Laser desorption/ionization mass spectrometric analysis of folic acid, vancomycin and Triton® X-100 on variously functionalized carbon nanotubes

Abstract

RATIONALE Carbon nanotubes (CNTs) have been ascertained to constitute versatile assisting matrices for laser desorption/ionization mass spectrometric analysis of different molecules. The functionalization thereof can lead to obtaining laser desorption/ionization assisting surfaces that would allow the detection of molecules at lower concentration and produce spectra with a better signal-to-noise ratio. METHODS Pristine, -OH and -COOH functionalized multi-walled CNTs were obtained from commercial suppliers. Gallic or sinapinic acid was attached covalently to the CNT surfaces by forming an ester bond. Folic acid, vancomycin and Triton® X-100 were used as analytes to examine properties of these new assisting surfaces. Mass spectrometry analysis was conducted on a matrix-assisted laser desorption/ionization quadrupole time-of-flight (MALDIQTOF) mass spectrometer. RESULTS The functionalization of CNTs was confirmed with Fourier transform infrared (FTIR) spectroscopy. The obtained mass spectra revealed that all the assisting surfaces are capable of transferring energy to the analytes; moreover, the presence of carboxyl groups in the structures of CNTs highly enhances their ionization properties. Nevertheless, the presence of sinapinic acid on CNT surfaces does not increase their properties to absorb pulse laser energy. CONCLUSIONS The presented assisting surfaces are effective in LDI mass analysis of folic acid, vancomycin and Triton® X-100. The appropriate functionalization of CNTs can lead to the production of assisting surfaces that can become highly effective in the ionization of particular types of analytes. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.