Imaging with mass spectrometry: Which ionization technique is best?

Area of Science:

• Analytical Chemistry
• Biotechnology
• Molecular Imaging

Background:

• Mass spectrometry (MS) has become a vital tool for molecular imaging of biological tissues over the last 25 years.
• Imaging MS is crucial for studying the in situ spatial distributions of various analytes.
• Early techniques like SIMS and MALDI have been augmented by newer methods.

Purpose of the Study:

• To provide an overview of ionization techniques used in imaging mass spectrometry.
• To highlight the utility and figures of merit of different MS ionization methods.
• To guide researchers in selecting appropriate techniques for their imaging MS experiments.

Main Methods:

• Review of established and emerging ionization techniques for MS imaging.
• Discussion of secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption/ionization (MALDI).
• Exploration of newer methods such as desorption electrospray ionization (DESI), nanoDESI, laser ablation electrospray ionization (LAESI), and infrared MALDI.

Main Results:

• A wide array of ionization techniques are now available for imaging mass spectrometry.
• Each technique offers distinct advantages and performance characteristics for surface analysis and MS imaging.
• The choice of technique depends on the specific analytes and substrates being investigated.

Conclusions:

• Investigators have numerous ionization techniques to choose from for imaging MS.
• Understanding the utility and figures of merit of each technique is essential for successful experiments.
• This perspective aids in selecting the optimal ionization method for diverse imaging MS applications.