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Eur. J. Mass Spectrom. 3, 141 - 149 (1997) |
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Ultraviolet laser desorption ionisation mass spectrometry of selected calixarenes with and without matrix assistance | ||
Katharina Linnemayr and Günter Allmaier* |
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ABSTRACT: | ||
Ultraviolet (UV) matrix-assisted laser desorption/ionisation (MALDI) and laser desorption/ionisation (LDI) mass spectrometry have been applied to study the macrocyclic, basket-like compound class of calixarenes for rapid characterisation. Three different types of cyclic oligomeric alkyl phenolsunderivatised calixarenes and calixarenes carrying one or several acyl moieties as additional functional groups, as well as so-called resorcinareneshave been investigated. It is shown that relative molecular mass determination of nitrogen-free calixarenes is possible by detecting alkali adduct ions in the positive-ion mode and sometimes deprotonated molecular ions in the negative-ion mode by both MALDI and LDI. Best results with the MALDI technique have been obtained with the matrices a-cyano-4-hydroxy-cinnamic acid and 3-hydroxypicolinic acid. Depending on the applied laser energy, fragmentation can be induced to some degree in MALDI as well as LDI. Since positive-ion MALDI mass spectrometry gave mainly sodiated molecular ions for the selected calixarenes, post source decay (PSD) experiments were carried out applying a coaxial curved-field reflectron in order to generate fragment ions. The positive-ion PSD spectra contained diagnostic fragment ions, which enabled, to some extent, the kind and number of ester or ether groups on the hydrophilic rim of the bowl-shaped macrocyclic compound to be established unambiguously. | ||
Keywords: Calixarene, resorcinarene, macrocycle, UV MALDI, UV LDI,mass spectrometry, post source decay, fragmentation, positive ion mode, negative ion mode. |
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