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6 Cards in this Set

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Stage 1: Ionisation - Electrospray Ionisation

-Sample is dissolved in a solvent


-Injected through a needle at high voltage


-Gains a proton

Solvent, Needle & Proton

Stage 1: Ionisation - Electron Impact (Electron Gun)

-High energy electrons from an electron gun


-Fired at the sample and knock off an electron

The Lion King

Stage 2: Acceleration

-The positive ions are accelerated by an electric field to a constant kinetic energy


-The rate at which they are accelerated is dependent on their masses


-Ions with a lower mass will travel faster and will have a higher velocity


-Ions with a higher mass will travel slower and will have a lower velocity

Electric Field, Kinetic Energy, Mass & Velocity

Stage 3: Ion Drift

-Ions will separate (All Ions have a constant kinetic energy)


-Ions are allowed to drift in a flight tube and the time it takes for the Ions to reach a detector at a known distance in measured


-This time will depend on the mass of the ion


-Lighter Ions reach higher velocities, therefore Ions with a low mass will reach the detector first and those with a high mass will arrive last


-The mass of the Ion can be determined from the time taken for the Ion to reach the detector

Separate, Time, Distance, Mass & Velocity

Stage 4: Ion Detection

-Positive Ions hoy the detector (a negatively charged plate) and pick up electrons


-A current is generated when the Ions gain an electron


-The greater the abundance of the Ions hitting the detector, the bigger the current produced

Detector, Current & Abundance

Stage 5: Data Analysis

-The detector is linked to an amplifier and recorder, which converts the current into a peak and that is shown in a mass spectrum


-The height of the peak is proportional to the size of the current generated and therefore proportional to the abundance of the Ion


-Flight times are analysed and recorded as a plot of abundance v mass/charge ratio or m/z

Peak, Height, Current and Ratio