Recent Progress of Two-step Laser Desorption/Laser Ionization Mass Spectrometry and its Application

As a particular ionization technique, laser photoionization has been widely used in mass spectroscopy. Matrix-assisted laser desorption ionization (MALDI), in which only one laser was used, has become the standard method in the biological mass spectrometry. In this review, a novel mass spectrometry is introduced, i.e., two-step laser desorption/laser ionization mass spectrometry (L2MS). In comparison with MALDI, no matrix is needed to add on the substrate to form a good cocrystallization with sample molecules. The signal can be optimized by changing the power and wavelength of two lasers independently. In this article, we review the recent research progress on L2MS and its applications on the analysis of amino acids and peptides, environmental pollutants such as polycyclic aromatic hydrocarbons, chemical additives, mineral composition, metabolic products, and so on. Future prospect in this field is provided in the end of this article.