DESI forms a Taylor-cone spray at the capillary tip under high voltage; charged droplets guided by inert gas strike the sample surface, dissolve and carry surface molecules, then desolvate and ionize in the gas phase, and ions enter the mass analyzer via an interface.
Since both desorption and ionization occur at ambient pressure, the sample need not be placed in vacuum and no matrix is needed; sample prep is only sectioning and positioning, greatly simplifying the workflow and supporting near in-situ analysis.
The core advantages of DESI are ambient operation, matrix-free, simple sample prep, and fast sample turnover, excelling at the tissue distribution of metabolites, lipids, drugs and their metabolites. It is especially suitable for clinical/pharmacological high-throughput sections.
It can also analyze hydrated or fresh samples to some extent, extending in-vivo and in-situ scenarios. These features make it a common ambient source for spatial metabolomics and pharmacological imaging.
The main limits of DESI include polarity bias (low response for some molecules), ion suppression (competition from co-eluting surface species), and resolution mostly at tens to hundreds of microns, at the tissue scale. Solvent formulation and scan parameters need systematic optimization.
Improvement directions include AFADESI (air-flow-assisted, improving sensitivity and uniformity), and supplementing single-cell scale and small-molecule low-background needs with matrix-free high-resolution sources such as LDPI, forming a multi-source complementarity.
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).