How to choose a MALDI mass spectrometry imaging matrix? What are DHB and CHCA each suited for measuring?
MALDI mass spectrometry imaging requires matrix spraying, and matrix selection directly determines which molecules can be measured: DHB suits medium-to-high mass such as proteins/peptides, CHCA suits low mass such as small molecules, lipids and peptides; for small-molecule drugs and metabolites with m/z<400, matrix peaks form background, so matrix-free sources such as LDPI/DPI should be considered for evaluation.
How to choose a MALDI mass spectrometry imaging matrix? What are DHB and CHCA each suited for measuring? — schematic diagram
1. What DHB is suited for
DHB (2,5-dihydroxybenzoic acid) has high ionization efficiency and a mass window biased toward the medium-to-high range; it is the mainstream matrix for protein and peptide imaging and is also used for some lipids and sugars; it suits kDa-level proteins and longer peptides.
High concentration or thick coating produces matrix cluster ion background in the low-mass region, interfering with small molecules.
2. What CHCA is suited for
CHCA (α-cyano-4-hydroxycinnamic acid) has fine crystals and suits small molecules, peptides, lipids and medium-to-low mass compounds; it is a common matrix for metabolite/small-molecule drug imaging and performs well in the m/z 100–1000 range.
For very small molecules with m/z<200, matrix peak interference may still occur, so concentration and spraying need to be optimized.
3. How to choose by target molecule
First look at the target molecule's mass range: proteins/peptides (>kDa) → DHB; small-molecule drugs, metabolites, lipids (100–1000) → CHCA; if low background below m/z<400 is needed, prioritize evaluating matrix-free sources such as LDPI/DPI.
Also combine with the sample and instrument: spraying uniformity, laser wavelength and whether tandem mass spectrometry is needed.
4. Practical key points
Matrix concentration, solvent (such as acetonitrile/water/TFA systems) and spraying method (pneumatic spray, sublimation or spotting) together affect crystal morphology and signal; it is recommended to use standards for small-sample optimization.
Literature and vendor methods can serve as a starting point, but the final criterion is validation with your own samples (see sample preparation requirements).
Frequently Asked Questions (FAQ)
What is the main difference between DHB and CHCA?
DHB is biased toward medium-to-high mass (proteins/peptides), CHCA toward low mass (small molecules/lipids).
Which matrix is used for small-molecule drugs?
Prioritize CHCA, but it is still subject to matrix peak interference; for low-background needs, a matrix-free source can be used.
Does the matrix affect the low-mass region?
Yes, matrix cluster ions form background below m/z<400, which is the main interference in small-molecule imaging.
How to choose concentration and spraying?
Based on the target molecule and instrument, use standards for small-sample optimization, and refer to literature and vendor methods.
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).