TOF mass spectroscopy

Question 1

What are the stages in TOF mass spectroscopy

Answer 1

1. Ionisation
2. acceleration
3. flight tube
4. detection

Question 2

What’s involved within the first stage, ionisation

Answer 2

• Electron impact
• Electrospray
• Both produce a + ion

Question 3

What’s involved within the second stage, acceleration

Answer 3

• The + ions is accelerated/fired in between 2 negatively charged plates

Question 4

What’s involved in the third stage, flight tube

Answer 4

its mass determines how fast it travels the flight tube

Question 5

What’s involved in the fourth step, detection

Answer 5

The ion hits the negative plate at the end and therefore becomes discharged

Question 6

What are the two types of ionisation

Answer 6

Electron impact ionisation
Electrospray ionisation

Question 7

What are the steps in electron impact ionisation

Answer 7

1. Sample is vaporised
2. High energy e- fired at the sample by and electron gun —> knocks off 1 e- forming a 1+ ion

X(g) + e- —-> X^+ (g) + 2e-

Question 8

What are the steps in electrospray ionisation

Answer 8

1. Sample is dissolved in volatile solvent (water or methanol)
2. Then it is injected through a fine hypodermic needle to give a mist
3. Tip of needle is attached to a positive terminal of a high - voltage power supply
4. Particles ionised by gaining 1 H+ ion
5. Solvent evaporates

X(g) + H+ —-> XH+ (g)