TLC - Optimizing for column chromatography Optimum: 0.2 < Rf < 0.5
COLUMN CHROMATOGRAPHY Column chromatography (CC) is an extremely valuable technique for purification of synthetic or natural products. Compounds are separated by CC through the same mechanism as TLC; through differential intermolecular forces between the components of the mixture with the mobile phase, and between the components with the stationary phase. A variety of adsorbents can be used as the stationary phase; silica gel (which is very polar) is most commonly used in organic chemistry.
COLUMN CHROMATOGRAPHY Polar components (b) adsorb more strongly to the polar silica and elute after the less polar components (a), which move more quickly with the non-polar (relative to silica) solvent.
COLUMN CHROMATOGRAPHY Skoog and Leary: Principals of Instrumental Analysis, 4th ed. Suanders, 1992
FLASH COLUMN CHROMATOGRAPHY • Build column • Apply sample • Elute • Collect Fractions • Analyze by TLC • Combine pure fractions
FCC - OPTIMIZATION Measure of column efficiency
TLC vs High Performance Liquid Chromatography (HPLC) http://www.labhut.com/education/flash/introduction07.php