Fabrication of anodically electrodeposited iridium oxide film pH microelectrodes for microenvironmental studies

Achintya N. Bezbaruah, Tian C. Zhang

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A new method for fabrication of anodically electrodeposited iridium oxide film pH microelectrodes has been developed in this study. Novel for its tip size (3-10-μm tip diameter), the microelectrode is fabricated in a tapered glass micropipet filled with a low melting point alloy. The tapered end is recessed and platinized. Thereafter, iridium oxide is electrodeposited over the platinized end in the recessed part. The microelectrode has a very short response time (t80 < 5 s) in the pH range of 0-12 with an accuracy of 0.05 pH unit. The pH microelectrode is not affected by most ions and complexing agents of relevance in environmental and biological studies; it can be used in fluids over wide ranges of stirring speeds (0-55 rpm) and temperatures (∼5-40 °C). Redox agents such as dissolved oxygen and hydrogen peroxide have no effect on the pH response while quinhydrone, ferro- and ferricyanide, and sodium sulfide have marked effects. However, the microelectrode can still be used in any sample when calibration is done in standards having similar redox characteristics.

Original languageEnglish (US)
Pages (from-to)5726-5733
Number of pages8
JournalAnalytical chemistry
Issue number22
StatePublished - Nov 15 2002


ASJC Scopus subject areas

  • Analytical Chemistry

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