Autotrophs, organisms that produce their own food, utilize certain pigments to carry out photosynthesis. The most important of these is chlorophyll a, for it passes the energized electrons to the molecules that produce glucose. Seventy-five percent of chlorophyll in green plants is chlorophyll a. Chlorophyll a is green.
Chlorophyll b is also an important type of chlorophyll, but unlike chlorophyll a, it is not vital to photosynthesis. Chlorophyll b is found in green algae and certain plants, it is yellow green. Chlorophyll b absorbs light of a different wavelength than chlorophyll a, but ultimately transfers it to chlorophyll a for conversion into chemical energy.
Chromatography is a technique used to separate mixtures of compounds. There are many different types of Chromatography, including: paper chromatography, ion concentration chromatography, gas-liquid chromatography, thin layer chromatography, partition chromatography and gel-permeation chromatography. .
Chromatography consists of two phases: the stationary phase and the mobile phase. The stationary phase consists of a stationary item which allows the molecules to pass through at different times, based on their size. The mobile phase is the solvent which dissolves the substance being tested. .
Paper chromatography uses sheets of paper as the absorbent stationary phase, acetone is commonly used for the mobile phase. Some of the pigments dissolve quicker than others, which causes them to move up the paper through capillary action into different areas. This separation allows the different pigments to be identified while on the paper through color identification. .
Aim: To observe the chromatography process of chlorophyll and calculate Rf values of the different pigments separated.
- Chromatogram jar .
- Chromatography paper .
- Spinach leaves .
1. Grind fresh spinach leaves in a mortar with pure acetone. Filter the mixture and keep the chlorophyll filtrate in an open beaker to evaporate the acetone and concentrate the pigments.