WM 4- Mass Spectrometry

Question 1

Give some uses of mass spectrometry

Answer 1

• identify unknown compounds

- determine isotopic abundance of element

Question 2

Give the 4 steps involved in mass spectrometry

Answer 2

1. Sample is converted to gaseous ions (by being bombarded with electrons)
2. Ions are propelled by electric field into analyser
3. Ions are deflected by magnetic/electric field, separated by mass-charge ratio
4. Ions are detected

Question 3

If you have a graph showing the relative abundance of isotopes of an element, how do you calculate the relative atomic mass?

Answer 3

Sum of relative abundance times atomic mass, over 100

Question 4

What is ‘M+’?

Answer 4

Molecular ion- positive ion when molecule loses an electron

Question 5

What is ‘fragmentation’ in mass spectrometry?

Answer 5

When a molecular ion, M+, splits into pieces, one of which Isis positive fragment ion