Gentle ionisation methods MALDI and ESI

In MALDI the ionisation energy is provided by a pulsed laser beam. The substance to be analysed is dissolved in a matrix (e.g. 2,5-dihydroxybenzoic acid 2,4,6-trihydroxyacetophenone) which absorbs in the wavelength range of the 

In contrast to MALDI the principle of ESI is based on fine spraying of sample solution. The initially formed electrically charged droplets are rapidly desolvated, permitting the individual dendrimer species to be observed as isolated ions in the mass spectrum. 

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