Chromatography

Question 1

Is it essential to wear plastic gloves to hold a TLC plate? Why?

Answer 1

Essential – to prevent contamination from the hands to the plate

Question 2

Is it essential to add developing solvent to a depth of not more than 1 cm^3 if pencil line is 1.5 cm^3 height?

Answer 2

Essential – if the solvent is too deep it will dissolve the mixture from
the plate

Question 3

Outline the steps needed to locate the components on the TLC plate and to determine their Rf values

Answer 3

• Spray with developing agent or use UV
• Measure distances from initial pencil line to the spots (x)
• Measure distance from initial pencil line to solvent front line (y)
• Rf value = x / y

Question 4

Explain why different amino acids have different Rf values

Answer 4

Amino acids have different polarities. Therefore, have different retention on the stationary phase or different
solubility in the developing solvent