Fresh or perfused tissue is first fixed by liquid nitrogen or dry freezing, embedded in OCT, then cut into 10–20 μm thin sections attached to glass slides; the MALDI route then uniformly sprays matrix, while DESI and LDPI and other ambient matrix-free sources go directly on the instrument.
The key is timely fixation to prevent metabolites from diffusing after death and destroying spatial authenticity; section thickness must match the scan step size (see section thickness).
Blood can be smeared, made into dried blood spots, or separated into blood cells or plasma and then spotted into a film; urine is mostly analyzed after evaporation, freeze-drying or substrate enrichment. The goal is to convert the liquid into a spatially resolvable thin layer while retaining metabolite or drug distribution information.
Body-fluid samples have weak spatial information (mostly homogeneous); the value of imaging often lies in fingerprint-style distribution or deposition localization; if organ distribution is of interest, tissue sections remain the primary choice.
Leaves can be analyzed whole or after transverse or longitudinal sectioning, focusing on the accumulation gradient of secondary metabolites (such as phenolics, alkaloids) in space. Plant cell walls are thick and the matrix is complex, so the MALDI matrix penetration and DESI desorption parameters need optimization for the tissue.
Plant research is often linked with the plant mass spectrometry imaging topic, where pretreatment can be designed across species, tissue site and developmental-stage dimensions.
Unify the fixation method, section thickness, storage temperature and (if applicable) matrix process; set solvent or blank controls per batch and record freeze-thaw cycles.
Pretreatment is the first step that determines the credibility of imaging data; fixing the methodology and inter-batch consistency matter more than a single pretty image.
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).