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Estimation of the dissociation constants for functional groups on modified and unmodified silica gel supports from the relationship between electroosmotic flow velocity and pH
Author(s) -
Chaiyasut Chaiyavat,
Takatsu Yasuo,
Kitagawa Shinya,
Tsuda Takao
Publication year - 2001
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200105)22:7<1267::aid-elps1267>3.0.co;2-8
Subject(s) - silanol , silica gel , alkyl , chemistry , dissociation (chemistry) , sulfonic acid , ammonium , polyethylene , dissociation constant , acid dissociation constant , inorganic chemistry , chromatography , polymer chemistry , organic chemistry , aqueous solution , catalysis , biochemistry , receptor
Electroosmotic volume flow was directly observed in a simple instrument consisting of 1 cm long a home‐made support, packed between two polyethylene frits in the polypropylene tube. Equations relating electroosmotic flow (EOF) velocity and pH for two functional groups on the surface of the solid materials were developed. With these equations, we can estimate the dissociation constants of two different kinds of functional groups on modified silica gel materials simultaneously. The dissociation constants of silanol groups, benzene sulfonic acid groups, and alkyl quaternary ammonium groups on the modified and unmodified silica gel supports were estimated. The estimated p K values of the silanol groups on the silica gel and modified silica gel surfaces are between 4.0 and 4.3. The estimated p K values of the benzene sulfonic acid groups and alkyl quaternary ammonium groups on the surface of the modified silica gel are 2.6 and 8.6, respectively.