Clark electrode

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Clark-type electrode: (A) Pt- (B) Ag/AgCl-electrode (C) KCl electrolyte (D) teflon membrane (E) rubber ring (F) voltage supply (G) galvanometer

The Clark electrode ^[1][2] is an electrode that measures oxygen on a catalytic platinum surface using the reaction:

O₂ + 2 e⁻ + 2 H₂O → H₂O₂ + 2 OH⁻

[edit] Application

Electron flow to oxygen as a result of oxidative phosphorylation can be demonstrated using an oxygen electrode. The electrode compartment is isolated from the reaction chamber by a thin Teflon membrane; the membrane is permeable to molecular oxygen and allows this gas to reach the cathode, where it is electrolytically reduced.

The reduction allows a current to flow; this creates a potential difference which is recorded on a flatbed chart recorder. The trace is thus a measure of the oxygen activity of the reaction mixture. The current flowing is proportional to the activity of oxygen provided the solution is stirred constantly (mechanical flea) to minimize the formation of an unstirred layer next to the membrane.

Reference: Trinity College Dublin, Biochemistry Laboratory Manual for Senior Freshman Science, 2005-2006. www.tcd.ie/biochemistry

[edit] References

1. ^ Clark LC, Wolf R, Granger D, Taylor Z (1953). Continuous recording of blood oxygen tensions by polarography. J Appl Physiol. 6, 189-193. PMID 13096460
2. ^ Severinghaus JW, Astrup PB (1986). History of blood gas analysis. IV. Leland Clark's oxygen electrode. J Clin Monit. 2, 125-139. PMID 3519875

[edit] External links

• Biosensors & Bioelectronics: Leland Clark-link down?
• Clark Oxygen Electrode, presursor to today's modern biosensors

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