The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Determination of diffusion coefficients of electroactive species in time-of-flight experiments using a microdispenser and microelectrodes

På svenska

Author

  • M. Mosbach
  • Thomas Laurell
  • J. Nilsson
  • Elisabeth Csöregi
  • W. Schuhmann

Summary, in English

Two novel methods for the determination of diffusion coefficients of redox species combining the special properties of microdispensing devices and microelectrodes are presented Both are based on the local application of tiny volumes of the redox-active species by means of a dispenser nozzle at a defined distance from the surface of a microelectrode. The microelectrode, which is inserted through the bottom into an electrochemical cell, is held at a constant potential sufficient to oxidize or reduce the electro-active species under diffusional control. The dispenser, which is filled with the electro-active species, can be positioned by means of micrometer screws over the microelectrode, After dispensing a defined number of droplets near the microelectrode surface, the current through the microelectrode is recorded, usually yielding a peak-shaped curve having a defined time delay between the shooting of the droplets and the maximum current, The time that is necessary to attain maximum current, together with the known distance between two dispensing points, can be used to determine the diffusion coefficient of the electroactive species without knowledge of any system parameters, such as concentration of the redox species, diameter of the electroactive surface or number of transferred electrons. A similar method for the determination of diffusion coefficient of redox species involves a second redox species for calibration purposes. A mixture of both species is shot close to the microelectrode surface. Due to the different formal potentials of the redox species that are used, they can be distinguished in sequential experiments by variation of the potentials that are applied to the microelectrode, and it is thus possible to determine the individual transit times of the redox species independently. The difference in the transit times, together with the known diffusion coefficient of one of the redox species, can be used to calculate the unknown diffusion coefficient of the second one.

Publishing year

2001

Language

English

Pages

2468-2475

Publication/Series

Analytical Chemistry

Volume

73

Issue

11

Document type

Journal article

Publisher

The American Chemical Society (ACS)

Topic

  • Analytical Chemistry

Keywords

  • STATIONARY DISK ELECTRODES
  • FLOW-THROUGH DISPENSER
  • CHRONOAMPEROMETRY
  • MALDI

Status

Published

ISBN/ISSN/Other

  • ISSN: 1520-6882