ChromatographySeparating plant pigments

Cellulose Paper (stationary phase)

Ethanol Solvent (mobile phase)

Chromatography

• It is possible to measure the solubility of a pigment in a solvent by measuring how far the pigment travels vs. how far the solvent travels• This is called retention factor, or Rf value• Rf values are characteristic of specific pigments and can be used to

identify them• The higher the Rf value, the less polar the compound. • Thus, a compound not migrating from the origin would have an Rf of

0, a compound migrating with the solvent front would have an Rf of 1.0, and a compound migrating half as far as the solvent front would have an Rf of 0.5.

Plant Pigments

Rf values of pigments

• Carotene - 0.98; orange • Pheophytin - 0.81; olive green • Chlorophyll a - 0.59; blue-green • Chlorophyll b - 0.42; yellow-green • Anthocyanins - between 0.32 and 0.62; red, pink, purple and blue

colors • Xanthophyll 1 - 0.28, yellow • Xanthophyll 2 - 0.15, yellow