Simultaneous determination of tenidap and its stable isotope analog in serum by high‐performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry

A specific high‐performance liquid chromatographic/atmospheric pressure chemical ionization tandem mass spectrometric assay for the quantitative determination of tenidap and its D3 analog in human serum is described. The assay exhibited a linear dynamic range of 0.1‐25 μg ml−1. Its precision for the two analytes over the range was 17% or better. The assay validity and its utility to investigate changes in tenidap bioequivalence and pharmacokinetics are presented.