Mass Spectrometer

Question 1

Step 1 - Vaccum

Answer 1

Kept in a high vacuum to prevent ions produced from colliding with the air

Question 2

Step 2 - Ionisation (Option 1)

Answer 2

Electrospray Ionisation:
- Sample dissolved in a volatile solvent
- Forced through a fine hollow needle
which is connected to a high voltage
supply
- Produces tiny positively charged
droplets that has gained a proton
from the solvent
- Solvent evaporates from the droplets
until a single positively charged ion

Question 3

Step 2 - Ionisation (Option 2)

Answer 3

Electron Impact:
- Sample is vapourised
- High energy electrons are fired from
an electron gun
- Knocks off 1 electron. Forming a 1+
ion

Question 4

Step 3 - Acceleration

Answer 4

Positively charged ions attracted to negatively charged plates. Causes ion to accelerate.
Lighter and highly charged ions move at higher speed

Question 5

Step 4 - Ion drift

Answer 5

ions pass through a hole in the negative plate, forming a beam from flight tube to detector

Question 6

Step 5 - Detection

Answer 6

ions with the same charge arrive, and the lighter ones are the first to arrive as they have higher velocities. TOF recorded. Positive ions pick up an electron causing a current to be formed

Question 7

Step 6 - Data analysis

Answer 7

signal from detector is passed to a computer which generates a mass spectrum

Question 8

low resaloution
high resaloution

Answer 8

1 d.p
5 d.p

Question 9

Average relative atomic mass

Answer 9

                   100