Scope and Limitation of Matrix-Assisted Laser Desorption/Ionization Fourier Transform Mass Spectrometry for Testing the Complexing Behavior of Two Crown Ethers Derived from D-Hexopyranosides

Abstract

The complexing abilities of two macrocycles, namely a 18-C-6 crown ether (CE1) and a 20-C-6 crown ether (CE2) towards one organic guest [protonated phenethylamine (PEAH+)], were investigated with help of matrix-assisted laser desorption/ionization (MALDI) Fourier transform mass spectrometry. A qualitative correlation between the complexation behavior of CE1 in solution and in the gas phase of the spectrometer could be established. We concluded from these results that a fine control of laser irradiance and the use of a suitable sample protocol allowed the preservation of weak molecular interactions throughout the MALDI process. The observed positive ions can be considered as being already present in the deposited solid solution and merely liberated by the laser pulse.