Carbon nanotubes as assisted matrix for fullerenes

Abstract

Matrix-assisted laser desorption/ionization (MALDI) coupled with reflectron time-off-light mass spectrometry was applied to the analysis of fullerenes (C-60 and C-70). This investigation included the screening of three different compounds regarding their suitability as MALDI matrices. It has been found that the performance of alpha-cyano-4-hydroxycinnamic acid (CHCA), currently one of the most universally used matrices in MALDI analyses, is exceeded by some of these materials. In the negative ion-mode, excellent performance has been achieved using 2-[(2E)-3-(4-tertbutylphenyl)-2-methylprop-2-enylidene] malonitrile (DCTB). These matrixes should efficiently absorb at commonly used laser wavelength (typically for a 337-nm nitrogen laser) and form homogeneous microcrystalline solids with analyte molecules. The soft ionization technique affords little to no fragmentation of analyte. Carbon nanotubes, prepared by an are discharge method, were investigated as the third matrix. It was observed that the carbon nanotube layer as a matrix provides high detection sensitivity and mass resolution of fullerenes with eliminating matrix ion interference.