Showing papers on "Reference electrode published in 1974"

Introduction to Bioelectrodes

Abstract: 1 Metallic Electrodes-Introduction.- 1.1. Electrode Materials.- 1.2. Electrode Geometry.- 1.3. Electrodes for Impedance Measurements.- 1.4. Metal Electrodes for Special Purposes.- 1.5. References.- 2 Alternating-Current Electrode Polarization.- 2.1. Introduction.- 2.2. Alternating-Current Electrode Polarization.- 2.3. Linear and Nonlinear Behavior.- 2.4. Fricke's Law.- 2.5. Electrode Platinizing Technique.- 2.6. Zero-Current Techniques.- 2.7. A Final Note: Circuit Models, pH and pO2.- 2.8. References.- 3 Electrode Polarization and Related Phenomena.- 3.1. Some Basic Definitions.- 3.1.1. Polarization.- 3.2. The Basic Voltammetric Measurement.- 3.3. Mass Transfer Considerations.- 3.3.1. Migration.- 3.3.2. Linear Diffusion.- 3.3.3. Convection.- 3.4. Some Electrode Reactions.- 3.5. References.- 4 Microelectrodes.- 4.1. Metal Microelectrodes.- 4.1.1. Etching.- 4.1.2. Insulating.- 4.2. Metal-Filled Glass Micropipette Electrodes.- 4.2.1. Low-Melting-Point Glass and High-Melting-Point Metal.- 4.2.2. High-Melting-Point Glass and Low-Melting-Point Metal or Metal Alloy.- 4.2.3. Metal-through-Glass Microelectrodes.- 4.3. Electrolyte-Filled Glass Microelectrodes.- 4.3.1. Electrode Pulling.- 4.3.2. Pipette Filling.- 4.4. Electrical Properties of Microelectrodes.- 4.4.1. Resistance of Microelectrodes.- 4.4.2. Equivalent Circuit for a Microelectrode.- 4.4.3. Electrical Noise in Micropipettes.- 4.5. Alternating-Current Electrode Polarization in Microelectrode Systems.- 4.5.1. Experimental Results.- 4.5.2. Photographic Records.- 4.6. Microelectrodes-A Few Final Notes.- 4.6.1. Noise in Glass Microelectrodes.- 4.6.2. Electrical Connections to Microelectrodes.- 4.6.3. Polarization Phenomena.- 4.6.4. Multiple Microelectrodes.- 4.6.5. pH Microelectrodes.- 4.6.6. Pore Electrodes.- 4.7. References.- 5 Half-Cells, Reversible and Reference Electrodes.- 5.1. Half-Cell Potentials.- 5.1.1. Debye-Huckel Theory.- 5.2. Specific Half-Cells and Reference Electrodes.- 5.2.1. The Silver-Silver Chloride Electrode.- 5.2.2. Fabrication of Ag-AgCl Electrodes.- 5.2.3. Standard Potential of Ag-AgCl Electrodes.- 5.2.4. Aging of Ag-AgCl Electrodes.- 5.2.5. Use of Ag-AgCl Electrodes.- 5.2.6. The Hydrogen Electrode.- 5.2.7. The Calomel Electrode.- 5.3. Salt Bridges.- 5.4. Reference Potential Cells-Standard Cells.- 5.5. Potentiometric Measurements.- 5.6. pH Electrodes and pH Meters.- 5.6.1. The Antimony and Quinhydrone Electrodes.- 5.6.2. The Glass Electrode.- 5.6.3. The pH Meter.- 5.7. References.- 6 Ion-Specific Electrodes.- 6.1. Special Considerations in the Use of Ion-Selective Electrodes.- 6.1.1. Calibration Curves.- 6.1.2. Use Extension of Existing Electrodes.- 6.2. Specific Membranes.- 6.2.1. Clay Membranes.- 6.2.2. Immobilized Liquid Membranes.- 6.2.3. "Permselective" Collodion Matrix Membranes.- 6.2.4. "Permselective" Noncollodion Membranes.- 6.2.5. Liquid Ion-Exchange Membranes.- 6.2.6. Mixed Crystal Membranes.- 6.3. The Glass-Membrane Electrode.- 6.3.1. Calibration.- 6.3.2. Correction for pH.- 6.4. Examples of Some Ion-Selective Electrodes.- 6.4.1. The Sodium and Potassium Electrode.- 6.4.2. The Calcium Electrode.- 6.4.3. Ammonia and Sulfur Dioxide Electrodes.- 6.5. The Oxygen Electrode.- 6.5.1. Appendix.- 6.6. The CO2 Electrode.- 6.7. Enzyme Electrodes.- 6.8. Antibiotic Electrodes.- 6.9. Ion-Specific Microelectrodes.- 6.10. Conclusion.- 6.11. References.- 7 Preamplifiers for Use with Bioelectrodes.- 7.1. Preamplifier Input Considerations.- 7.1.1. Special Considerations for Microelectrodes.- 7.2. Dynamic Response of Preamplifiers.- 7.2.1. Amplifier Gain.- 7.2.2. Bandwidth.- 7.2.3. Gain-Bandwidth Product.- 7.2.4. Transient Response and Risetime.- 7.3. Alternating-Current, Direct-Current, and Chopper-Stabilized Preamplifiers.- 7.3.1. Alternating-Current Preamplifiers.- 7.3.2. Direct-Current Preamplifiers.- 7.3.3. Direct-Current Offset.- 7.3.4. Chopper-Stabilized Preamplifiers.- 7.4. Active Components in Preamplifiers.- 7.5. Differential Amplifier.- 7.5.1. Common-Mode Signal.- 7.6. Operational Amplifiers.- 7.7. Electrometer Preamplifiers.- 7.7.1. Negative-Input-Capacitance Preamplifiers.- 7.8. The Voltage-Clamp Circuit and Feedback.- 7.9. Feedback.- 7.10. Isolation Networks.- 7.11. Noise.- 7.12. References.- 8 Specialized Electrodes.- 8.1. Body-Cavity Electrodes.- 8.2. Contoured Electrodes and Specialized Cardiac Electrodes.- 8.2.1. Flexible Electrodes.- 8.2.2. Other Chronic Electrodes.- 8.3. Anodized Electrodes.- 8.4. Self-Wetting Electrodes.- 8.5. Suction Electrode.- 8.6. Percutaneous Electrodes.- 8.7. Catheter and Other Flexible Electrodes.- 8.8. Spray-On Electrodes.- 8.9. Vapor-Deposited Electrodes.- 8.10. Miscellaneous Electrodes.- 8.11. Electrode-Anchoring Techniques.- 8.12. References.- 9 Signal-Analysis and Filtering Techniques.- 9.1. Representation of Complex Periodic Wave Forms.- 9.1.1. The Fourier Series.- 9.1.2. Numerical Fourier Analysis.- 9.2. Frequency Spectra of Aperiodic Functions.- 9.3. Extraction of Signals from Noise.- 9.3.1. Filters.- 9.3.2. Simple Filters.- 9.3.3. Fourier Comb Filters.- 9.3.4. Averaging Techniques.- 9.3.5. Switching Techniques.- 9.4. Conclusion.- 9.5. References.- 9.6. Bibliography.- 9.6.1. Signal Representation and Related Subjects.- 9.6.2. Statistical Treatment.- 9.6.3. Synthesis of Filter Networks.- 10 Appendix-Some Practical Matters.- 10.1. Measurement of Electrode Tip Size.- 10.2. Microelectrode Tip Potential.- 10.3. Shielding in EKG Recording.- 10.4. Distortion Produced by Stimulus-Isolation Units.- 10.5. Surface Drying of Preparation.- 10.6. Suction Electrodes-Precautions.- 10.7. Surface Impedance Measurement.- 10.8. Measurement of Electrode Series Resistance.- 10.9. Recessed-Electrode Cell for Impedance Determinations.- 10.10. A Further Note on Signal Distortion by Small Electrodes.- 10.11. References.- General Bibliography.- Electrode Processes and Electrochemistry.- Electronics for Scientists.- Electrodes: Types, Properties, and Fabrication.

Standard Potentials of Alkali Metals, Silver, and Thallium Metal/Ion Couples in N,N′-Dimethylformamide, Dimethyl Sulfoxide, and Propylene Carbonate

Abstract: The relative standard potentials of alkali metals, silver, and thallium metal/ion couples in N,N′-dimethylforrnamide(DMF), dimethyl sulfoxide(DMSO), and propylene carbonate (PC) were measured against an aqueous saturated calomel electrode(SGE). These standard potentials of lithium, sodium, potassium, rubidium, caesium, thallium, and silver are −3.237, −2.898, −3.116, −3.079, −3.079, −0.643, and +0.372 V vs. SGE respectively in DMSO, and −3.163, −2.830, −3.067, −3.040, −3.048, −0.559, and +0.538 V vs. SGE respectively in DMF, and −2.9064, −2.691, −3.002, −2.980, −2.986, −0.402, and +0.813 V vs. SGE respectively in PC. The thallium electrode was found to be stable enough to be used as a reference electrode in these solvents. For the purpose of examining the Debye-Huckel equation for estimating the activity coefficient, the formal potentials of the thallium electrode were measured at various ionic strengths. The Debye-Huckel equation was confirmed to be applicable in these solvents, provided a proper value w...

Electrochemical Studies of Uranium and Thorium in Molten LiF ‐ NaF ‐ KF at 500°C

Abstract: Electrochemical studies of U(IV) in molten Lif--NaF-KF (46.5-process at a platinum electrode. The first step is complicated by disproportionation of U(III) to regenerate U(IV); the second step involves formation of uranium metal. Standard electrode potentials with respect to a unit mole fraction Ni(II)/Ni electrode are estimated for the U(IV)/U(III) and U(III)/U couples as --1.41 and -- 1.81V, respectively. These values must be considered tentative because of complications in the electrode process. The voltammetric oxidation of U(IV) at platinum and pyrolytic graphite electrodes in LiF--NaF--KF occurs at ~+ 1.3V vs. a Ni(II) (saturated)/Ni reference electrode. The results point to the disproportionation of electrochemically generated U(V). In voltammetric studies of Th(IV) in molten LiF--NaF--KF at 500 deg C, a reduction wave is obtained at nickel and tungsten electrodes, with a peak potential of --2.02 V (vs. a Ni(II) (saturated)/Ni reference electrode). Analysis indicated that Th(IV) is reversibly reduced to the metal with alloy formation between the deposited thorium and the nickel. A standard electrode potential for the Th(IV)/Th couple in this melt is calculated to be -2.13V vs. a unit mole fraction Ni(II)/Ni electrode. (auth)

Miniature probe containing multifunctional electrochemical sensing electrodes

Abstract: A miniature probe contains multifunctional electrochemical electrodes which measure oxygen content or the hydrogen ion activity or pH of samples. One of these electrodes is contained within an oxygen sensor, one of these electrodes is contained within a carbon dioxide sensor while the other electrode can be coupled with a separate reference electrode or the reference electrode can surround the probe thereby providing a hydrogen ion activity or pH sensor. In this manner, the miniature probe contains an oxygen sensor, a carbon dioxide sensor and a pH electrode, or an oxygen sensor, a carbon dioxide sensor and a pH sensor.

Apparatus for measuring substrate concentrations

Abstract: The concentration of substrates of enzyme reactions is measured by determining the current produced at a platinum or gold electrode by oxidizing an acceptor utilizing a measuring device comprising a measuring cell, an enzyme electrode in contact with the fluid sample and containing a platinum or gold electrode, an enzyme layer and a reference electrode in contact with the fluid sample. In this manner important physiological parameters, such as the concentration of lactate and glucose in biological fluids, can be measured quickly and accurately.

Electrochemical reference electrode

Abstract: An electrochemical reference electrode for use in ion potential measurements of solutions. The liquid junction structure of the electrode comprises a hydrophobic polymer having a suitable salt distributed therethrough and held in place to prevent leaching by a filamentary structure of the polymer. The liquid junction structure is a diffusion membrane material and permits ionic communication between the salt bridge solution of the electrode and the sample solution essentially by means of diffusion, rather than by liquid flow. The entire electrode body may be made of the polymeric material. The electrode is particularly suited for process applications.

Apparatus for monitoring available chlorine in swimming pools

Abstract: An improved method and apparatus for the measurement of amounts of free available chlorine in solution which is independent of the pH have been developed. The apparatus includes a sensing electrode, which is internally buffered and self-cleaning, and a reference electrode supported within a container. A potential measuring means is connected between the electrodes. The solution containing the available chlorine is introduced to the container through an inlet and is released through an outlet. The improvement comprises employing as the sensing electrode a porous conductive material having means for internally supplying a pH control solution. Employing the apparatus, residual amounts of an oxidizing or reducing agent in solution can be continuously measured, independent of the pH of the solution. In addition, the electrode surface is continuously cleansed by the pH control solution. The method and apparatus of the present invention can be used, for example, to measure the free available chlorine concentration in swimming pool waters.

Portable polarographic analyzer and quick polarographic determinations

Abstract: A special purpose portable polarographic instrument and method for the rapid repetitive quantitative determination of polarographically reactive species in aqueous solution utilizing a sample cell in which are placed a conducting sample solution, a suitable reference electrode and a fixed area working electrode and, connected to the electrodes, a special circuit for (1) impressing across the cell a reducing or oxidizing voltage throughout a time linear pre-selected range of scanning potential, (2) proportionately converting the consequent current flow to a potential, and (3) measuring the potential. The maximum potential is retained in a peak seeking voltage circuit and is read on a voltmeter in a voltage follower circuit. The polarographic test utilizing the instrument is made more specific for O PARALLEL -C- compounds, such as aldehydes, by reacting the test sample in aqueous medium with a hydrazine acid addition salt at a pH of about 3 to 6.5 to form the hydrazone in aqueous medium which is detectable with great sensitivity and specificity. The working electrode may be underlying or may be suspended, but in any event, is best replaced or renewed or cleaned between determinations.

Electrode cell assembly for the continuous determination of ion concentrations in living tissues

Abstract: An electrode cell assembly for the continuous determination of ion concentrations in living tissues, which cell assembly comprises a measuring electrode having an ion selective member, which is shaped in a way so that it can be introduced into the living tissue and which cell assembly, furthermore, has a reference electrode in a housing which is filled with an electrolyte and which housing of the reference electrode has a membrane which is in continuous contact with the surface, e.g., the skin or the tissue of the living being during the determination of the ion concentrations, so that the ion concentration can be continuously read off from a recording device with which the electrode cell assembly is connected.

A potentiometric method for the determination of chloride in boiler waters in the range 0·1 to 10 µg ml–1 of chloride

Abstract: A potentiometric method for determining chloride in boiler water has been developed, which is based on the potential of a silver-silver chloride wire electrode versus a mercury(I) sulphate reference electrode immersed in a buffered solution of the sample. The method was tested in the range 0·1 to 10·0 µg ml–1 of chloride and the standard deviations of the results at 0·1, 1·76 and 10·0 µg ml–1 of chloride were approximately 0·04, 0·06 and 0·2 µg ml–1 of chloride, respectively. Substances normally present in boiler water do not interfere appreciably but the method is not suitable if octadecylamine is present.

Standard potentials of alkali metals, silver, and thallium metal/ion couples in n,n′-dimethylformamide, dimethyl sulfoxide, and propylene carbonate

Abstract: The relative standard potentials of alkali metals, silver, and thallium metal/ion couples in N,N′-dimethylforrnamide(DMF), dimethyl sulfoxide(DMSO), and propylene carbonate (PC) were measured against an aqueous saturated calomel electrode(SGE). These standard potentials of lithium, sodium, potassium, rubidium, caesium, thallium, and silver are −3.237, −2.898, −3.116, −3.079, −3.079, −0.643, and +0.372 V vs. SGE respectively in DMSO, and −3.163, −2.830, −3.067, −3.040, −3.048, −0.559, and +0.538 V vs. SGE respectively in DMF, and −2.9064, −2.691, −3.002, −2.980, −2.986, −0.402, and +0.813 V vs. SGE respectively in PC. The thallium electrode was found to be stable enough to be used as a reference electrode in these solvents. For the purpose of examining the Debye-Huckel equation for estimating the activity coefficient, the formal potentials of the thallium electrode were measured at various ionic strengths. The Debye-Huckel equation was confirmed to be applicable in these solvents, provided a proper value w...

Use of hydrogen-absorbing electrode in alkaline battery

Abstract: Alkaline batteries are described in which a special electrode is incorporated in the positive electrode in order to give added protection against electrochemical damage due to battery reversal. This special electrode contains a hydrogen-absorbing material which also acts as a hydrogen electrode for the conversion of hydrogen ions into elemental hydrogen. Such alkaline batteries are particularly well protected against hydrogen overpressure due to battery reversal with only a small penalty in energy density. Particularly suitable for this application is the use of a hydrogen-absorbing material with nominal formula LnM5 in which Ln represents a lanthanide metal and M is either cobalt or nickel.

The simultaneous measurement of pH, chloride and electrolytic conductivity in soil suspensions

Abstract: The measurements of pH, chloride and electrolytic conductivity have been simplified and made simultaneous for suspensions of soil in water through the use of a triple electrode system mounted in a single unit. A glass electrode and a silver-silver chloride electrode with a common reference electrode and two pH meters are used for the determination of pH and chloride, respectively. Electrolytic conductivity is measured by an ohm-meter principle using silver electrodes. The outputs of the three meters are recorded on a three-pen recorder with electrically independent channels. The pH, over the range 0 to 10, is read from the chart while the values for chloride and electrolytic conductivity are obtained from graphs or tables. Once the instruments are set up they need little adjustment during the day.

Method of chelometric titration of metal cations using tungsten bronze electrode

Abstract: A chelating agent of known concentration is added to a solution containing an unknown quantity of a metal cation. An electrode formed from an alkali metal tungsten bronze crystal is placed in the solution together with a reference electrode and the potential difference between the two is measured. At the end point of the titration, an abrupt and substantial negative potential shift is observed at the tungsten bronze electrode. Reverse titrations are also possible with these electrodes.

Bicarbonate ion electrode and sensor

Abstract: A bicarbonate ion electrode is described which has an electrode lead, an electrochemically active region of silver and a silver halide other than a fluoride at one end thereof, an electrolyte containing at least the bicarbonate ion to be detected and an ion which enters into electrochemical equilibrium with the active region of the lead in contact with the active region, a hydrogen ion permeable membrane encapsulating the active region and the electrolyte, and electrical insulation covering the remaining portion of the electrode lead. When the potential of the electrode is measured with respect to that of an external reference electrode, a bicarbonate ion sensor is provided.

Apparatus for pH measurements

Abstract: Electrolyte container for saturated potassium chloride solutions used as an electrolytic bridge between sensitive portions of a flow-through pH electrode and a pH reference electrode. The container inhibits so-called "KCl creep" from the solution and consists of an essentially closed polymeric container having means which define separate orifices through which sensitive portions of the electrodes can be inserted for electrical contact with the solution, the orifice defining means also serving to retain the housings of the electrodes in a sealing relationship to the solution. Preferably, the orifice defining means and electrode retention means consist of resilient silicone electrode retaining rings or sealing glands which form a portion of at least one wall of the container which is preferably made from a transparent cast acrylic resin.

Method of determining hydrogen cyanide

Abstract: An improved gas-sensing electrochemical cell for measuring hydrogen cyanide gas in a sample solution. The cell comprises a potentiometric silver ion-sensitive electrode and a reference electrode, both in contact with an internal standard solution comprising an aqueous solution of an argento cyanide complex. A hydrophobic hydrogen cyanide gas-permeable membrane separates the sample solution from the internal solution.