University:
Winston-Salem Forsyth County Schools
Course:
AP Physics I
Academic year:

2013
Views:

78

Pages:

12
Author:

Lepeactiott5mxm

Principles of Chromatography Process by which one separate compounds from one another by passing a mixture through a column that retains some compounds longer than others. Chromatography Eluent Eluate Column In Out Mobile phase = solvent moving through the column. Stationary phase = substance that stays fixed inside the column. Eluent = fluid entering the column. Eluate = fluid exiting the column. Gas Chromatography = gas carrier Liquid Chromatography = liquid mobile phase Types of Chromatography How We Describe a Chromatogram? Chromatographic Separations Planar Column Gas Chromatography Column separation (gas-liquid, gas-solid) used for separating and analyzing compounds that can be vaporized without decomposition. Separations based on differences in boiling points! Liquid Chromatography Column separation (liquid-liquid, liquid-solid) used for separating and analyzing compounds based on differences in their interaction with a stationary phase. Adsorption, partition, ion exchange, molecular exclusion and affinity Gas and Liquid Chromatography Why Do Bands Separate and Broaden with Time on Column? Efficiency of Separation H = L/N Small plate height = narrow peaks = better separation Multiple Flow Path Term Zone Broadening Terms A term = Eddy Diffusion Bterm = Longitudinal Diffusion C term = Stationary Phase Mass Transport Why Do We Care About Flow Rate? N (efficiency) = L/H N α Rs Van Deemter Eq. Flow Velocity (cm/s) = Flow Rate (cm3/s)/Cross sectional area (cm2)