Chromatography Flashcards
What does chromatography involve that separates components?
A mobile phase and a stationary phase.
What is chromatography?
Separation technique in which a mobile phase carrying a mixture moves in contact with a selectively absorbent stationary phase.
What is ultraviolet absorption spectrometry?
Technique involving the absorption of UV radiation. It is a quantitive technique and is used to measure the amount of a substance in a sample.
What is the principle behind UV absorption spectrometry?
Absorption of UV radiation by molecules results in the promotion of electrons from their ground state to higher energy levels. Absorbance is directly proportional to conc.
List the processes involved in UV absorption spectrometry.
- UV light is passed through the sample and a blank.
2. An absorption spectrum is obtained.
What is infrared absorption spectrometry?
Quantitative technique involving the absorption of IR. Useful for identifying organic compounds.
What are the principles of IR absorption spectrometry?
Molecules of a substance absorb IR light of different frequencies. The combination of frequencies absorbed is peculiar to the molecules of that substance.
What processes are involved in IR absorption spectrometry?
- IR radiation passes through the sample.
- Sample absorbs IR radiation at specific frequencies which are detected
- An absorption spectrum is obtained.
What kind of organic compounds can IR absorption spectrometry identify?
Plastics and drugs.
What is the principle behind HPLC?
Different components of a mixture have different tendencies to adsorb onto very fine particles of a solid in the HPLC column.
What processes are involved in HPLC?
- Injection
- Transport sample along column
- Separation in the column
- Detection.
What is the principle of GC?
Different components of a mixture have different interactions with the stationary and mobile phases.
What processes are involved in GC?
- Injection
- Transport sample along column
- Separation in column
- Detection.
How do you calculate Rf values?
Divide distance travelled by component by distance travelled by the solvent front.
What are the 3 simple chromatography methods?
Paper, thin layer and column.
