Two phases in contact, one moving and one stationary, dissolve solute with different solubilities or adsorb solute at different rates {chromatography}|.
purposes
Chromatography is non-destructive, separates mixtures into groups, and can be quantitative.
phases
Stationary phase is starch or diatomaceous earth on columns or plates {chromatograph}. Solid substrate saturates with solvent. Moving phase is solvent at constant pH and salt concentration.
process
Solute in solution starts at saturated-substrate edge. Solvent flows through saturated substrate. Molecules transfer back and forth between mobile and stationary phases.
Depending on relative solubility, molecules spend different times in phases. Molecules that are more soluble in moving phase than in stationary phase move faster. Molecule polarity, size, shape, and charge in solution affect movement rate. Smaller compounds elute faster.
diffusion
Molecules diffuse, so peaks can be wide if flow rate is slow and time is long.
types
Gas or liquid mixtures can separate using gas chromatography, liquid chromatography, supercritical fluid chromatography, or capillary electrophoresis.
Physical Sciences>Chemistry>Analytical Chemistry>Chromatography
5-Chemistry-Analytical Chemistry-Chromatography
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Date Modified: 2022.0224