Tag Archives: electrochemistry

Solid Electrodes

Schematic diagram showing a solid electrode. The electrode is fashioned into a disk and sealed in the end of an inert polymer support along with an electrical lead.

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Potential Windows for Hg, Pt, and C Electrodes

The approximate potential windows for mercury, platinum, and carbon (graphite) electrodes in acidic, neutral, and basic aqueous solvents are shown here. The useful potential windows are displayed in green; potentials in red result in the oxidation or reduction of the … Continue reading

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Mercury Electrodes

Three examples of mercury electrodes are illustrated here: (a) hanging mercury drop electrode, or HMDE; (b) dropping mercury electrode, or DME; and (c) static mercury drop electrode, or SMDE. In the hanging mercury drop electrode, or HMDE, a drop of … Continue reading

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External Generation of Oxidizing Agents or Reducing Agents

Shown here is one example of a device for the external generation of oxidizing agents and reducing agents for controlled-current coulometry. A solution containing the mediator flows into a small-volume electrochemical cell. The resulting oxidation products, which form at the … Continue reading

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Controlled-Current Coulometry

A second approach to coulometry is to use a constant current in place of a constant potential, which produces the current–time profile shown here. Controlled-current coulometry has two advantages over controlled-potential coulometry. First, the analysis time is shorter because the … Continue reading

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Controlled-Potential Coulometry

Coulometry is based on an exhaustive electrolysis of the analyte. By exhaustive we mean that the analyte is completely oxidized or reduced at the working electrode or that it reacts completely with a reagent generated at the working electrode. During an … Continue reading

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Disposable ISE

Schematic diagram of a disposable ion-selective electrode created by screen-printing. In (a) a thin film of conducting silver is printed on a polyester substrate and a film of Ag2S overlaid near the bottom. In (b) an insulation layer with a … Continue reading

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Enzyme Electrode

A gas-sensing electrode can be modified to create a potentiometric electrode that respond to a biochemically important species, such as enzymes. One example of an enzyme electrode is the urea electrode, which is based on the catalytic hydrolysis of urea by … Continue reading

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Gas-Sensing Membrane Electrode

A number of membrane electrodes respond to the concentration of a dissolved gas. The basic design of a gas-sensing electrode consists of a thin membrane that separates the sample from an inner solution containing an ion-selective electrode. The membrane is … Continue reading

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Liquid Membrane Ion-Selective Electrode

Another class of ion-selective electrodes uses a hydrophobic membrane containing a liquid organic complexing agent that reacts selectively with the analyte. Three types of organic complexing agents have been used: cation exchangers, anion exchangers, and neutral ionophores. One example of … Continue reading

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