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What can chromatography be used for?
To separate out and identify biological molecules
What is the mobile phase in chromatography?
Where the molecules can move
What is the mobile phase in paper/thin layer chromatography? Give 2 examples
A liquid solvent e.g ethanol/water
What is the stationary phase in chromatography?
Where the molecules cannot move
What is the stationary phase in paper chromatography?
Chromatography paper
What is the stationary phase in thin layer chromatography?
Thin layer of solid e.g glass
Explain the first step of paper chromatography to separate amino acids
Draw a pencil line near the bottom of the chromatography paper
Put a drop of the concentrated amino acid mixture onto the pencil line
Explain the second step of paper chromatography to separate amino acids
Add a small amount of the solvent to a beaker and place the chromatography paper in it
Cover with a lid to stop the solvent from evaporating
Explain the third step of paper chromatography to separate amino acids
As the solvent spreads up the paper, the different amino acids move with it but at different rates so they will spread out
Explain the fourth step of paper chromatography to separate amino acids
When the solvent has almost reached the top take the chromatography paper out
Mark the solvent front with pencil
Leave the paper to dry
Explain the fifth step of paper chromatography to separate amino acids
Spray the paper with ninhydrin solution to turn the amino acids purple as they’re originally colourless so hard to analyse
Do this in a fume cupboard
What do you use to identify the seperated molecules?
Rf values
Rf value calculation?
distance moved by the solute/distance moved by the solvent