required practical 12 - thin layer chromatography

Question 1

method to prepare sample

Answer 1

dissolve small mass of aspiring, anadin, paracetamol, ibuprofen and caffeine with ethanol

Question 2

method of thin layer chromatography

Answer 2

draw pencil line 1cm above bottom of TLC plate
add small drop of each sample
add ethyl acetate to development chamber
place TLC plate in chamber and wait for solvent line to reach near the top
remove plate and leave to dry
place plate under UV or submerge in KMnO4 to visualize the spots
work out Rf value

Question 3

how do you work out Rf value

Answer 3

distance moved by spot/ distance moved by sample

Question 4

why is pencil used to draw the start line

Answer 4

wont dissolve in the solvent or mix with the sample

Question 5

why are small drops used

Answer 5

so they dont merge together

Question 6

why is a lid needed for the development chamber

Answer 6

to prevent evaporation of toxic solvent