Year 12 - The Mass Spectrometer

Question 1

Name the 4 things which happen when a sample is ‘squirted’ into a time of flight (TOF) mass spectrometer. Hint: IAID

Answer 1

1 - Ionisation: The sample needs to be ionised either via electrospray (sample is dissolved in solvent and pushed through a small nozzle at high pressure, high voltage applied so each particle gains a H+, solvent removed leaving gas made up of H+ ions) or electron impact (sample is vaporised, electron gun fires high energy electrons at it, knocking an electron off leaving each particle as a +1 ion).
2 - Acceleration: Positive ions accelerated by an electric field, all ions given same amount of kinetic energy however lighter ions are able to travel at a faster speed.
3 - Ion drift: Ions drift through an area where there is no electric field, travel at same speed as before so lighter ions travel faster still.
4 - Detection: Lighter ions reach detector first , detector detects current created when the ions hit it and records how long it took to pass through spectrometer. This data is then used to calculate the mass/charge values needed to produce a mass spec.