Preparing of Iridium Oxide Film Modified Microelectrode as an Amperometric Detector in FIA for Determination of Epinephrine

Abstract

Iridium oxide film modified microelectrode with a tip diameter of 25 µm was constructed using anodically grown iridium oxide film. The iridium oxide film, which was formed at the tip of the iridium wire by cyclic voltammetry in dilute sulfuric acid, showed excellent catalytic activity towards the oxidation of epinephrine. The stability and electrochemical properties of iridium oxide film modified microelectrode along with catalytic oxidation of epinephrine was studied. An oxidation peak was observed at 0.28 V. The electron‐transfer number (n) was 2. The iridium oxide film modified microelectrode was used as a detector in flow injection system for determination of epinephrine. Under the optimized conditions, the calibration curve was linear in the concentration range of 1.0×10⁻⁸ to 1.0×10⁻⁵ mol/l for epinephrine, with a detection limit of 1.0×10⁻⁹ mol/l. The iridium oxide film modified microelectrode was used for direct determination of the epinephrine in human serum samples. The flow injection analysis was precise detection method of epinephrine and time saving device.

Keywords:

• Iridium oxide
• epinephrine
• modified microelectrode
• flow injection
• serum

The authors gratefully acknowledge financial support by the National Science Foundation of China (No. 20665003), the Nature Science Foundation of Guangxi Province (No. 0679002) and the program for 100 Young and Middle‐aged Disciplinary Leaders in Guangxi Higher Education Institutions (No. [2005]64).