After the tissue is quickly frozen by liquid nitrogen or cryogen, it is cut into thin layers of a few to a dozen-plus micrometers with a blade in a cryostat at constant low temperature. The low temperature inhibits enzyme activity and diffusion, freezing molecules in situ, thereby reducing spatial distortion caused by sample preparation.
Compared with the paraffin process requiring dehydration, embedding, and dewaxing, frozen sectioning bypasses organic-solvent exposure and is more friendly to heat-sensitive and easily eluted metabolites.
Frozen sectioning has high fidelity and is a common sample preparation for spatial metabolomics, drug distribution, and lipid imaging; when paired with matrix-free ambient sources (LDPI, DPI, DESI), it can be sampled directly after sectioning, with a short chain and little disturbance.
For imaging requiring subcellular resolution, the frozen process can also coordinate with a cryo-mass-spectrometry imaging source to lock in-situ distribution on the low-temperature chain, avoiding molecular migration caused by thawing.
Key parameters include freezing rate (affecting ice-crystal size), sectioning temperature, thickness, and blade condition. Too-large ice crystals destroy microstructure, and unstable temperature introduces knife marks or wrinkles. After sectioning, image as soon as possible or store at low temperature to prevent sublimation and degradation.
If subsequent H&E or IHC annotation is needed, frozen sections are also compatible, but attention must be paid to the effect of the staining process on the mass spectrometry target surface; conductive slides are used for vacuum sources requiring conductivity (such as TOF-SIMS).
Frozen sectioning should be included in the standard imaging SOP: unified freezing storage, section thickness, and transfer conditions to ensure multi-sample comparability. Section quality together with subsequent matrix spraying (if MALDI is used) or matrix-free sampling (LDPI/DPI) determines the final image quality.
For matrix-free ambient imaging lines, a short chain of frozen sectioning to direct sampling is recommended to maximize retention of small-molecule spatial information.
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).