LDPI consists of two stages: laser desorption and photoionization. A pulsed laser irradiates the sample surface to desorb molecules, while neutral molecules in the desorption plume are converted into ions by photoionization, and then collected by the mass analyzer. This path does not rely on organic matrix co-crystallization, eliminating matrix peaks from the low-mass region at the source.
Photoionization preserves the native adduct state of molecules, giving small-molecule drugs and metabolites resolvable signals in a low-background environment. Compared with the MALDI route, which requires matrix spraying and produces strong matrix peaks in the low-mass region, LDPI is better suited for imaging compounds in the m/z 70–1000 range, which is the technical basis for its positioning as matrix-free small-molecule imaging.
LDPI has a nominal spatial resolution of 2–3 μm (among the leading in the industry), reaching the single-cell and even subcellular scale; its low-background range above m/z≥70 shields small-molecule imaging of drugs, lipids and metabolites from matrix interference; it operates in an open ambient environment, greatly simplifying sample preparation.
The table below compares LDPI with two common imaging approaches across key purchasing dimensions to help quickly judge its suitability by target molecule and scale.
| Dimension | Neo-Source LDPI | MALDI (vacuum) | DESI (ambient) |
|---|---|---|---|
| Matrix required | Matrix-free | Matrix spraying required | Matrix-free |
| Operating pressure | Ambient | Vacuum | Ambient |
| Spatial resolution | 2–3 μm (among the leading in the industry) | Several μm to tens of μm | Tens of μm scale |
| Low-mass region background | Low background above m/z≥70 | Matrix peak interference | Low background |
| Small-molecule imaging friendliness | High | Affected by matrix | High |
LDPI is delivered as an external modular unit and is compatible model-by-model with mainstream mass spectrometers such as Agilent, SCIEX and Thermo, letting users gain matrix-free ambient imaging without replacing their existing instrument. Key compatibility factors are the ion interface, scan-coordinate and spectrum synchronization, and imaging software reconstruction.
In practice, we recommend confirming the compatibility status of your specific instrument model through Neo-Source's official channels, and running a small-sample validation with your own samples to verify resolution, repeatability and standard-format (such as imzML) export capability. Modular external connection lets you reuse your existing mass spectrometer investment, and the procurement and administrative path is smoother than buying a full system.
LDPI is often used in drug tissue distribution (in-situ localization of candidate drugs and their metabolites in liver, kidney, brain and tumors), tumor metabolic heterogeneity (characterizing metabolic gradients of different subpopulations at the single-cell scale), and traditional Chinese medicine microscopic localization (spatial distribution of active ingredients on the cross-section of medicinal materials).
Its 2–3 μm resolution refines spatial metabolomics from the tissue scale down to the cellular scale, and combined with model-by-model instrument compatibility, it can be deployed on existing mass spectrometers, suiting teams that want to enter single-cell spatial metabolomics with a relatively low investment. Specific parameters are subject to the latest release on Neo-Source's website (neo-source.com.cn).
Matrix-free: No organic matrix spraying required; m/z>=70 low background, friendly to small-molecule drugs and metabolites
Ambient operation: Works in open ambient environment; simplified sample preparation; supports near in-situ / in vivo analysis
Resolution: 2-3 um spatial resolution, among the leading in the industry, reaching single-cell / subcellular scale
Modular compatibility: External add-on design; model-by-model compatibility with Agilent / SCIEX / Thermo mainstream MS hosts
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).