Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) with inorganic nanoparticles as desorption/ionization (DI) assisting materials, has been reported in order to decrease the background noises including matrix ions or matrix degradation products, especially in the region of < 500 Da. In this mass region, we can detect the existence of medical material components, drugs, and bio-related organic compounds. However, the mechanism of desorp-tion / ionization of SALDI-MS is not clear. Therefore, in order to understand the correlation of desorption/ionization efficiency with molecular structures of analytes, the efficiencies of 20 common amino acids in SALDI-MS with TiO2
nanoparticles are collected in positive ion mode. SALDI-MS with TiO2
nanoparticles gives sodium ion adducted mass peaks. The ion intensity of amino acids is mainly determined by the same factors regardless of the desorption/ionization method in both MALDI and proton adducted SALDI but poorer linear correlation between the ion yield and the sodium ion affinity was found in our system.
Key words: mass spectroscopy, surface-assisted laser desorption ionization, titanium oxide, nanoparticle
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