Optimising LC-ESI-MS/MS for Quantitation and Pharmacokinetics of Sodium Phenylbutyrate and Taurursodiol in Rat Plasma

This study developed and validated a novel LC-ESIMS/ MS method for quantifying sodium phenylbutyrate (SPB) and taurursodiol (TSD) in rat plasma. Analytes were extracted via solvent extraction and separated using a Waters X-Bridge BEH phenyl-functionalized column (150 mm × 4.6 mm, 3.5 μm) with a mobile phase of acetonitrile and 0.1% trifluoroacetic acid in water (30:70 v/v). The method achieved separation within 5 minutes at a 1 ml/min flow rate, with SPB and TSD retention times of 2.227 and 3.333 minutes respectively. Quantitation was performed using MRM in positive ionisation mode with nitrogen as the collision gas, monitoring specific ion transitions. Linearity was observed for TSD (10–200 ppb) and SPB (30–600 ppb), with recoveries of 96.98–98.57% (TSD) and 95.22–98.59% (SPB). Intraday precision (%CV) ranged from 0.39–1.91% (SPB) and 0.85–9.03% (TSD). Pharmacokinetic parameters such as Cmax, tmax, AUC0−∞ and half-life were successfully determined. The method met FDA and EMA validation criteria, demonstrating accuracy, precision and stability. It is suitable for pharmacokinetic studies and quality control offering a reliable, reproducible and efficient tool for routine SPB and TSD analysis.