“On line” mass spectrometric detection of ammonia oxidation products generated by polypyrrole based amperometric sensors

Polypyrrole (PPy) is the conducting polymer most widely employed in electrochemical sensors for ammonia detection in the last decade. Although sensors have been described in depth in the literature, the mechanism of ammonia detection by polypyrrole is still a matter of controversy. The differential...

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Bibliographic Details
Published in:Analytica chimica acta 2003-08, Vol.489 (2), p.207-214
Main Authors: Vidotti, Marcio, Dall’Antonia, Luiz H., Córdoba de Torresi, Susana I., Bergamaski, Kleber, Nart, Francisco C.
Format: Article
Language:English
Subjects:
Ammonia detection
Amperometric sensor
Analytical chemistry
Chemistry
DEMS
Electrochemical methods
Exact sciences and technology
General, instrumentation
Polypyrrole
Spectrometric and optical methods
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Summary:Polypyrrole (PPy) is the conducting polymer most widely employed in electrochemical sensors for ammonia detection in the last decade. Although sensors have been described in depth in the literature, the mechanism of ammonia detection by polypyrrole is still a matter of controversy. The differential electrochemical mass spectrometry (DEMS) technique, together with UV-Vis spectroscopy, gives direct and conclusive evidence with respect to the ammonia oxidation products formed in NaOH solution (pH=10) at polyrrole or N-methyl polypyrrole film sensors polarized at 0.35 V (Ag/AgCl). Monitoring of the different possible ammonia oxidation products by on-line DEMS measurements indicates that only NO is formed and that other species such as N 2 or N 2O are absent. UV-Vis absorption spectroscopy also showed that ionic products such as nitrate or nitrite are not formed.
ISSN:0003-2670
1873-4324
DOI:10.1016/S0003-2670(03)00757-8