Biological/OCHEM Techniques

Thin-Layer Chromatography

stationary phase is thin layer of silica gel (polar, hydrophilic), mobile phase is usually organic solvent (weak to mid polarity), determines polarity

Column chromatography

entire column filled with silica/aluminum beads that uses gravity to move solvent up the plate to separate; size and charge determine how quickly compound moves through stationary phase

Ion exchange chromatography

beads in column coated with charged substances so that they attract or bind compounds that have an opposite charge

Size-exclusion chromatography

beads in column contain tiny pores of varying sizes that allow small compounds to enter the beads (so will move through and slower) but large compounds can’t fit (so will move around faster)

Affinity chromatography

column created with high affinity for that protein, stationary phase is often nickel…protein is first retained in column and then eluted by washing with free receptor

Gas chromatography

gas used as eluent, the injected compounds must be volatile (low melting point, sublimable solids/vaporizable liquids)

High performance liquid chromatography

sophisticated computer mediated solvent and temperature gradients used if sample size is small or if forces such as capillary action will affect results