Published:Journal of Chromatographic Science,
ISSN 0021-9665Volume
40, Number 4, April, pp. 187-190
The Surface Properties of Tetradecyltrimethylammonium Bromide
Observed by Capillary Electrophoresis
David L. Cocke*, R. Schennach,
and Zhenhao Yu
Gill Chair of Chemistry and Chemical Engineering, Lamar University, Beaumont,
TX 77710
The electroosmotic flow (EOF) is measured as a function of tetradecyltrimethylammonium
bromide (TTAB) concentration and is shown to have distinct zones that are pH
dependent. The data is correlated with previously proposed surface structures
ranging from unimolecular adsorption to hemimicelles and micelles of TTAB adsorbed
on the hydrated fused silica. A plot of the TTAB concentration at zero EOF versus
pH shows that the zero point of charge (zpc) is pH dependent and that a linear
extrapolation of the data intercepts close to the pH value for the zpc of a
fused-silica surface. This shows that different surface properties at different
pH values at any given TTAB concentration are generally dealt with. Therefore,
these pH-dependent structures of the fused-silica surface have to be taken into
account while studying these phenomena.
Reproduction
of editorial content of this journal is prohibited without publisher’s
permission.
This
article is available in its entirety by fax for $4.00 per
page.
Visa or MasterCard accepted.
To
order electronicallyclick here or call: 847-647-2900 ext. 1323 or fax request to: 847-647-1155.
Please
indicate JCS volume and issue along with
page numbers.
