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Sensitivity and Selectivity of Polypyrrole Based AC‐Amperometric Sensors for Electroinactive Ions – Frequency and Applied Potential Influence
Author(s) -
Walkiewicz Sebastian,
Michalska Agata,
Maksymiuk Krzysztof
Publication year - 2005
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200403227
Subject(s) - polypyrrole , amperometry , selectivity , chemistry , ion , sensitivity (control systems) , inorganic chemistry , environmental chemistry , analytical chemistry (journal) , electrode , electrochemistry , catalysis , organic chemistry , electronic engineering , engineering
Oxidation/reduction of polypyrrole films coupled with ion exchange on the polymer/solution interface can be utilized for amperometric sensing of electroinactive ions. Anion or cation exchanging films (polypyrrole doped by chloride or poly(4‐styrenesulfonate) ions, respectively) can be used to determine common anions (as Cl − , NO $\rm{ {_{3}^{-}}}$ , SO $\rm{ {_{4}^{2-}}}$ etc) or cations (K + , Na + , Li + , Ca 2+ , Mg 2+ ) under conditions of alternating current (AC) amperometry in the range 10 −4 –1 M. A sensitivity can be tuned by choosing appropriate electrode potential, corresponding to polypyrrole oxidation (anion‐exchanging films) or reduction (cation‐exchangers). Electrochemical impedance spectroscopy and AC‐voltammetry studies have shown that applied frequency and potential could also affect the observed dependence of the signal (admittance or AC‐current) on ion concentration. For high frequency the sensitivity is higher but selectivity lower, due to influence of solution conductivity on the response. For low frequencies the sensitivity is lower; however, a selectivity increase was observed due to diverse mobility of ions in the polymer film. Selectivity of AC‐amperometric responses was studied both in separate and mixed solutions.