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Paper chromatography of amino acids

This is a description of how to use paper chromatography of amino acids (to identify amino acids).

Table of contents
1 Aims
2 Materials
3 Methods
4 Hazards
5 See also

Aims

Materials

Methods

BAW solvent should be made up fresh on the day.
Using a pencil, lightly draw a line 1.5 – 2cm above the bottom of the chromatography paper. Make small marks at 1.5cm intervals along the line. Fill a capillary tube or pipette by capillary action with your first sample. Touch the tip of the capillary to the first mark and pull it away. You should leave a small (>5mm) wet spot. Let this dry and apply the sample again. Make a note of which sample is placed on the spot (you can lightly write on the paper beneath the mark, using a pencil). Repeat for each sample or mixture, on a different mark and using a fresh tube or pipette each time. Let the paper dry.

Put 1cm or less of BAW into the chromatography tank. The sample spots should not dip into the solvent. Place the tank in a cool place out of direct sunlight. Stand the chromatography paper in the tank so that the bottom edge is in the solvent but the remaining paper does not touch the tank. Place the lid on the tank and leave for about 1 hour.

Wearing gloves, remove the damp paper and mark where the solvent has reached. Dry the paper in the fume cupboard. Still in the fume cupboard, spray the whole of the paper with ninhydrin in butanol. Dry the paper and transfer it to the drying oven for 1-2min.

Mark the position of each spot that develops. Note the colour and Rf (or travel distance) of each standard and hence find the amino acid composition of the unknown samples.

Hazards

See also