NAMS 2002 Workshop - ICOM 2008

Hybrid and Novel Processes II – 5
Thursday July 17, 4:30 PM-5:00 PM, Kaua’i
Capillary ElectroChromatography and Membrane Technology: Merging the
Advantages
K. Kopec (Speaker), University of Twente, The Netherlands
D. Stamatialis, University of Twente, The Netherlands - d.stamatialis@utwente.nl
M. Wessling, University of Twente, The Netherlands
Introduction
Capillary ElectroChromatography (CEC) is a separation technique that is a hybrid
of capillary electrophoresis (CE) and high performance liquid chromatography
(HPLC). The flow of mobile phase is driven through the column by an electric
field (a phenomenon known as electroosmosis) generated by applying a high
voltage across the column. Application of electrical current, rather than pressure,
and presence of a stationary phase result together in fast separations that
combine the efficiency of capillary electrophoresis and the selectivity of liquid
chromatography. CEC with its precision, accuracy and possibility of separation of
complex mixtures is an eligible technique for dealing with biomolecules (proteins,
peptides) and pharmaceuticals. Currently three types of columns are used in
capillary electrochromatography: in-situ polymerized monoliths, capillaries
packed with particles and capillaries with inner coatings (open tubular). In each
case, the stationary phase is incorporated into fused silica capillary and in each
case manufacture of a CEC column is a time consuming and expensive process.
Experimental
In our approach, membrane technology is employed to produce porous polymer
fibers and apply them as stationary phase in CEC. Full, as well as, small borefibers,
both with uniform porosities are manufactured via phase inversion by
immersion precipitation spinning. In this work, fibres are prepared from two
different blends: poly-ether-sulphone (PES) with sulphonated poly-ether-etherketone
(S-PEEK), and polyimide P84 with S-PEEK. The sulphonation degree of
S-PEEK and the blend ratios of PES/S- PEEK and P84/S-PEEK are tailored to
achieve fibre with high charge density and mechanical stability. The sulphonic
functional groups of S-PEEK, which are ionized over a wide range of pH,
generate high electroosmotic flow.
Results and conclusions
The produced fibres have outer diameters ranging from 400 to 1000 micron,
small bores up to 60 micron and sizes of the pores from 0.5 to 15 micron. The