Mass Spectrometry

Question 1

What is mass spectrometry?

Answer 1

• technique used to measure the mass of atoms or molecules and the presence and relative abundance of isotopes

Question 2

Stage 1

Answer 2

Vaporisation:
- a sample of the element is vaporised in a vacuum then passed into the mass spec

Question 3

Stage 2:

Answer 3

Ionisation:
- the sample passes through a high energy electron beam
this causes the atom to lose 1 electron (makes + ion), it can sometimes lose 2 (makes 2+ ion)

Question 4

Stage 3:

Answer 4

Acceleration:
- the sample is accelerated by an electric field
- forms a high speed beam of positive ions through a strong magnetic field
- ions are deflected by the field and move in circular paths with a different radius
- ions with low mass and high charge experience more deflection

Question 5

Stage 4:

Answer 5

Detection:
- the detector measures the intensity and radius of ion deflection
- detector count: measure of isotopic abundance
- degree of beam deflection: related to isotopic mass
- results can be tabulated as a mass spectrum