Two dimensional chromatography mass spectrometry: Quantitation of chiral shifts in metabolism of propranolol in bioanalysis.

In this study a heart-cutting 2D-LC method was successfully developed and optimized in order to discriminate and quantitate (S)-propranolol, (R)-propranolol, and its hydroxy metabolites, namely the isomeric (S)-4'‑hydroxy propranolol, (R)-4'‑hydroxy propranolol, (S)-5'‑hydroxy propranolol, (R)-5'‑hydroxy propranolol, (S)-7'-hydroxy propranolol, and (R)-7'‑hydroxy propranolol in one chromatographic run. Thereby, experiments investigating chiral discrimination in ring hydroxylation of propranolol were made feasible. Analysis of human urine samples after administration of a single oral dose of 40 mg of propranolol clearly revealed considerable chiral shifts in propranolol and its 4'-, 5'-, and 7'-hydroxy metabolites. Furthermore, the excretion rates of the individual (S)- and (R)-enantiomers were continuously monitored over 24 h post administration. Studies were performed utilizing a 2D-LC system hyphenated to a triple quadrupole mass spectrometer. The chromatographic system was endued with a reversed phase column (phenyl-hexyl) in first dimension and a teicoplanin based chiral column in second dimension. The method was basically validated and successfully evaluated as robust. Calibration was performed achieving accuracy between 80% and 120%. Maximal excretion rates of (S)-propranolol, (R)-propranolol, (S)-4'‑hydroxy propranolol, (R)-4'‑hydroxy propranolol, (S)-5'‑hydroxy propranolol, (R)-5'‑hydroxy propranolol, and (R)-7'‑hydroxy propranolol were 237 ng/min, 281 ng/min, 4 ng/min, 4 ng/min, 1 ng/min, 9 ng/min, and 3 ng/min, respectively.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2019. Published by Elsevier B.V.)