| Chiral separation by liquid chromatography using chiral stationary phases is the most popular approach in industry. In this dissertation, a series of coumarin related compounds is analyzed using a packed capillary beta-cyclodextrin column with on-column laser-induced fluorescence detection.; In our approach for data analysis, the exponential modified Gaussian (EMG) model is employed. In order to validate this model, a three-dimensional stochastic simulation is first performed. Five methods are applied to extract the thermodynamic and kinetic information: "true" method, Statistical moment method, EMG method, Thomas method and Giddings method. Comparison of the accuracy relative to the "true" retention factors and "true" rate constants demonstrates that the EMG model provides similar results to the other models.; The experimental data are examined with the EMG model to observe the effect of mobile phase composition, temperature and pressure on the thermodynamics and kinetics of chiral separation. A polar-organic mobile phase composed of acetonitrile, methanol, acetic acid, and triethylamine is utilized.; Mobile phase composition affects the equilibration time, isotherm, retention, chiral selectivity, as well as the kinetic rate constants of the chiral separation. Both acid and amine modifiers can help to shorten the equilibration time greatly. Acid modifier increases the linear isotherm range but decreases chiral selectivity. Amine modifier decreases retention and benefits chiral selectivity. Methanol decreases retention by hydrogen bonding. The mass transfer rate constant usually increases as the retention decreases. However, the second enantiomer often has a surprisingly faster mass transfer rate than the first enantiomer although it is more retained.; Temperature and pressure also affect retention, chiral selectivity, and kinetic rate constants. Temperature decreases retention and chiral selectivity for all compounds. Pressure decreases retention but does not significantly affect chiral selectivity. The changes in molar enthalpy are negative for all compounds, indicating an energetically favorable transfer from mobile to stationary phase. The changes in molar volume are positive for all compounds, indicating the compounds occupy more space in the stationary phase than in the mobile phase. No enthalpy-entropy compensation is achieved, hence different retention mechanisms are responsible for each compound.; In addition to chiral separation, a series of nitrogen-containing polycyclic aromatic hydrocarbons (N-PAHs) are investigated in a similar manner to observe the effects of mobile phase composition, temperature and pressure on an octadecylsilica column. The results demonstrate that the partition mechanism is dominant in methanol mobile phase but the adsorption mechanism is dominant in acetonitrile mobile phase. Another technique, fluorescence quenching, is also utilized to differentiate different types of N-PAHs with aliphatic amine quenchers. Aliphatic amines can selectively quench aza-PAHs over amino-PAHs. |
