1.1 Mass Spectrometry steps

1 - Ionisation (Electron Impact)

(For low Mr)

— electron gun fires high energy e—s fired at sample

— ts knocks off 1 e— now everything is ion.

— X _(g) + e^- → X⁺ + 2e^-

1 - Ionisation (Electrospray)

(For high Mr)

— sample dissolved in volatile solvent

— injected through hypodermic needle as spray

— X_(g) + H⁺ → XH⁺_(g)

2. Acceleration

Ions accelerated w/ electric field so they all have same KE

3. Flight tube

— Ions enter tube (ion drift)

— lighter ions have faster time of flight. Reach detector first.

4. Detection

— Detector= negatively charged plate

— current produced when ions hit plate, e—s flow from plate to cations

— current size is proportional to number of ions