其对整个神经特别是近端神经的运动传导功能可做出早期估价。面神经是人体在骨管内走形最长的脑神经，应用F波可全程、早期的检测其功能状态。

Electrochemical Biosensor for Rapid Detection of Viable Bacteria and Antibiotic Screening

We have developed a biosensor for the detection of live/viable bacteria based on the response of the conductive polymer 4-(3-pyrrolyl)butyric acid to glucose-induced metabolites.The polymer was electrochemically deposited and then functionalized with lectin through EDC/NHS chemistry to capture cells near the sensor surface and introduce selectivity for analytes.The addition of glucose to a three-electrode electrochemical cell containing 10 mM phosphate buffer and the bacteria-immobilized sensor produced an increase in the potential.When the bound bacteria were treated with antibiotics,the addition of glucose produced a notably reduced signal exhibiting the sensor’s potential to screen for the most effective antibiotic treatment.This biosensor having real-time responses,minimal sample preparation,and the ability to screen antibiotics demonstrates the speed,ease,and suitability essential for application in point-of-care services.The detection range was determined to be 6.0×10^(3)-9.2×10^(7)CFU/mL.

Erbium(Ⅲ) PVC membrane sensor based on N-(benzyloxycarbonyloxy)succinimide as a new neutral ionophore

In this study,a new Er^3＋ sensor based on N-（benzyloxycarbonyloxy）succinimide（BCS） as a neutral carrier has been constructed. The sensor exhibits potential linear response with a Nernstian slope of 20.5±0.4 mV/decade in the concentration range of 1.0×10^-6to 1.0×10^-2mol/L of Er^3＋.It has a very short response time（10 s）,detection limit of 6.3×10^-7 mol/L and a good selectivity relative to a wide variety of other metal ions including common alkali,alkaline earth,heavy,and transition metal ions.It can be used in the pH range of 2.5-10.6 without any considerable divergence in potentials.The proposed sensor was successfully applied for the recovery of Er^3＋ ions spiked in tap and river water samples.