| Abstract
| - Polyacrylamide has been used for capillary wall coatingfor decades. The coating chemistry includes two mainsteps: (i) attachment of a bifunctional reagent containinga vinyl group to the silica surface and (ii) extension of theanchored vinyl groups through acrylamide polymerization.Since the introduction of this method, many modificationsand improvements have been made. However, few of themare successful for routine capillary isoelectric focusing.One of the major problems is the presence of somemicrospots in which the silica surfaces are poorly coated.Cross-linking the polyacrylamide molecules anchoredaround these poorly coated spots seems to be a straightforward solution to this problem. Attempts have beenmade toward this direction, but cross-linked polyacrylamide coatings have not been demonstrated to be muchsuperior over linear polyacrylamide ones. In this report,we have reexamined this approach and demonstrated thatcross-linked polyacrylamide could be excellent for capillary isoelectric focusing. A simple device and a newcoating protocol have been developed to produce thiscoating reliably and reproducibly. Compared to the commercial linear polyacrylamide and hydroxypropyl cellulosecoatings for CIEF, the cross-linked polyacrylamide coatingis much more stable and robust although their initialperformances are comparable.
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