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

Mosbach, M.; Laurell, Thomas LU ; Nilsson, J.; Csöregi, Elisabeth LU and Schuhmann, W. (2001) In Analytical Chemistry 73(11). p.2468-2475
Abstract
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
STATIONARY DISK ELECTRODES, FLOW-THROUGH DISPENSER, CHRONOAMPEROMETRY, MALDI
in
Analytical Chemistry
volume
73
issue
11
pages
2468 - 2475
publisher
The American Chemical Society
external identifiers
  • wos:000169063000025
  • scopus:0035356898
ISSN
1520-6882
DOI
10.1021/ac0012501
language
English
LU publication?
yes
id
484dea29-6b6b-40d5-80fa-4166b0554c37 (old id 2376425)
date added to LUP
2012-03-23 09:06:59
date last changed
2018-01-21 03:26:10
@article{484dea29-6b6b-40d5-80fa-4166b0554c37,
  abstract     = {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.},
  author       = {Mosbach, M. and Laurell, Thomas and Nilsson, J. and Csöregi, Elisabeth and Schuhmann, W.},
  issn         = {1520-6882},
  keyword      = {STATIONARY DISK ELECTRODES,FLOW-THROUGH DISPENSER,CHRONOAMPEROMETRY,MALDI},
  language     = {eng},
  number       = {11},
  pages        = {2468--2475},
  publisher    = {The American Chemical Society},
  series       = {Analytical Chemistry},
  title        = {Determination of diffusion coefficients of electroactive species in time-of-flight experiments using a microdispenser and microelectrodes},
  url          = {http://dx.doi.org/10.1021/ac0012501},
  volume       = {73},
  year         = {2001},
}