Paper Chromatography

Question 1

Explain the basic steps to using chromatography to identify a biological molecule

Answer 1

1) draw a pencil line near the bottom of a piece of chromatography paper and put a concentrated spot of the mixture on it
2) add a small amount of prepared solvent to a beaker and dip the bottom of the paper into it ensuring it doesn’t cover the spot. Cover with a lid to stop solvent evaporating
3) as the solvent spreads up the paper, the solutes move up with it but at different rates, so they separate out
4) when the solvent is almost at the top take the paper out and mark the solvent front with s pencil. Then you can leave the paper to dry out before you analyse it
5) then use Rf values to identify the separated molecules

Question 2

What is the equation for calculating the Rf value

Answer 2

Rf value = distance travelled by solute
distance travelled by solvent