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Automatic electrochemical micro-pH-stat for biomicrosystems.
- Source :
-
Analytical chemistry [Anal Chem] 2008 Feb 15; Vol. 80 (4), pp. 905-14. Date of Electronic Publication: 2008 Jan 11. - Publication Year :
- 2008
-
Abstract
- A microelectrochemical pH-stat with an automatic feedback function was fabricated. The operation of the device is based on the nonstandard use of an electrochemical three-electrode system with a pH-sensitive reference electrode, a Ag/AgCl working electrode, and an iridium auxiliary electrode that functions as an actuator to adjust the solution pH. The combination of the electrodes caused a negative feedback in response to a pH change. The shift of the potential of the pH-sensitive reference electrode caused an overpotential on the Ag/AgCl working electrode, which then caused a significant current increase. This led to the electrolysis of water on the auxiliary electrode and the rapid recovery of the pH. The negative feedback function to stabilize the initial state could be confirmed for changes to both the acidic and basic directions. The performance of the pH-stat was characterized in the titration of acetic acid or ammonia. The charge generated in the feedback process changed linearly with respect to the concentration. The pH-stat was also used in the determination of urea by urease and that of the activities of trypsin and pepsin while maintaining the optimum pH for the enzymes. The pH to be fixed could be changed by changing the working electrode potential. Moreover, the two pH-stats could be used to form a pH gradient in a microflow channel by fixing the pH values at two positions.
- Subjects :
- Acetic Acid chemistry
Ammonia chemistry
Animals
Biosensing Techniques instrumentation
Electrodes
Gastric Juice enzymology
Hydrogen-Ion Concentration
Iridium chemistry
Male
Pepsin A metabolism
Rats
Rats, Wistar
Silver chemistry
Silver Compounds chemistry
Time Factors
Trypsin metabolism
Urea metabolism
Urease metabolism
Automation
Biosensing Techniques methods
Electrochemistry methods
Urea analysis
Subjects
Details
- Language :
- English
- ISSN :
- 0003-2700
- Volume :
- 80
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Analytical chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 18186613
- Full Text :
- https://doi.org/10.1021/ac071286u