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Thin‐Layer Chemical Modulations by a Combined Selective Proton Pump and pH Probe for Direct Alkalinity Detection
Author(s) -
Afshar Majid Ghahraman,
Crespo Gastón A.,
Bakker Eric
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201500797
Subject(s) - alkalinity , titration , chemistry , proton , acid–base titration , membrane , analytical chemistry (journal) , ion , inorganic chemistry , hydrogen , layer (electronics) , electrochemistry , ion pump , chromatography , electrode , organic chemistry , biochemistry , physics , quantum mechanics
We report a general concept based on a selective electrochemical ion pump used for creating concentration perturbations in thin layer samples (∼40 μL). As a first example, hydrogen ions are released from a selective polymeric membrane (proton pump) and the resulting pH is assessed potentiometrically with a second membrane placed directly opposite. By applying a constant potential modulation for 30 s, an induced proton concentration of up to 350 m M may be realized. This concept may become an attractive tool for in situ titrations without the need for sampling, because the thin layer eventually re‐equilibrates with the contacting bulk sample. Acid–base titrations of NaOH and Na 2 CO 3 are demonstrated. The determination of total alkalinity in a river water sample is carried out, giving levels (23.1 m M ) comparable to that obtained by standard methods (23.6 m M ). The concept may be easily extended to other ions (cations, anions, polyions) and may become attractive for environmental and clinical applications.