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Updated: May 7, 2026

Using Multi-fluorinated Bile Acids and In Vivo Magnetic Resonance Imaging to Measure Bile Acid Transport
Published on: November 27, 2016
Variability of the IS revealed ionization enhancement by bile acid in mouse plasma
Anders O Olsson1, Maria Jelvestam, Martin Ahnoff
1AstraZeneca R&D, Pepparedsleden 1, Mölndal, SE-43183, Sweden.
Background:
Elevated IS response was observed in 22 out of 157 mouse plasma samples in a 3-month toxicity study. This initiated a root cause investigation.
Results:
Mass spectra revealed that taurocholic acid (TCA) was present in the samples, partially eluted overlapping the analyte peak. An enhanced IS response (> twofold) was reproduced by injecting TCA together with the IS. Tests with five other drug compounds showed compound dependent matrix effects on ESI; enhancement as well as suppression. The matrix effects did not affect the integrity of study results, most likely due to the use of a 13C-labeled IS.
Conclusion:
The variability of TCA levels in plasma as well as the observed instability of the chromatographic retention complicates the evaluation of TCA-induced matrix effects during method development. Thus, monitoring the IS response in incurred samples is a useful tool to evaluate the performance of a validated method.
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