COLUMN CHROMATOGRAPHY(CC)

TLC - Optimizing for column chromatography

Optimum: 0.2 < Rf < 0.5

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

COLUMN CHROMATOGRAPHY

Skoog and Leary: Principals of Instrumental Analysis, 4 th ed. Suanders, 1992

FLASH COLUMN CHROMATOGRAPHY

FLASH COLUMN CHROMATOGRAPHY

• Build column• Apply sample• Elute • Collect Fractions• Analyze by TLC• Combine pure fractions

FLASH COLUMN CHROMATOGRAPHY

FCC - OPTIMIZATION

Measure of column efficiency

FCC – Sample vs Column Size

TLC vs High Performance Liquid Chromatography (HPLC)

http://www.labhut.com/education/flash/introduction07.php

TLC vs High Performance Liquid Chromatography (HPLC)