MALDI mass spectrometry using 2,4,6-trihydroxyacetophenone and 2,4-dihydroxyacetophenone with cyclodextrins: suppression of matrix-related ions in low-molecular-weight region.

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry of a model peptide, Substance P (SubP), was carried out using 2,4,6-trihydroxyacetophenone (THAP) and 2,4-dihydroxyacetophenone (DHAP) with cyclodextrins (cyclodextrin-supported matrix). It was found that the use of a cyclodextrin-supported matrix simplified the mass spectrum in the low-molecular-weight region. The interaction between THAP/DHAP and cyclodextrin (CD) was studied by UV-vis absorption spectroscopy and the incorporation of matrix molecules into the cyclodextrin cavity was confirmed by (1)H-NMR spectroscopy. DHAP showed tight incorporation with betaCD (betaCD(DHAP)) rather than THAP and it was found that the matrix-related peaks could be weakened by less than one third of the peak intensity of a protonated analyte. The betaCD(DHAP) matrix was applied to the measurements of two low-molecular-weight compounds; adenosine and adrenaline. It became clear that the cyclic structure of the CD and the host-guest interaction between betaCD and the matrix molecule were important to reduce the matrix-related peaks of THAP and DHAP.