超臨界流體萃取及層析-AcademiaSinicaAgricultural.ppt

超臨界流體萃取,層析及其他應用 Supercritical Fluid Extraction, Chromatography and Other Applications 林華經 引光生物科技有限公司 What is a Supercritical Fluid ? When the pressure and temperature of a substance is raised above its critical pressure and critical temperature (the critical point) the substance enters the supercritical state. A Supercritical Fluid is a substance with both gas- and liquid-like properties. Critical Temperature and Pressure The Critical Temperature (Tc) is the maximum temperature at which a gas can be converted to a liquid by increasing the pressure. The Critical Pressure (Pc) is the maximum pressure at which a liquid can be converted to a gas by increasing the temperature. Phase Diagram of Carbon Dioxide Physical Properties of CO2 Advantages of Supercritical Fluids as solvents Solvating power related to density (at constant T) Gas-like mass transport properties Facile penetration into porous material Critical Parameters of Common Fluids Advantages of CO2 for SFE Low critical parameters Inert, Non-toxic, Nonflammable, Non-corrosive Easily purified (inexpensive) Nonpolar: dielectric constant similar to hexane Modifiers can be used to increase polarity Supercritical Fluid Extraction (SFE) Basic Theory SFE System Components Advantages of SFE over Solvent Extraction Faster Results in minutes rather than hours Selectivity results in cleaner extracts Low Critical Parameters Handling of thermally labile analytes Non-hazardous solvents Automated Cost per test is lower Limited or no solvent removal required No solvent disposal costs The Mechanism of SFE A Three Step Process Dissolving/Resolving analyte(s) 2. Sweeping the analyte(s) from the matrix 3. Trapping the analyte(s) SFE Mechanism Trapping SFE - Method Development Pressure Increase pressure increases density = increase in solubilizing power. Temperature Increase temperature may decreases density = decrease in solubilizing power (ie CO2 at 100 bar) Extraction Time Flow Rate Fluid Composition Co