Chromatography Flashcards
In chromatography, the mobile phase 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
In chromatography, the stationary phase may be…
A solid (as in thin layer chromatography) or either a liquid or sold on solid support (as in gas chromatography)
In chromatography, a solid stationary phase separates by…
Adsorption
In chromatography, a liquid stationary phase separates by…
Relative solubility
Rf value =
Distance moved by component / distance moved by solvent
What is retention time?
The time taken for a component to pass from the column to the detector
In a gas chromatogram, the area under each peak is proportional to…
The amount of a compound in the sample
What are the limitations of gas chromatography?
Similar compounds often have similar retention times, making it hard to positively identify compounds
Unknown compounds have no reference retention times for comparison
Why is gas chromatography often combined with mass spectrometry?
To provide a far more powerful analytic took than from chromatography alone
To generate mass spectra which can be analysed or compared with a special database by a computer for positive identification of a component
What are the uses of gas chromatography - mass spectrometry?
Forensics, environmental analysis, airport security, and space probes
