y-Cyclodextrin, maltosyl-a-cyclodextrin and diglucosyl-a-cyclodextrin were analyzed using matrix-assisted laser desorptiodionization timesf-flight (MALDI-TOF) mass spectrometry. AU of these compounds have the same molecular weight (M.W.=1297.15) and consist of only ~-gIucopyrmose. From a comparison of the intensities in the post-source decay (PSD) fragment spectra of these cyclodextrin derivatives, correlation between the chemical structures and the relative intensities in the PSD fragment ions was found. The correlation is considered to be caused by the difference in the number of cleavage sites at the glycosyl binding. It was found that the intensity of the PSD ion resulting from one cleavage is higher than that resuiting from two clenvages at a glycosyl bond.
The results show that PSD fragment-ion spectrum method used in MALDI-TOF mass spectrometry is a very powerful technique for the structural analyses of the sugar-substituted cyclodextrins.
Cyclodextrins are well known host molecules in inclusion chemistry. However, their solubility is rather poor in some solvents. Many branched cyclodextrins have been synthesized to increase their solubility, not only in aqueous solvents but also in organic solvents. The chemical structures of these synthetic branched cyclodextrins were usually checked with N M R spectroscopy,' mass spectrometry, and gas-chromatography after methylation. In these analyses, it sometimes happens that the characterization of G 2 -a-CD similar molecules (structural isomers), such as maltosyl-acyclodextrin (G2-a-CD), and diglucosyl-a-cyclodextrin (Gl, G1-a-CD), is very difficult, because these two branched cyclodextrins have the same molecular weight as well as the same a-1 ,&linkage as the branch connection and the same a-1,Clinkage in the cyclodextrin and maltosyl residues (see structures 1 and 2).
Recently, analysis of cyclodextrins has been made using matrix-assisted laser desorption/ionization (MALDI) time-Gl, 01-a-CD