Novel and functional stationary phase for capillary electrochromatography

Capillary electrochromatography (CEC) is a hybrid microseparation technique that combines electrophoretic and chromatographic separation principle. CEC has not yet found wide acceptance as a practical tool in the chromatographic community. This narrow currency of CEC is mainly attributed to two factors: 1) much fewer examples of real sample analysis by CEC than those by HPLC; 2) a limited variation of the stationay phase specially designed for CEC. In this thesis, CEC with NAIP, 3-(1,8-naphthalimido) propyl-modified silyl silica gel, demonstrated suitability for the prompt screening of toxic drugs and the expeditious analysis of microdialysate. Good repeatability of the proposed method with a durable NAIP column was proved to be sufficient for real sample analysis. Moreover, SNAIP, 3-(4-sulfo-1,8-naphthal-imido) propyl-modified silyl silica gel, was specially designed as a CEC stationary phase and, as expected, the sulfonic acid group in SNAIP worked as a strong EOF generator. In addition to hydrophobic and pi-pi interactions, an electrostatic interaction participated in the retention mechanism of SNAIP. This multiple retentive mechanism indicated an advantage in the separation of peptides, which are difficult to be separated solely based on a hydrophobic interaction, and to be eluted early without high buffer concentration. The remarkable tolerance of current in CEC with SNAIP accomplished the purpose that a high concentration of buffer in mobile phase could be used for the accelerated elution of multiple charged peptides. The tolerance also enabled the use of a highly aqueous mobile phase for the separation of polar nucleosides and nucleic acid bases on a SNAIP column.