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Poly(tetrafluoroethylene) separation capillaries for capillary electrophoresis - Properties and applications

Citation

Macka, M and Yang, W and Zakaria, P and Shitangkoon, A and Hilder, EF and Andersson, PE and Nesterenko, PN and Haddad, PR, Poly(tetrafluoroethylene) separation capillaries for capillary electrophoresis - Properties and applications, Journal of Chromatography A, 1039, (1-2) pp. 193-199. ISSN 0021-9673 (2004) [Refereed Article]

DOI: doi:10.1016/j.chroma.2004.03.074

Abstract

Poly(tetrafluoroethylene) (PTFE) is a material widely known for its inertness and excellent electrical properties. It is also transparent in the UV region and has a reasonable thermal conductivity. These properties make PTFE a suitable material for the separation capillary in capillary electrophoresis. Differences in the chemistry of the capillary wall compared to fused silica (FS) can make PTFE an interesting alternative to FS for some special applications. In this work, properties of a commercial PTFE capillary of approx. 100 μm i.d. were investigated, including the dependence of electroosmotic flow (EOF) on pH for unmodified and dynamically modified PTFE, optical properties, and practical aspects of use. The main problems encountered for the particular PTFE capillary used in this study were that it was mechanically too soft for routine usage and the crystallinity of the PTFE caused light scattering, leading to high background absorbance values in the low UV region. The profile of the EOF versus pH for bare PTFE surprisingly showed significantly negative EOF values at pH <4.2, with an EOF of -30×10-9 m2 V -1 s-1 being observed at pH 2.5. This is likely to be caused by either impurities or additives of basic character in the PTFE, so that after their protonation at acidic pH they establish a positive charge on the capillary wall and create a negative EOF. A stable cationic semi-permanent coating of poly(diallyldimethylammonium chloride) (PDDAC) could be established on the PTFE capillary and led to very similar magnitudes of EOF to those observed with FS. A hexadecanesulfonate coating produced a cathodic EOF of extremely high magnitude ranging between +90 and +110×10-9 m2 s-1 V-1, which are values high enough to allow counter-EOF separation of high mobility inorganic anions. In addition, pH-independent micellar electrokinetic capillary chromatography (MEKC) separations could be easily realised due to hydrophobic adsorption of sodium dodecylsulfate (used to form the micelles) on the wall of the PTFE capillary. The use of polymers that would be mechanically more robust and optically transparent in the low-UV region should make such CE capillaries an interesting alternative to fused silica. © 2004 Elsevier B.V. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Chemical Sciences
Research Group:Analytical Chemistry
Research Field:Separation Science
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
Author:Macka, M (Professor Mirek Macka)
Author:Yang, W (Mr Wen-Chu Yang)
Author:Zakaria, P (Dr Philip Zakaria)
Author:Hilder, EF (Professor Emily Hilder)
Author:Andersson, PE (Dr Andersson)
Author:Nesterenko, PN (Professor Pavel Nesterenko)
Author:Haddad, PR (Professor Paul Haddad)
ID Code:31933
Year Published:2004
Web of Science® Times Cited:17
Deposited By:Chemistry
Deposited On:2004-08-01
Last Modified:2009-08-13
Downloads:0

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