Separating organic compounds is a common and important tool for learning about what chemicals can be found in various cells.
Column chromatography is an effective method for sorting large molecules from smaller molecules. Using this technique, scientists could quickly separate out a particular molecule from all the others if they know the molecule’s size. Typically, heavier molecules are larger.
Paper chromatography separates molecules according to their solubility in a particular solvent. This technique, like column chromatography, allows scientists to quickly separate a particular molecule from others, as long as the solubility of the molecule is known.
Gel electrophoresis separates molecules according to their charge, shape, and size. This method of separating molecules is quickly becoming the most common and important technique in science because it is most often used in genetics research. Gel electrophoresis allows one to ‘fingerprint’ DNA which can be used in forensic investigations, determining the relatedness of individuals or even species, and discovering new mutations. | 
2002 McGraw-Hill Higher Education