Chromotography

• Each pigment has an approximate Rf value
• approximate Rf value of carotene: 0.95
• approximate Rf value of Xanthophyll = 0.71
• approximate Rf value of Chlorophyll A = 0.65
• approximate Rf value of Chlorophyll B = 0.45
• Carotenoids have the highest Rf value (usually closest to 1)
• Chlorophyll B has a much lower Rf value
• Chlorophyll A has an Rf value between that of Chlorophyll B and crotenoids
• Smaller Rf values indicate the pigment is less soluble, and larger
• Rf value = distance travelled by component / distance travelled by solvent
• Chromotography steps:

  1. leaf crushed and juice extracted
  2. chromatography paper strip drawn line at base, mixture from plant concentrated on 1 dot at line
  3. mixture moved up by secondary solvent
  4. components separate as move up to get RF value
• Paper chromatography can be used to identify different components of mixtures such as chloroplast extracts or blood samples.