MS - Spectrometers

Question 1

Quadrupole

Answer 1

Cheapest
4 metal rods
RF voltage applied to pairs of rods (2 x 2)
Only ions with right m/z will reach detector, other ions collide with rods

Question 2

Triple quad

Answer 2

3 quadrupoles in linear series
Q1 + Q3 = mass filters
Q2 = collision cell (fragmentation)
Increased sensitivity + specificty

Question 3

Time-of-Flight

Answer 3

1. Ions are given same amount of E with pulse
2. Ions move at speed determined by mass
3. Distance is known, time is recorded

Speed is the advantage

Improving resolution:

• Delayed extraction
• Reflectron

Question 4

Ion cycltron (ICR)

Answer 4

1. Ions in magnetic field
2. Ions rotate –> induce current when close to plate (= sine wave)
3. f sine wave used to deduct m/z (B is known)

Fourier transform

Question 5

Orbitrap

Answer 5

Like ICR but with electric field

Cheaper