Principle
The basic principle of displacement chromatography is: there are only a finite number of binding sites for solutes on the matrix (the stationary phase), and if a site is occupied by one molecule, it is unavailable to others. As in any chromatography, equilibrium is established between molecules of a given kind bound to the matrix and those of the same kind free in solution. Because the number of binding sites is finite, when the concentration of molecules free in solution is large relative to the dissociation constant for the sites, those sites will mostly be filled. This results in a downward-curvature in the plot of bound vs free solute, in the simplest case giving a Langmuir isotherm. A molecule with a high affinity for the matrix (the displacer) will compete more effectively for binding sites, leaving the mobile phase enriched in the lower-affinity solute. Flow of mobile phase through the column preferentially carries off the lower-affinity solute and thus at high concentration the higher-affinity solute will eventually displace all molecules with lesser affinities.
Read more about this topic: Displacement Chromatography
Famous quotes containing the word principle:
“Country people do not behave as if they think life is short; they live on the principle that it is long, and savor variations of the kind best appreciated if most days are the same.”
—Edward Hoagland (b. 1932)
“It were as wise to cast a violet into a crucible that you might discover the formal principle of its colour and odour, as seek to transfuse from one language into another the creations of a poet. The plant must spring again from its seed, or it will bear no flower—and this is the burthen of the curse of Babel.”
—Percy Bysshe Shelley (1792–1822)
“Antagonistic cooperation is the principle of all markets and many marriages.”
—Mason Cooley (b. 1927)