Generation of CsI Cluster Ions for Mass Calibration in Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

A simple method was developed for the generation of cesium iodide (CsI) cluster ions up to m/z over 20,000 in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Calibration ions in both positive and negative ion modes can readily be generated from a single MALDI spot of CsI3 with 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene] malononitrile (DCTB) matrix. The major cluster ion series observed in the positive ion mode is [(CsI)nCs]+, and in the negative ion mode is [(CsI)nI]−. In both cluster series, ions spread evenly every 259.81 units. The easy method described here for the production of CsI cluster ions should be useful for MALDI MS calibrations.

Graphical AbstractCsI cluster ions up to m/z over 20,000 can be generated in MALDI MS in both positive and negative ion modes.Figure optionsDownload full-size imageDownload high-quality image (131 K)Download as PowerPoint slide