Amino acids

a) Wearing gloves, draw a pencil line 1 cm above the bottom of a TLC plate and mark spots for each sample, equally spaced along line. b) Use a capillary tube to add a tiny drop of each solution to a different spot and allow the plate to air dry. c) Add solvent to a chamber or large beaker with a lid so that is no more than 1cm in depth d) Place the TLC plate into the chamber, making sure that the level of the solvent is below the pencil line. Replace the lid to get a tight seal. e) When the level of the solvent reaches about 1 cm from the top of the plate, remove the plate and mark the solvent level with a pencil. Allow the plate to dry in the fume cupboard. f) Spray paper with ninhydrin and put in oven Draw around them lightly in pencil. g) Calculate the Rf values of the observed spots.

Wear plastic gloves to prevent contamination from the hands to the plate pencil line –will not dissolve in the solvent tiny drop – too big a drop will cause different spots to merge Depth of solvent– if the solvent is too deep it will dissolve the sample spots from the plate 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 lid– to prevent evaporation of toxic solvent dry in a fume cupboard as the solvent is toxic