| Enhanced-fluidity liquids are mixtures of common liquids such as methanol, water combined with large proportions of a liquefied gas such as carbon dioxide (CO2). These mixtures retain solvent strength similar to that of common liquids, while the addition of high proportions of the liquefied gas decreases the viscosity substantially. These properties provide improvements to high performance liquid chromatography (HPLC) such as increased efficiency, speed of analysis, lower pressure drop and tunable solvent strength.;To date, CO2 has been used as the predominant fluidity-enhancing agent. However, the intrinsic limitations of CO2, including formation of carbonic acid with water, reaction with some basic compounds and very limited solvating power, prevented EFLC from a wider application range.;In this dissertation, fluoroform (CHF3) was thoroughly investigated as a fluidity-enhancing agent for the first time. Fluoroform was chosen due to its high polarity, low viscosity and chemical inertness. Fundamental properties of methanol/CHF3 and methanol/H2O/CHF3 mixtures were characterized. Phase diagrams were determined using a high pressure, variable-volume view cell at temperature of 25--100°C and pressure of atmospheric to 340 atm. Solvatochromic solvent strength parameters were measured with UV/Vis spectroscopy at temperature of 24°C and pressure of 170 atm.;Applications of EFLC using CHF3 were demonstrated in the separations of a range of basic and strongly polar compounds including anilines and tricyclic antidepressants. Reversed-phase separations using buffered mobile phases with and without CHF3 addition were compared. The advantages of buffered and CHF3-enhanced liquid mobile phases were shown in the improved chromatographic performance, such as improved speed of analysis, increased efficiency and lower pressure drop.;Furthermore, this study demonstrated for the first time, that commercial SFC instruments could be used for EFLC and HPLC separations, greatly expanding the application range of the EFLC technique and chromatographic instrumentation. Finally, the utility and potential of the EFLC technique were explored in solving a real-world separation problem. A fast and efficient EFLC method was developed for the separation of commercial dimer and trimer acids. |
