Extractive electrospray ionization (EESI) is a spray-type, ambient ionization source in mass spectrometry.

Many ambient ionization sources like EESI were developed for biological samples.

CI is a soft ionization source, so it is better than EI.

Like CI, MALDI is a soft ionization source and analyzes both semi-volatile organic compound and biological compounds.

HPLC of lipids may either be performed offline or online where the eluate is integrated with the ionization source of a mass spectrometer.

Arthur J. Dempster develops the spark ionization source.

Most commonly, an electrospray ionization source is used in LC/MS.

All these are even-electron ion species: electrons (alone) are not added or removed, unlike in some other ionization sources.

Ions can be either generated inside the cell or can be injected to the cell from an external ionization source.

His research into ionization sources also enabled many other discoveries in biomedical sciences.