Mercaptobenzothiazoles: A new class of matrices for laser desorption ionization mass spectrometry

We report 2-mercaptobenzothiazole (MBT) and its analogs as a class of new matrices for matrix-assisted laser desorption mass spectrometry (MALDI-MS) at 337 nm. MBT has been used successfully for the desorption of proteins up to 100,000 u. A comparison with sinapinic acid and alpha-cyano-4-hydroxycinnamic acid indicates that MBT provides the same level of sensitivity and resolution, but offers the advantage of higher tolerance to sample contaminants such as ionic detergents. 5-Chloro-2-mercaptobenzothiazole (CMBT), an analog of MBT, has been found not only effective for the analysis of peptides, low-mass proteins, and glycolipids, but also superior to conventional matrices for the analysis of muropeptides and at least some oligosaccharides. CMBT also exhibits excellent experimental reproducibility of MALDI-MS results owing to the homogeneous crystallization of the analyte/matrix mixture over the entire sample surface area. Finally, all five mercaptobenzothiazoles studied in this work are shown to be well suited for synthetic polymer analysis. (C) 1997 American Society for Mass Spectrometry