Liquid chromatography/tandem mass spectrometric bioanalysis using normal-phase columns with aqueous/organic mobile phases - a novel approach of eliminating evaporation and reconstitution steps in 96-well SPE

Rapid Commun Mass Spectrom. 2002;16(20):1965-75. doi: 10.1002/rcm.817.

Abstract

Bioanalytical methods using automated 96-well solid-phase extraction (SPE) and liquid chromatography with electrospray tandem mass spectrometry (LC/MS/MS) are widely used in the pharmaceutical industry. SPE methods typically require manual steps of drying of the eluates and reconstituting of the analytes with a suitable injection solvent possessing elution strength weaker than the mobile phase. In this study, we demonstrated a novel approach of eliminating these two steps in 96-well SPE by using normal-phase LC/MS/MS methods with low aqueous/high organic mobile phases, which consisted of 70-95% organic solvent, 5-30% water, and small amount of volatile acid or buffer. While the commonly used SPE elution solvents (i.e. acetonitrile and methanol) have stronger elution strength than a mobile phase on reversed-phase chromatography, they are weaker elution solvents than a mobile phase for normal-phase LC/MS/MS and therefore can be injected directly. Analytical methods for a range of polar pharmaceutical compounds, namely, omeprazole, metoprolol, fexofenadine, pseudoephedrine as well as rifampin and its metabolite 25-desacetyl-rifampin, in biological fluids, were developed and optimized based on the foregoing principles. As a result of the time saving, a batch of 96 samples could be processed in one hour. These bioanalytical LC/MS/MS methods were validated according to "Guidance for Industry - Bioanalytical Method Validation" recommended by the Food and Drug Administration (FDA) of the United States.

MeSH terms

  • Adrenergic beta-Antagonists / analysis
  • Adrenergic beta-Antagonists / blood
  • Bronchodilator Agents / analysis
  • Bronchodilator Agents / blood
  • Chromatography, Liquid
  • Ephedrine / analysis
  • Ephedrine / blood
  • Histamine H1 Antagonists / analysis
  • Histamine H1 Antagonists / blood
  • Humans
  • Leprostatic Agents / analysis
  • Leprostatic Agents / blood
  • Metoprolol / analysis
  • Metoprolol / blood
  • Pharmaceutical Preparations / analysis*
  • Quality Control
  • Reproducibility of Results
  • Rifampin / analysis
  • Rifampin / blood
  • Robotics
  • Solvents
  • Spectrometry, Mass, Electrospray Ionization
  • Terfenadine / analogs & derivatives*
  • Terfenadine / analysis
  • Terfenadine / blood

Substances

  • Adrenergic beta-Antagonists
  • Bronchodilator Agents
  • Histamine H1 Antagonists
  • Leprostatic Agents
  • Pharmaceutical Preparations
  • Solvents
  • Terfenadine
  • fexofenadine
  • Metoprolol
  • Ephedrine
  • Rifampin