The two practical applications for chromatography paper are in the analysis of colored substances and tiny amounts of mixtures. Forensic investigators use it for identifying the components in paint mixtures and drug mixtures.
Colored plant pigments and artificial food colors are analyzed using paper chromatography by chemists. In forensics, components of drugs that can range from aspirin to narcotics in blood and urine samples are determined by using it. A car paint sample can be analyzed to determine which vehicle it came from, the vehicle's model and manufacture year. In counterfeiting or forgery, the sample of ink can be analyzed to determine which pen it came from and the kind of ink that was used.
Chromatography means writing in color. It is a common technique used for segregating ions or molecules depending on their composition and interactions during stationery and mobile phases. A test preparation, which contains the sample to be segregated, is applied on the chromatography paper. The paper is then put into a container with its edge touching a specific solution in the container. This is called the "stationery phase." Due to capillary action, the solution moves up the paper, which is known as the "mobile phase." When the solution reaches the sample spot or line on the paper, the molecules or ions in the sample move up the paper together with the solution. The speed of the ions or molecules depend on their solubility in the solution. The more soluble they are, the faster they move. This leads to the formation of a chromatogram or paper with various segregated ion or molecule spots.