Question

Chlorophyll a and chlorophyll b are very closely related structures and you were not able to separate them from each other in this lab by column chromatography. For each of the following variables indicate what specific change, if any, could be made to the procedure to help you separate these compounds during your column chromatography.

Column Length
Column Solid Phase
Extraction Solvents
Elution Solvents
Elution Rate

Answer 1

chrlophyl a and chlorophyl b are green pigments in leaves. column chromatography can uesed to seperate these pigments .example. seperation of chlorophyl pigments from spinach leaves which is rich in these pigments.

procedure: grind and make a paste of spinach leaves , take this extraction mixture in extraction solvent acetone and hexane in 1:1 ratio.filter this extraction solvent and add sodium sulphate inorder to remove the excess water molecules.preapare a column with 25 grams silicagel and elution solvent is hexane again for this experiment.pour the sample extraction volume in th top of column by using pipette, the nonpolar componenets beta ceretonoids elutes first after that, the polar componets chlorophyll a and chlorophyl b will elutes as a single green colour band.this is collected and by using thinlayer chromatography we can findout the Rf values of pingments.

In this experiment the colmn length can be upto 25- 30 cm,

column solid phase is : silicagel packing

extraction solevent: acetone : hexane mixture (1:1 ratio)

elution solvent: hexane ( polar solvent)