PVA coated capillaries contain a permanently adsorbed layer of polyvinyl alcohol. This coating minimises hydrophobic and electrostatic solute/wall interactions and eliminates electroosmotic flow (EOF). Using a proprietary deposition process, the PVA coating is stable over a wide pHrange, even under basic conditions from 2,5 to 9,5. This stability allows the use of many common CE buffers. Because the silica surface is covered, many proteins and amines can be analysed without the peak tailing found with uncoated capillaries. In addition, since EOF is eliminated, cumbersome washing procedures are unnecessary and migration time reproducibility may be improved.
The colour coding of the capillary (alignment stopper) and the alignment interfaces makes it easy to combine the correct interface with the capillary. Capillaries for non-Agilent CE systems have removable alignment stoppers without colour code.
PVA coated capillaries can be used for a variety of applications, including protein analysis at physiological pH, isoelectric focusing, and small anion analysis without the need for flow-reversal agents in the buffer.
PVA coating is available in standard capillaries, or in Agilent Extended Light Path Capillaries ("bubble" cell capillaries) for high sensitivity applications. Both capillary types are available in longer lengths for use in non-Agilent systems.
Note 1: Not compatible with borate buffers
Note 2: PVA coated capillaries for CE/MS have a blue alignment stopper matching the blue colour code of the alignment interface for MS-UV detection. The alignment stopper of the 50 μm ID PVA capillary for CE/MS has a black dot for easy identification.
Note 3: When extended pathlength capillaries are used in non-Agilent systems, loss of resolution may be found if the axial slit width is not reduced. In Agilent systems, the alignment interface contains properly matched slits to maintain resolution.