Required practical 12 Flashcards
Preparation - 1
Crush an aspirin tablet with a pestle and mortar
Preparation - 2
Transfer to weighing boat
Preparation - 3
Dissolve approx 0.1g tablet in 0.5cm ethanol
Preparation - 4
Repeat with the other tablets
TLC - 1
Wearing gloves, carefully draw a pencil line about 1cm from the bottom of the TLC plate and mark 5 spots across it
Explanation of step 1
Gloves prevent the contamination from hands to plate
Pencil line will not dissolve in the solvent
TLC - 2
Use a capillary tube to add a tiny drop of each solution to different origin spots on the line and leave to air dry
Explanation of step 2
The dots should be tiny as if they are too big they will merge
TLC - 3
Add approximately 10cm^3 solvent to a beaker
Explanation of step 3
Must not add to much solvent - must be below the pencil line or the spots will dissolve
TLC - 4
Add the TLC plate to the beaker and add a watch glass to the top
Explanation of step 4
Lid prevents the evaporation of toxic solvent
TLC - 5
When the solvent reaches about 1cm from the top of the plate, remove the plate and mark the solvent front with a pencil - allow to dry in the fume cupboard
Explanation of step 5
More accurate results if the solvent is higher up the plate as there is more chance for separation.
Dry in the fume cupboard as the solvent is toxic
TLC - 6
Place the plate under UV light to visualise the spots and draw around them lightly in pencil
