Mass Spectrometry Ch1 / L4

Question 1

What is ionisation (two different methods)

Answer 1

Electron impact - Electron gun bombards sample with high energy electrons which knock off a valence electron - X(g) -> X+(g) + e-
Electrosplay ionisation - Gains a proton from a solvent as the solvent is injected through a high volate hypodermic needle - X(g) + H+ -> XH+ (g)

Question 2

How does acceleration occur

Answer 2

Cations are attracted through a magnetic field, created by a seried of plates, accelerating the cations to the same kinetic energy. Since the cations have the same kinetic energy their velocity will depend on their charge and mass

Question 3

What is ion drift - What factors affect the velocity of the ions during ion drift

Answer 3

The ions will pass through a hole in the negatively charged plate and move into a flight tube.
Charge and mass

Question 4

How are the ions detected

Answer 4

Once the ions have passed through the plate the 1+ ions will hit a negatively charged detector plate causinf them to gain an electron and creating a current.

Question 5

What quantitied are measured by the detector

Answer 5

M/Z ratio
Abundance

Question 6

What are some applications

Answer 6

• Calculation of Ar and Mr
• Quality assurance testing in pharamceuticals, agriculture and food industries
• Detecting illict substances in urine/ blood / breath tests
• Detecting compounds on space missions