ω-Iodoalkylammonium salts as permanent capillary silica wall modifiers: Comparative analysis of their structural parameters and substituent effects

Roberto Sebastiano, Cecilia Gelfi, Pier Giorgio Righetti, Attilio Citterio

Research output: Contribution to journalArticlepeer-review

Abstract

Following previous work on the modification and inversion of electroendoosmotic flow (EOF) of naked silica by a cyclic diamine [1-(4-iodobutyl)-1,4-dimethylpiperazin-1-ium iodide] [J. Chromatogr. A 894 (2000) 53], the present report considerably expands previous data by describing additional compounds of the same series of ω-iodoalkylammonium salts. Four of them are able to instantaneously reverse the EOF, thus producing a cationic surface with a highly stable reverse EOF. All these compounds are believed to become covalently attached to the silica surface via alkylation occurring by nucleophilic substitution of ionized silanols on the silica wall by the ω-iodo functionality in the modifier. The unique advantage of such compounds, as compared to adsorbed polymers or oligoamine EOF quenchers, is that they are not needed any longer in the background electrolyte, after the initial conditioning step inducing the covalent bond. It is additionally demonstrated, by running a mixture of cinnamic acid compounds, that some of the ω-iodoalkylammonium salts can act as modulators of analyte migration, thus inducing separations of otherwise identical compounds, such as isomeric species. Such interactions can only occur when the analytes drift close to the silica wall, and must be rapidly reversible, since no peak tailing or broadening is experienced.

Original languageEnglish
Pages (from-to)71-81
Number of pages11
JournalJournal of Chromatography A
Volume924
Issue number1-2
DOIs
Publication statusPublished - Jul 27 2001

Keywords

  • Capillary columns
  • Cinnamic acid
  • Electroosmotic flow
  • Iodoalkylammonium salts

ASJC Scopus subject areas

  • Analytical Chemistry

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