HMDB (Human Metabolome Database), METLIN, MassBank, and lipid-specific libraries (LIPID MAPS, SwissLipids) provide accurate mass, adduct ions and fragment information for compounds, forming the underlying basis for MSI peak annotation.
These libraries are broad and actively updated; combined with high-resolution accurate mass and tandem-MS fragments, they can narrow an unknown m/z to a few candidate compounds, the first step of annotation work.
METASPACE is currently the most representative MSI annotation cloud platform: it maps the acquired data onto public metabolite databases and automatically produces spatial annotation results, greatly lowering the barrier to small-molecule annotation.
The advantage of such platforms is bundling 'database + statistics + visualization,' letting researchers without a mass-spectrometry background also obtain interpretable annotation maps, though candidate and histological plausibility still need manual verification.
With the rise of spatial transcriptomics and spatial proteomics, demand has emerged to register MSI with these modalities. Relevant resources include analysis pipelines and reference datasets that overlay metabolic, transcriptional and protein information on tissue coordinates.
Such resources help answer 'does a metabolite-enriched region correspond to a high-expression region of a certain gene/protein,' moving MSI from single-modality to multi-omics integration, a frontier direction in spatial biology.
Database annotation is a 'candidate' rather than a 'confirmation': isomers, adduct-ion ambiguity and tissue matrix effects can all cause misannotation, so key conclusions require validation by standards or MS/MS.
Practical advice: first use HMDB/METLIN/LIPID MAPS for candidates, then use METASPACE-like platforms for batch annotation, and finally confirm key molecules by tandem mass spectrometry or standards, and register the images with H&E to confirm their histological location.
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).