Ambient ionization techniques take many forms: DESI uses electrospray impact for surface desorption; DART uses inert gas through dielectric barrier discharge to generate excited species that ionize surface molecules; APCI/APPI are mostly used for liquid effluent mass spectrometry (non-imaging); LDPI achieves matrix-free imaging via laser desorption plus photoionization.
These techniques share the idea that the sample need not enter vacuum, but only those with point-by-point scanning capability (such as DESI, LDPI, and DART with a moving platform) are used for imaging; the rest mostly serve direct-injection rapid analysis.
In the MSI context, the value of ambient ionization is upgrading direct ionization into spatially resolved direct ionization. DESI and LDPI are typical imaging-type ambient sources; DART can also perform 2D scanning with a moving platform, but its resolution and applicability are weaker than dedicated imaging sources.
Understanding this distinction helps avoid conceptual mixing: ambient ionization is the broader family, and ambient imaging ion source is its spatially resolved subset.
DESI/AFADESI suit tissue-scale metabolism/lipids; LDPI suits single-cell/subcellular small-molecule low background with matrix-free, 2-3 um; DART suits rapid surface screening; APCI/APPI suit LC effluent ionization.
Selection depends on whether spatial resolution is needed, whether matrix-free is required, the target molecule, and the host form. Neo-Source LDPI/DPI bring ambient ionization into mainstream mass spectrometry imaging via external add-ons.
To obtain detailed specifications, compatible models, or a quotation for the MSI LDPI / DPI full series imaging ion sources, visit the Neo-Source official website, or contact the official team for compatibility advice tailored to your mass spectrometer (Agilent / SCIEX / Thermo and other mainstream MS).