Chromatography Flashcards
What state is the mobile phase?
It may be a liquid or a gas
What is chromatography?
An analytical technique that separates components in a mixture between a mobile phase and a stationary phase
What state is the stationary phase?
May be solid (in TLC) or either a liquor or solid on a solid support (in gas chromatography)
How does a solid stationary phase separate?
Adsorption
How does a liquid phase separate?
Relative solubility
What is the Rf value?
Distance moved by component/distance moved by solvent front
What is a phase?
A physically distinctive form of a substance, such as the solid, liquid and gaseous states of ordinary matter.
What is the mobile phase?
The phase that moves in chromatography
What is the stationary phase?
The phase that does not move in chromatography
What is adsorption?
The process by which a solid holds molecules of a gas or liquid or solute as a thin film on the surface of a solid or, more rarely, a liquid.
What is retention time?
The time for a component to pass from the column inlet to the detector in gas chromatography
What are the limitations of analysis by gas chromatography?
- similar compounds have similar retention times
- unknown compounds have no reference retention times for comparison
Why do we combine mass spectrometry with chromatography?
- to provide a far more powerful analytical tool than from just chromatography
- to generate mass spectra which can be analysed or compared with a spectral database for positive identification of a component.
What are some uses of GC-MS in analysis?
- forensics
- environmental analysis
- airport security
- space probes
