Paper chromatography is a type of chromatography in which
absorbent paper is used. The mixture to be analyzed is dissolved and a drop
of the solution placed near one edge of the sheet of paper. The sheet is
suspended vertically with that edge dipping into a trough of solvent.
As the solvent rises up the paper by capillary
action, the components in the spot move with the solvent front at different
rates, depending on their composition. When the paper is dried, the components
appear as a line of spots, which may need spraying with a reacting substance
to color them and reveal their presence. The distance of a substance moves
in a given time is characteristic of its identity.
|A scientist studying a selection of paper chromatograms
of industrial dyes. Paper chromatography involves placing a small
amount of the substance under investigation on a piece of filter paper,
then slowly dripping a solvent into the center of the paper. The solvent
then spreads out over the paper by capillary action, carrying with
it the components of the substance at differing rates. The distance
traveled along the paper by each component during the time of the
experiment is a measure of the characteristic transport rate and may
be used to identify each component.