On the specificity of cyclodextrin complexes detected by electrospray mass spectrometry

Abstract

Alpha-cyclodextrin complexes with linear alpha,omega-dicarboxylic acids were investigated by electrospray mass spectrometry. These hydrophobic complexes are known to have an equilibrium binding constant that increases with the diacid chain length. However, the electrospray mass spectrometry (ES-MS) spectra showed that the relative intensity of the complex did not vary significantly with chain length. This contradiction is caused by a contribution of nonspecific adducts to the signal of the complex in ES-MS. In order to estimate the contribution of nonspecific adducts to the total intensity of the complexes with alpha-cyclodextrin, the comparison was made between alpha-cyclodextrin and maltohexaose, the latter being incapable of making inclusion complexes in solution. The signal observed for complexes between diacids and maltohexaose can only result from nonspecific electrostatic aggregation, and is found to be more favorable with the shorter diacids. This is also supported by MS/MS experiments. A procedure is described which allows estimation of the contribution of the nonspecific complex in the spectra of the complexes with alpha-cyclodextrin by using the relative intensity of the complex with maltohexaose. The contribution of the specific complex to the total signal intensity is found to increase with the diacid chain length, which is in agreement with solution behavior.

Journal

Title: Journal of the American Society for Mass Spectrometry

Abbreviated Title: J Am Soc Mass Spectrom

Publisher: Elsevier BV

ISSN (Print): 1044-0305

ISSN (Electronic): 1879-1123

Publication date Created: August 2002

Publication date (Print): August 2002

Volume: 13

Issue: 8

Pages: 946-953

Article

DOI: 10.1016/S1044-0305(02)00416-6

PubMed ID: 12216735

Copyright statement: © 2002

Product

Self URI (article page): https://pubs.acs.org/doi/10.1021/jasms.8b01826