Chemistry - Mass Spectrometer

MASS SPECTROMETER

1.) Vaporisation and ionisation - ELECTROSPRAY -a sample is dissolved and pushed through a small nozzle at high pressure. A high voltage is applied causing the particle to lose an electron and turning the sample into a gas of positive ions.

ELECTRON GUN - a sample is vapourised, high energy electrons are fired from a hot filament wire, knocking out othe elctrons, often leaving molecules in fragments.

Acceleration - the positive ions are accelerated by an electrical field of negative charge. Ions with a low mass/charge ratio experience greater acceleration.

Ion drift/time of flight - when the ions leave the electrical field they have a constant speed with their kinetic energy. They enter a region of no electrical field so they drift, ions with a lower mass/charge ratio drift at higher speeds.

Detection - because ions that have a lower mass/charge ratio travel at higher speeds, they reach the drift region faster than those with a higher mass/charge ratio. When the ions hit the detector a current is produced.