Matrix-free methods for laser desorption/ionization mass spectrometry.
Matrix assisted laser desorption/ionization (MALDI) is a soft ionization mass spectrometric method that has become a preeminent technique in the analysis of a wide variety of compounds including polymers and proteins. The main drawback of MALDI is that it is difficult to analyze low molecular weight compounds (<1,000 m/z) because the matrix that allows MALDI to work interferes in this mass range. In recent years there has been considerable interest in developing laser desorption/ionization (LDI) techniques for the analysis of small molecules. This review examines the approaches to matrix-free LDI mass spectrometry including desorption/ionization on silicon (DIOS), sol-gels, and carbon-based microstructures. For the purposes of this review matrix-free methods are defined as those that do not require matrix to be mixed with the analyte and therefore does not require co-crystallization. The review will also examine mechanisms of ionization and applications of matrix-free LDI-MS.
Peterson
Dominic S
DS
Los Alamos National Laboratory, Chemistry Division, Mailstop K484, Los Alamos, New Mexico 87545, USA. DominicP@lanl.gov
D013048:Specimen Handling / Q000379:methods* / Q000639:trends*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods* / Q000639:trends*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods* / Q000639:trends*