Chaotropic salts: Novel modifiers for the capillary electrophoretic analysis of benzodiazepines

Hsiu Li Su, Min Tsu Lan, Kuan Wen Lin, You-Zung Hsieh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

This paper describes a CE method for analyzing benzodiazepines using the chaotropic salts lithium trifluoromethanesulfonate (LiOTf), lithium hexafluorophosphate (LiPF 6), and lithium bis(trifluoromethanesulfonyl)imide (LiNTf 2) as modifiers in the running buffer. Although adequate resolution of seven benzodiazepine analytes occurred under the influence of each of the chaotropic anions, the separation efficiency was highest when bis(trifluoromethanesulfonyl)imide (Tf 2N -) was the modifier. We applied affinity CE in conjunction with linear analysis to determine the association constants for the formation of complexes between the Tf 2N - anion and the benzodiazepines. According to the estimated Gibbs free energies, the interactions between this chaotropic anion and the benzodiazepines were either ion-dipole or ion-induced dipole interactions. Adding chaotropic salts as modifiers into CE buffers is a simple and reproducible technique for separating benzodiazepines.

Original languageEnglish
Pages (from-to)3384-3390
Number of pages7
JournalElectrophoresis
Volume29
Issue number16 SPEC. ISS.
DOIs
StatePublished - 1 Aug 2008

Keywords

  • Affinity capillary electrophoresis
  • Benzodiazepine
  • Capillary electrophoresis
  • Chaotropic salt
  • Ionic liquid

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