Paper chromatography is the separation of colored substances and chemicals which happen to possess a
similarity in polarity. The mobile phase of this method is a solvent mixture, while the stationary phase is a
thin piece of absorbent paper. It is a fast separation method that needs small material samples.
How it works
Any person who has been to school has at one point carried out this easy demonstration of paper
chromatography. Pick an ink pen and put a spot on the paper towel. Dip this paper in a solvent such as
water or even alcohol. You will see action as certain substances move upwards on the paper. These
substances are called molecules. Each molecule is made up of unique characteristics which determine the
speed at which they separate. As separation takes place, you are bound to see colored or colorless
components. Using developing fluids helps you identify these components.
Even though the evolvement of more complex methods of separating substances has reduced it into a
training tool, there still remains many ways and incidences where this method has come in handy. Eg,
when unidentifiable substances are left at scenes of crime, this type of chromatography can be used to
separate the molecules. After separation, the mysterious chromatograms are matched with recognizable
chromatograms which help in identifying the substance.
In analytical chemistry, this method is used to separate and determine colored mixtures. Scientists have
found this method to be particularly helpful in the separating organic and inorganic matter in mixtures.
Classification of Deoxyribonucleic and Ribonucleic acids too is dependent on this procedure.
Separation and identification of intricate mixtures of amino acids, steroids, carbohydrates, peptides, and
purines among others are done through this method.
Paper chromatography techniques include;
Ascending-descending paper technique
Radial paper technique
Two dimensional paper techniques