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 language | English |
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Pages (from-to) | 1231-1234 |
Number of pages | 4 |
Journal | Journal of Pharmaceutical and Biomedical Analysis |
Volume | 40 |
Issue number | 5 |
DOIs | |
Publication status | Published - 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