tailieunhanh - Introduction to Separations Science

IUPAC Definition: chromatography is a physical method of separation in which the components to be separated are distributed between two phases, one of which is stationary while the other moves in a definite direction Stationary phase (SP): common name for the column packing material in any type of chromatography Mobile phase (MP): liquid media that continuously flows through the column and carries the analytes Analyte: the chemical species being investigated (detected and quantitatively measured) by an analytical method. | a W VILLANOVA UNIVERSITY Introduction to Separations Science Lecture Date March 31st 2008 Introduction to Separations Science What is separations science - A collection of techniques for separating complex mixtures of analytes - Most separations are not an analytical technique in their own right until combined with an analytical detector often a type of spectrometer Key analytical branches chromatography electrophoresis extraction Reading - Skoog et al. Chapter 26 1 What is a Separation Separations are key aspects of many modern analytical methods. Real world samples contain many analytes most analytical methods do not offer sufficient selectivity to be able to speciate all the analytes that might be present. Most separation methods involve separation of the analytes into distinct chemical species followed by detection a b c d . a b c d . a b c d . a b c d . COMPLETE SEPARATION a b c d . 1 PARTIAL SEPARATION a b b a . ENRICHMENT Basic Types of Separations Liquid Column Chromatogrphy Liquid- Liquid partition chromatography LLC stationary and mobile phases immiscible Liquid -Solid adsorption chromatography LSC Ion exchange chromatography IEC Exclusion chromatography EC Gas-Liquid chromatography GLC Gas-Solid chromatography GSC Separation Methods Based on Phase Equilibria Gas-LiquidGas-Solid Distillation Sublimation Foam Fractionation Liquid-Liquid Liquid-Solid Adsorption Extraction Precipitation chrom Gas- Liquid Liq-Liq Chrom Zone melting Molecular sieves Exclusion Fractional crystallization Ion Exchange Adsorption Exclusion Molecular sieves 2 Basic Types of Separations Separation methods based on rate processes Barrier Separation membrane filtration dialysis electro-dialysis electro-osmosis reverse osmosis gaseous diffusion Field Separations electrophoresis ultracentrifugation thermal diffusion electrodeposition mass spectrometry Other molecular distillation enzyme degradation destructive distillation Particle Separation methods Filtration .