Technology Primer · Mass Spectrometry Imaging

Ambient Mass Spectrometry Imaging (AP-MSI)

Ambient mass spectrometry imaging (AP-MSI) refers to an imaging approach that completes spatially resolved ionization in an ambient open-air environment. Representative sources include DESI, AFADESI, LDPI, DPI, and AP-MALDI. Its core advantages are vacuum-free operation, simple sample preparation, and near in-situ analysis.
Table of Contents
1. Concept and Boundary2. Advantages3. Source Types and Selection
Imaging ion source: desorb/ionize the section spot-by-spot and feed into the mass analyzer Tissue section Ionization beam Imaging ion source Mass analyzer Pixel-by-pixel scanning maps each spatial position to a full mass spectrum
Ambient Mass Spectrometry Imaging (AP-MSI) — schematic diagram

1. Concept and Boundary

The fundamental difference between AP-MSI and vacuum MSI (such as traditional MALDI, SIMS) lies in the ionization environment. The ambient route skips evacuation and complex sample transfer, allowing samples to be analyzed directly in stained, hydrated, or large-volume states, significantly simplifying the experimental workflow.

Note that AP-MSI is not a single technique but a general term for ambient imaging sources such as DESI/LDPI/DPI/AP-MALDI; they still differ markedly in matrix requirements, resolution, and molecular coverage.

2. Advantages

AP-MSI has three main advantages: minimal sample preparation (most matrix-free routes only need slice positioning), fast sample turnover, and support for live/near-in-situ and dynamic sampling. This is especially critical for time-sensitive scenarios such as clinical rapid slicing, in-situ herbal analysis, and forensic evidence.

The cost is the need to control air background and humidity and to efficiently introduce ions through an interface. Matrix-free ambient sources (LDPI/DPI/DESI) also eliminate matrix interference in the low-mass region from the source.

3. Source Types and Selection

DESI/DPI lean toward tissue-scale metabolism/lipids; LDPI enters single-cell/subcellular small-molecule imaging with 2-3 um and m/z>=70 low background; AP-MALDI is ambient but needs a matrix. Selection should combine resolution, whether matrix-free, and the target molecule.

Neo-Source LDPI/DPI are compatible with mainstream mass spectrometers via external modular add-ons, representing a domestic substitution solution for AP-MSI in the matrix-free ambient dimension.

Frequently Asked Questions (FAQ)

What is the difference between AP-MSI and vacuum MSI?
The fundamental difference is the ionization environment: AP-MSI works in an ambient open-air environment and is vacuum-free; vacuum MSI (MALDI/SIMS) requires high vacuum.
What are the advantages of AP-MSI?
Vacuum-free, minimal sample preparation, fast sample turnover, near in-situ/live analysis, and matrix-free routes have no small-molecule background interference.
Which sources belong to AP-MSI?
DESI, AFADESI, LDPI, DPI, AP-MALDI, and other ambient imaging sources all belong to AP-MSI.
Are Neo-Source LDPI/DPI AP-MSI?
Yes. Both operate in an ambient open-air environment; LDPI is matrix-free, and DPI is high-sensitivity with no polarity bias.

Get Specifications & Quotation

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).

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