Development and applications of electrically driven separation methods.

Capillary Electrochromatography (CEC) is one of the newest separation techniques. It is a hybrid technique of high performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE). It combines the simplest capillary electrophoresis mode where separations are based on the differences in the electrophoretic migration of charged analytes under the influence of a high electric field with separation based on analyte partitioning between the mobile phase and stationery phase from liquid chromatography. Mass spectrometry (MS), which requires ionized analytes in order to be detected, is an ideal detection technique for CZE. It is also a sensitive, selective and universal detector. However, CZE-MS interfacing is difficult. It is crucial to maintain a stable electrical contact throughout the CE capillary and ion-source as well as adequate grounding of the high voltage applied in CE. The main practical problem is the great mismatch in flow rates through the CE capillary and the solvent flow required for the general LC-MS ion-sources, such as electrospray. Thus, the evaluation of the interfacing is also reported.The CEC work presented in this thesis details the examination of effects of physicochemical properties of different silica based C18 stationary phases on their chromatographic performance in CEC separations for a series of different acidic, neutral and basic type of analytes. In the other half of this thesis, the application of a fast electrophoretic separation to improve previous HPLC separation and mass spectrometric detection of surfactants with great importance in oil recovery is reported. The surfactants, commercial nonylphenol ethoxysulphates (NEPOSp) and sulphonates (NEPOS), have been separated by reversed type CZE and the surfactants were also analysed then by mass spectrometric detection on a triple quadruple mass spectrometer using home-built co-axial sheath flow electrospray interfaces. The obtained data indicates that reverse mode CZE provided faster separation with the same ethoxymer resolution than HPLC, while the calculated average number of ethoxymer units in the surfactants formulations (6.46 for NPEOS and 6.45 for NPEOSp) were in good agreement with previous data obtained in our group by different methods.