Matrix- and surface-assisted laser desorption/ionization time-of-flight mass spectrometry of dibromocalix[4]crown ether

Laser desorption/ionization mass spectrometry (LDI-MS) has been investigate d for dibromocalix[4]crown ether, a compound known to undergo prompt dissoc iation in excited electronic states. As a result of direct absorption by th e analyte, a considerable proportion of fragment ions were observed in tire UV matrix-assisted LDI mass spectrum. This would make it difficult to stud y host-guest complexation by this crown ether using matrix-assisted laser d esorption/ionization (MALDI) mass spectrometry. However, the molecular ion peak is largely dominant without the debrominated ions in the LDI mass spec trum obtained using visible laser radiation with a graphite plate as a phot on-absorbing material. This mass spectrum shows good signal-to-noise ratio, with a high spot-to-spot reproducibility, reflecting homogeneous sample di stribution on the graphite plate. This study suggests that use of a visible laser for LDI with a graphite plate could provide advantages for macromole cules with general transparency within the visible region. Copyright (C) 20 01 John Wiley & Sons, Ltd.