| Capillary electrophoresis is a technique capable of high separation efficiency, good resolution, and fast migration times due in part to the electroosmotic flow (EOF). However, separations can be hampered by adsorption of analytes to the capillary wall especially in the case of biomolecules. This thesis examines means of enhancing and suppressing the EOF, and of preventing protein adsorption.;As these additives are not overly effective at preventing protein adsorption, a novel coating was developed for this purpose. The coating consists of a double-chain cationic surfactant bilayer of dioctadecyldimethylammonium bromide (DODAB) in direct contact with the capillary wall and an intercalated diblock copolymer, polyoxyethylene (POE) stearate. The POE moieties protrude into the surrounding solution resulting in a neutral hydrophilic surface. Efficiencies up to 1.3 million plates/m are achieved using this coating with protein recoveries of 84--97% for basic and acidic proteins.;A modified coating method imparts greater stability with RSDs of migration times <0.5% over 28 consecutive runs with no recoating between runs. Polymer concentration and chain length are varied to produce a tunable coating. The EOF can also be tuned from -1.2 x 10-4cm2/Vs to -0.4 x 10-4cm2/Vs using mixtures of POE 40 stearate and POE 8 stearate on a DODAB coated capillary.;Band broadening sources other than adsorption are studied using the DODAB/POE stearate coating. Protein peak efficiencies and asymmetries improve with increasing buffer concentration. Buffer co-ion and low protein concentration also enhance these parameters in a manner consistent with a decrease in electromigration dispersion. Similar observations are noted on a commercially available polyvinyl alcohol (PVA) coating.;The effect of a series of zwitterionic additives on the EOF is studied. The structures of the additives are found to have an effect on the overall EOF enhancement with the order of the amine headgroup and intercharge distance between the ionic functionalities having the largest influence. An EOF enhancement of 63% is noted with the highest order amine, Z1-Methyl, while a 70% enhancement is noted with the longest carbon chain additive, 8-aminocaprylic acid. |
