High-performance capillary gel electrochromatography with replaceable media

Capillary gel electrochromatography is evaluated with an entangled polymer solution which is pumped into the capillary and run under fritless conditions. The polymer used has an acid backbone with grafted hydrophobic segments, the polyacid giving the electroosmotic flow and the hydrophobe segments providing the retentive component. Experimental evaluation of this type of system reveals performance similar to capillary electrophoresis and other forms of electrochromatography. The analysis of plate height data demonstrates that zone broadening is primarily due to diffusion with little contribution from nonequilibrium zone broadening. Hence, operation at high velocities (high voltages) is most desirable as opposed to most chromatographic methods. Some of the advantages of this type of experiment include being able to replace the retentive media in a few minutes, fast and reproducible high-performance separation, and having a retention mechanism similar to reversed-phase liquid chromatography. Disadvantages include a low retentive phase concentration and hence low sample loadability and limited solvent compatibility of the polymer. A number of different separations are demonstrated including separation of alkyl benzoates, alkylphenones, alkylbenzenes, oxidation inhibitors, and PAHs.