A form of non linear chromatography where the migration of the solutes is
due to a displacement by an additive that strongly adsorbs to the stationary
Modification of the properties of the stationary phase surface by using an
additive in the mobile phase that adsorbs to the surface.
It would be tempting to try to explain paper chromatography in terms of the way that different compounds are adsorbed to different extents on to the paper surface. In other words, it would be nice to be able to use the same explanation for both thin layer and paper chromatography. Unfortunately, it is more complicated than that!
Column back pressure:
The difference in pressure between the column inlet and outlet.
The form of chromatography which uses a column or tube to fix the stationary
Column plate number:
See Plate number.
Pour a reasonable amount of your solvent into a container and place the bottom edge of the Chromatography paper in the solvent.
Wait for the solvent to stop "creeping" up the paper and remove the paper from the solvent.
Although paper chromatography is simple to do, it is quite difficult to explain compared with thin layer chromatography. The explanation depends to some extent on what sort of solvent you are using, and many sources gloss over the problem completely. If you haven't already done so, it would be helpful if you could read the explanation for how thin layer chromatography works (link below). That will save me a lot of repetition, and I can concentrate on the problems.
Ion chromatography (IC):
A technique in which low concentrations of ionic solutes are determined by
using ion exchangers of low exchange capacity and mobile phase with low
The exclusion of co-ions from the surface layer. In chromatography the ion
exclusion effect implicates that co-ions migrates faster through the column
than a neutral molecule.
Ion moderated partitioning chromatography:
A technique used for separating carbohydrates by using a strong cation
Ion pair chromatography:
A form of reversed phase chromatography in which a charged organic molecule,
the ion pair reagent, is added to the mobile phase. The ion pair reagent
adsorbs to the stationary phase surface and creates a charged surface layer.
Ions of opposite charge are attracted to the charged surface layer and ions
of the same charge are repelled . The retention of ions is modulated by
changing the concentration of ion pair reagent in the mobile phase.
Gel filtration chromatography (GFC):
Chromatographic separation according to molecular size usually performed in
an aqueous mobile phase on soft gels such as polydextrans.
The chromatographic technique by which a mobil phase gradient is used to
modulate the retention times. Usually the mobile phase composition changes
so that its strength increases with time.
Graphitized carbon packing:
A stationary phase consisting of pure graphitic carbon.
A small column that protects the analytical column from contamination, it is
placed between the injector and the analytical column.
A term used in preparative chromatography and column switching for the
collection of the center of a peak.
High performance liquid chromatography (HPLC):
A term coined for the modern and instrumentally developed form of column
liquid chromatography. It is characterised by high flow rates and high back
Hydrophobic Interaction Chromatography (HIC):
A chromatographic technique which is primarly used to separate proteins. The
technique is characterised by a hydrophilic solid support with a low
coverage of short carbon chains. The mobile phase is a buffered water
solution with a steep gradient of decreasing salt concentration.
Abbreviation for ion chromatography
Stationary phases which are generated in the presence of a template molecule
so that a "footprint" of the molecule is created on the stationary phase.
The imprinted phase has a strong selectivity for the template molecule.
A detection technique where the solute is indirectly detected by measuring
the change in mobile phase composition at column outlet. A prerequisite for
this technique is that the adsorption isotherm of a component in the mobile
phase depends on the concentration of the solute. E.g. a non-UV absorbing
solute is indirectly detected with an UV-detector by adding an UV absorbing
component to the mobile phase. If the adsorption isotherm of this component
depends on the concentration of the solute, its variation in concentration
at the column outlet, caused by the elution of the solute, can be detected
with an UV-detector.
The tendency for a compound to divide its time between two immiscible solvents (solvents such as hexane and water which won't mix) is known as . Paper chromatography using a non-polar solvent is therefore a type of .
Because they spend more time dissolved in the stationary phase and less time in the mobile phase, they aren't going to travel very fast up the paper.
It is a very long and arduous process that may not yield any definitive results.
A student separated out the pigments found in plant leaf.
A diagram of the inside of a gas chromatograph.
So, Why These Solvents?
We chose acetone and distilled water because they are polar opposites.