Imaging mass spectrometry with MALDI

The preparation of samples for mass spectrometric analysis almost always requires recovery of the analyte from a matrix, often followed by further preparative steps prior to introduction of the sample into the ion source. Such destructive processes are unacceptable when the objective is to determine the specific location of a particular compound within a biological sample, e.g., the location of a certain lipid in a tissue, and led to the development of imaging mass spectrometry with MALDI as the ionization method, although DESI is also applicable. 

Baluya D, Garrett T, Yost R (2007) Automated MALDI matrix deposition method with inkjet printing for imaging mass spectrometry. Anal Chem 79 6862-6867. doi 10.1021/ac070958d... 

Solid samples can be analyzed by mass spectrometry with techniques providing ionization by desorption (13) such as MALDI (matrix assisted laser desorption ionization) (14) and S-SIMS (static-secondary ion mass spectrometry) (15). Ions are produced by energy deposition on the sample surface. The analysis can be performed at the bead level. Most of all, chemical images can be produced to localize specific compounds on the studied surfaces. 

Figure 8.1. MALDI imaging mass spectrometry process. Reprinted from reference 42 with permission from Elsevier (See color insert).

A modified version of 2DE and gel image analysis, with silver staining, autoradiography, and protein identification and measurement of peptide mass, uses matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) as a rapid and sensitive technique for identifying peptides. MALDI-TOF-MS applies well to protein detection in biological fluids.56 A second advantage of this technique is... 

Imaging with Laser Microprobes and MALDI Mass Spectrometry... 

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