Chromatography Flashcards
What is the basic set up of chromatography
A mobile phase= where the molecules can move, which is always a liquid or a gas.
A stationary phase= where the molecules can’t move. This must be a solid or a liquid on a solid support.
The mobile phase moves through and over the stationary phase. The distance moved depends on its solubility in the mobile phase and its retention in the stationary phase.
Thin-layer chromatography
Mobile phase= a liquid solvent like ethanol
Stationary phase=thin layer of silicon dioxide or alumina dioxide fixed to a glass or metal plate
If theres colourless chemicals such as amino acids in the mixture, you need to find a way of making them visible.
Fluorescent dye added to the silica layer that glows when UV shines.
Iodine vapour is a locating agent and shows purple spots.
Column chromatography
Purifying an organic product.
Packing a glass column with a solid, absorbent material such as aluminium oxide coated in water, called a slurry(stationary phase). A solvent is added to run through.
Retention time to identify
Gas chromatography
If you’ve got a mixture of volatile liquids, this is the best way to separate them to identify them.
The stationary phase is a solid or a solid coated in oil packed into a column The column is coiled and built into an oven.
The mobile phase is an unreacted carrier gas such as nitrogen.
The sample is vapourised and passed through the sample as a gas
Gas chromatography Mass spec
To identify and separate substances.
