CD 6 - Modern Analytical Techiques

Question 1

What is gas-liquid chromatography?

Answer 1

A type of chromatography used to separate and analyse compounds that are in the liquid or gaseous phase

Question 2

What are some uses of gas chromatography?

Answer 2

Uses include:
- Testing how pure a substance is
- Separating all the different components in a mixture

Question 3

How is gas-liquid chromatography carried out?

Answer 3

• The mixture is injected into the column (lined with a high boiling point liquid on a porous support) where it vaporises and is carried through the column by an inert carrier gas
• Compound move through the column at different rates due to solubility and volatility
• Compounds pass through a detector at the end of the column. This produces a gas chromatogram
• Each peak = different compound

Question 4

What is retention time?

Answer 4

The time taken from the injection of the mixture to the detection of the compound

Question 5

What does the retention time of a compound allow you to do?

Answer 5

Compare the time to known values to help identify the compound

Question 6

What technique is usually used for further analysis?

Answer 6

• Mass spectrometry
• This will allow you to calculate the molecular mass of the separated products