Chromatography Flashcards
GC - liquid stationary phase
Liquid stationary phase separates by relative solubility. Components dissolve in stationary phase. The greater the solubility e.g alcohols and carboxylic acids, the more the component molecules slowed down so the lower the Rf value.
Limitations of TLV
Similar compounds have similar Rf values. Unknown compounds have no reference Rf for comparison. Difficult to find solvent that separates all components in a mixture - of components very soluble they will be washed up plate with solvent front, if little solubility they will hardly move.
Limitations of GC
Similar compounds have similar retention times. Not all substances can be separated and detected. Unknown compounds have no reference retention times for comparison.
TLC - solid stationary phase
Stationary phase is solid/on solid support and separates by adsorption. In adsorption the component molecules bind to the solid stationary phase. The stronger the adsorption to stationary phase the more the component molecules are slowed down so the lower the Rf value.
