is a process in which a chemical mixture carried by a liquid or gas is separated into components as a result of differential distribution of the solutes as they flow around or over a stationary liquid or solid phase. There are two main categories of chromatography: preparative and analytical. A sample to be separated, when placed on the stationary section, will gradually move along in the same direction as the mobile phase. If a sample compound (or analyte) has no interaction with the stationary phase, it will run right through and come out of the system (elute) at the same rate as the mobile section. On the opposite hand, if an analyte has no interaction with the mobile phase, it will stick on to the stationary phase and never elute. Neither of these are good outcomes.