TLC chromatography

method

1. wearing gloves, draw a pencil line 1cm above the bottome of the TLC plate and mark spots for each sample, equally spaced along line

2. use a capillary tube to add a tiny drop of each solution to a different spot and allow plate to air dry

3. add solvent to a chamber or large ebacker with a lid so that is no more than 1cm in depth

4. place TLC plate into the chamber making sure that the level of the solvent is bleow the pencil line. replace the lid to get a tight seal

5. when the level of the solvent reaches about 1cm from the top of the plate, remove the plate and mark the solvent level with a pencil

6. allow the plate to dry in the fume cupboard

7. spray the paper with ninhydrdin

8. calculate rf value

wear plastic gloves

prevent contamination from the hands to the plate

pencil line

won’t dissolve in the solvent

tiny drop

too big a drop will cause different spots to merge

depth of solvent

• if solvent is too deep it will dissolve the sample spots from the plate

lid

to prevent evaporation of toxic solvent

why solvent rise 1cm before the top

Will get more accurate results if the solvent is allowed to rise to near the top of the plate but the Rf value can be calculated if the solvent front does not reach the top of the plate

why dry in a fume cupboard

as solvent is toxic

purpose of ninhydrin

to visualise amino acids