Impact of Sample Preparation on Chiral SFC-MS/MS Analysis of Propranolol and Its Hydroxy Metabolites in Human Urine

In this study, chiral separation and mass spectrometric detection of propranolol and its hydroxy metabolites, 4',5', and 7'-hydroxypropranolol, were performed by supercritical fluid chromatography hyphenated via electrospray ionization to tandem mass spectrometry (SFC-ESI-MS/MS). Four different sample preparation methods were applied to urine samples from an excretion study after a single oral dose of 40 mg propranolol. The methods employed were dilute and inject, liquid-liquid extraction, hydrophilic-lipophilic balanced-based, and mixed-mode cation exchanger-based solid-phase extraction. For the evaluation of the sample preparation methods, the matrix effect and recovery results were taken into consideration. Furthermore, as part of extensive troubleshooting for the poor detectability of 4'hydroxypropranolol from matrix samples, post-column infusion experiments were performed, and the matrix profiles were discussed. Liquid-liquid extraction and hydrophilic-lipophilic balanced-based solidphase extraction gave the best overall results for quantitative matrix effect, recovery, and matrix profiles. Dilute and inject suffered from significant ion suppression. However, the major unsolved problem was a loss of sensitivity for signals of (R)-and (S)-4'-hydroxypropranolol.