Reactive Matrices for Analytical Matrix-Assisted Laser Desorption/Ionization (MALDI) Mass Spectrometry

Abstract

In recent years, a special focus is placed on the usage of reactive matrices for analytical matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS). Since 2003, when the term “reactive matrices” was suggested and the dignity of compounds, possessing dualistic properties as matrices and derivatization agents was demonstrated, corresponding approach has found application in various fields and, in particular, in bioanalysis (metabolomics, lipidomics, etc.). The main advantage of this methodology is that it reduces sample treatment time, simplifies the procedure of sample handling, improves the sensitivity of analysis, enhances the molecular identification and profiling. Within the framework of this review, the main attention is paid to “true” reactive matrices that interact with analyte molecules through an exchange or addition reactions. A special section discusses practical application of reactive matrices in the determination of the distribution of targeted and non-targeted organic substances on the surface of biological tissue sections by MALDI-MS imaging. In this critical review, a controversial proposal is made to consider protonating and deprotonating matrices as reactive, because they can undergo a chemical reaction such as proton transfer that occurs in both target solution and MALDI plume. In this respect, special attention is paid to “proton sponge” matrices that have found a wide application in the analysis of various acidic compounds by MALDI-MS in the negative mode. Historical data on the formation of ions and the fate of matrices in MALDI are considered at the beginning of this article.

Keywords:

• MALDI mass spectrometry
• MALDI mass spectrometry imaging
• metabolomics
• reactive matrices

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The review was funded by the Russian Foundation for Basic Research (RFBR; Project No. 19-33-60037). The analysis of application of reactive matrixes for analysis of thiols was carried out within the state assignment of A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences.