Re: How can you obtain chlorophyll from a leaf?

The basic answer is to grind up the leaf in some kind of organic solvent,
and then to remove any undissolved bits by filtering or centrifugation.

The standard solvent is made of 80 % propanone ('acetone') and 20 %
 water, both measured by volume. Other solvents, such as ethanol ('ethyl
 alcohol') will also do the trick. Leaves ground up in a mortar & pestle with
 this solvent added will release chlorophyll into the solvent, and you can
 then remove the solid leaf bits to obtain a fairly pure chlorophyll solution.

There will be some contaminants, notably other pigments such as
 carotenes and xanthophylls, but these are usually minor. You can check
 for these by chromatography.

Pure chlorophyll is unstable and needs to be kept out of the light. Even so,
it will not keep for long.

If anyone's interested, the method was first published in:
Arnon, DI (1949) Copper enzymes in isolated chloroplasts. Polyphenoloxidase in Beta vulgaris. Plant Physiol. 24:1-15