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Soft ionisation methods

Electrospray ionisation (ESI)

Electrospray ionisation is the most commonly used method for mass spectrometry analysis in the department. It is quick and easy to run, and usually results in the molecule of interest being ionised as a protonated (M+H⁺), sodiated (M+Na⁺) or potassiated (M+K⁺) species. Peaks in the resulting spectrum therefore correspond to the molecular mass plus 1 for H, 23 for Na or 39 for K.

Atmospheric Pressure Chemical Ionisation (APCI)

APCI is an alternative ionisation technique which is routinely available and may be more suitable for some samples.

Hard ionisation methods

Electron ionisation (EI)

Electron ionisation involves the sample being ionised into the gas phase and the molecules colliding with electrons which results in the formation of positive ions through the fragmentation of the molecule, with these fragments being detected.