Quantitative measurements of NO reaction kinetics with a Clark-type electrode

Xiaoping Liu, Qihui Liu, Era Gupta, Nicholas Zorko, Emma Brownlee, Jay L. Zweier

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Nitric oxide (NO) plays important physiological roles in the body. Knowledge regarding the kinetics of NO catabolism is important for understanding the biological functions of NO. Clark-type NO electrodes have been frequently employed in measuring the kinetics of NO reactions; however, the slow response time of these electrodes can cause measurement errors and limit the application of the electrode in measurements of fast NO reactions. In this study, a simplified diffusion model is given for describing the response process of the NO electrode to the change of NO concentration. The least-square method is used in fitting the currents calculated from the diffusion equation to the experimental curves for determining the diffusion parameters and rate constants. The calculated currents are in excellent accordance with the experimental curves for different NO reaction kinetics. It has been demonstrated that when using an NO electrode with a response time of ∼6 s to measure fast NO reactions with a half-life of ∼1 s, the response currents of the electrode have large differences compared to the curve of actual NO concentration in the solution; however, the rate constant of NO decay can still be accurately determined by computer simulations with the simplified diffusion model. Theoretical analysis shows that an NO electrode with a response time of 6 s (D/L2 = 0.06 s-1) and the lowest detection limit of 1 nM NO can be used in measuring kinetics of extremely rapid NO reactions with a half-life below 10 ms.

Original languageEnglish (US)
Pages (from-to)68-77
Number of pages10
JournalNitric Oxide - Biology and Chemistry
Issue number1
StatePublished - Aug 2005
Externally publishedYes


  • Clark-type electrode
  • Diffusion model
  • Kinetics
  • Nitric oxide
  • Rate constants

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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