An Ultra-Performance Liquid Chromatography–Tandem Mass Spectrometry Method for the Determination of Deoxycholic Acid and Application to a Pharmacokinetic Study in Human Plasma

Deoxycholic acid (DCA) injection is applied in treating moderate to severe submental bulge or facial fullness caused by excessive submental fat accumulation. Using ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) technology, which was swiftly, precisely, and reliably confirmed, DCA was determined in human plasma with low quantification limits of 56 ng/mL. We selected six healthy individual blank human plasma with low concentrations of endogenous DCA and mixed them to prepare standard curve samples. The samples were purified by the protein precipitation technique and then separated using a BEH C18 column (2.1 × 50 mm, 1.7 μm). Using multiple reaction monitoring (MRM) and electrospray ionization (ESI) sources operating in negative mode, the mass was identified and measured. The precursor-to-product ion transitions were observed at m/z 391.2⁻ → 345.2⁻ and m/z 395.2⁻ → 349.2⁻ for DCA and DCA-d₄ (isotope internal standard), respectively. This method was thoroughly validated, encompassing assessments of linearity, sensitivity, precision, selectivity, stability, matrix effect, accuracy, carryover, and recovery. In a word, the validation results demonstrated that this method exhibited sensitivity, accuracy, and reproducibility and could effectively be utilized for studying the pharmacokinetic properties of DCA in a randomized, parallel, controlled, Phase I clinical trial.