Nitrogen Oxide Gas Sensor Based on a Nitrite-Selective Electrode

Stacy A. O’Reilly, Sylvia Daunert, Leonidas G. Bachas

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Abstract

Incorporation of dicyanocobalt(III) a,b,c,d,e,f,g-heptapropylcobyrinete in plasticized poly(vinyl chloride) membranes has resulted in the development of electrodes that are selective for nitrite. An NOx gas sensor was prepared by placing this electrode behind a microporous gas-permeable membrane. NOx is generated in the sample at pH 1.7 and, after crossing the gas-permeable membrane, is trapped as nitrite by an internal solution buffered at pH ≥ 5.5. This sensor is different from the conventional Severlnghaus-type sensor, which employs a flat-bottom pH electrode. The latter senses changes in the pH of an internal unbuffered solution as NOx diffuses across the gas-permeable membrane. The Severinghaus-type sensor exhibits severe interferences from weak lipophilic acids that can cross the gas-permeable membrane and affect the pH of the internal solution. The described NOx sensor does not suffer from such interferences and exhibits better detection limits.

Original languageEnglish (US)
Pages (from-to)1278-1281
Number of pages4
JournalAnalytical Chemistry
Volume63
Issue number13
DOIs
StatePublished - Jul 1 1991

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ASJC Scopus subject areas

  • Analytical Chemistry

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