Ionization of unconjugated, glycine- and taurine-conjugated bile acids by electrospray ionization mass spectrometry

Nariyasu Mano, Masaru Mori, Masayuki Ando, Takaaki Goto, Junichi Goto

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

We investigated the effect of organic anions as spray liquid additives on the ionization efficiency of unconjugated, glycine-conjugated and taurine-conjugated bile acids under electrospray ionization conditions. Addition of organic acids influenced the ionization efficiency of whole bile acids. Use of a stronger acid reduced the peak intensity of unconjugated and glycine-conjugated bile acids, while the use of TFA, the strongest acid tested, improved the intensity of taurine conjugates. The hydroxyl group at the C-12α position of cholic acid and deoxycholic acid easily underwent intra-molecular hydrogen bonding with the side chain carboxyl group, accelerating the ionization efficiency. This intra-molecular hydrogen bond may also affect the formation of product ions in low energy-CID. The addition of ammonium ions to the spray liquid influenced the ionization of all bile acids, specifically enhancing the ionization efficiency of unconjugated bile acids.

Original languageEnglish
Pages (from-to)1231-1234
Number of pages4
JournalJournal of Pharmaceutical and Biomedical Analysis
Volume40
Issue number5
DOIs
Publication statusPublished - 2006 Mar 18

Keywords

  • Bile acid
  • CID
  • ESI
  • Intra-molecular hydrogen bonding
  • Ionization efficiency

ASJC Scopus subject areas

  • Analytical Chemistry
  • Pharmaceutical Science
  • Drug Discovery
  • Spectroscopy
  • Clinical Biochemistry

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