ANALYSIS OF CYCLOMALTOOLIGOSACCHARIDES (CYCLODEXTRINS) AND DERIVATIVES THEREOF BY ION-SPRAY MASS-SPECTROMETRY

The use of ion-spray (i.s.) mass spectrometry for the rapid determination of molecular weight and purity is demonstrated for derivatives of cyclomalto-hexaose (alpha-CD), -heptaose (beta-CD), and -octaose (gamma-CD), and for beta-CD. The i.s.-mass spectra contain peaks for singly and doubly charged protonated and cationised quasi-molecular ions- Methylation of CDs yielded homogeneous compounds, whereas the synthesis of CDs containing methyl groups and an additional substituent, e.g., allyl, pentenyl, octenyl, trifluoroacetyl, or heptafluorobutanoyl, afforded mixtures of products, the compositions of which could be determined directly from the i.s.-mass spectra. The addition of lithium chloride usually facilitated the interpretation of the spectra by producing abundant (M + Li)+ ions and suppressing fragmentation. Zinc acetate favoured the formation of doubly charged molecular ions. Additional information on the structure of derivatised CDs can be obtained by i.s.-tandem mass spectrometry.