Estimating pH at the air/water interface with a confocal fluorescence microscope

Haiya Yang, Yasushi Imanishi, Akira Harata

    Research output: Contribution to journalArticle

    3 Citations (Scopus)

    Abstract

    One way to determine the pH at the air/water interface with a confocal fluorescence microscope has been proposed. The relation between the pH at the air/water interface and that in a bulk solution has been formulated in connection with the adsorption equilibrium and the dissociation equilibrium of the dye adsorbed. Rhodamine B (RhB) is used as a surface-active fluorescent pH probe. The corrected fluorescence spectrum of RhB molecules at the air/water interface with the surface density of 1.0 nmol m -2 level shows pH-dependent shifts representing an acid-base equilibrium. Two ways to determine the unknown acid-base equilibrium constant of RhB molecules at the air/water interface have been discussed. With surface-tension measurements, the adsorption properties, maximum surface density, and adsorption equilibrium constants were estimated for both cationic and zwitterionic forms of RhB molecules at the air/water interface.

    Original languageEnglish
    Pages (from-to)1005-1010
    Number of pages6
    Journalanalytical sciences
    Volume31
    Issue number10
    DOIs
    Publication statusPublished - 2015

    All Science Journal Classification (ASJC) codes

    • Analytical Chemistry

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