| Chromatography is a term which may refer to any | | | | used to provide a measurement of the concentration |
| number of different methods of separating the | | | | of components of the sample being tested. This |
| different components of analytes for preparative or | | | | method may also be used to find out if a given |
| analytical applications. While the particulars of each of | | | | analyte is in fact present in a sample at all. While their |
| type of chromatographic process vary, essentially | | | | aims may differ, preparative and analytical |
| what happens is this: an analyte or mixture containing | | | | chromatography may in fact be performed in a single |
| an analyte is combined with a solvent to form a liquid | | | | operation. |
| or gas (or supercritical fluid in some cases) known as | | | | The most familiar chromatographic testing to most |
| the mobile phase. The mobile phase is then passed | | | | people is the columnar method, though paper (which |
| through a medium fixed in place called, | | | | relies on the different rates at which materials bond |
| understandably enough, the stationary phase; this | | | | with a sheet of cellulose), planar and thin layer (which |
| material is often silica, but varies depending on the | | | | both often use a sheet of glass as a substrate |
| type of chromatography being performed. | | | | underneath a layer of silica or cellulose) |
| The differing physical or chemical properties of the | | | | chromatographic methods are also common. There |
| constituent components of the mobile phase cause | | | | are in fact many different methods available, with |
| them to pass through the stationary phase at | | | | some being better suited to specific applications or |
| different rates; a process which separates the | | | | different analytes. The state and type of analyte to |
| analyte from the other components of the mobile | | | | be tested for and the purpose of the separation |
| phase. These different partition coefficients, as they | | | | largely determine whether liquid or gas |
| are known, are the basis for chromatographic | | | | chromatography and which particular type is |
| preparation and analysis in the laboratory. Essentially, | | | | appropriate. |
| the less affinity which a given component in the | | | | These technologies are useful not only in research |
| mobile phase has for the material of the stationary | | | | laboratories but are also extensively used in the |
| phase, the more quickly it will pass through the | | | | production of chemicals and biotechnology products, |
| column. It's a bit more complicated than all that, of | | | | where it is most commonly used as a separation and |
| course, but this is the general principle behind | | | | purification method. The precision which the |
| chromatography. | | | | chromatographic process allows for the separation of |
| In preparative chromatographic applications, the idea | | | | even the most complex of mixtures where the |
| is to separate the constituents of the mobile phase, | | | | constituents have only the minutest variation. |
| which are then often put to use elsewhere in the | | | | Provided the proper solvent and the proper medium |
| laboratory. It can be an efficient purification process | | | | as the stationary phase, virtually any mixture which is |
| with certain materials and may be done in nearly any | | | | soluble can be separated this way, making |
| quantity as needed. Analytical applications, on the | | | | chromatography one of the most common |
| other hand, are usually performed using much smaller | | | | procedures in laboratories. |
| volumes of material, with the chromatograph being | | | | |