Rapid Communications in Mass Spectrometry · 1999 · 30 citations · 0 references
PharmacyPharmaceutical AnalysisPharmaceuticsAnalytical ChemistryMass Spectrometric AnalysisPharmacokinetic VariabilityBioanalytical Method ValidationInstrumental AnalysisIonization TechniquesSample PreparationConcentration Variability AnalysisElectrospray IonizationSample Preparation Method Development
The study developed a post‑column infusion system to evaluate how endogenous plasma interferences suppress electrospray ionization in tandem mass spectrometry. The system enabled direct detection of interfering components and was used to assess the effectiveness of MTBE liquid‑liquid, Oasis and Empore solid‑phase, and ACN protein precipitation sample preparations in removing plasma constituents that alter ESI response. ACN protein precipitation produced the greatest ESI suppression, liquid‑liquid extraction the least, and suppression varied with compound polarity, being highest for caffeine and lowest for the Merck compound. © 1999 John Wiley & Sons, Ltd.
A post-column infusion system was developed in order to analyze suppression of electrospray ionization (ESI) tandem mass spectrometry response in the presence of endogenous plasma interferences. By enabling direct detection of these interfering components, this experimental system was used to analyze the ability of several common extraction procedures to remove endogenous plasma components that cause changes in the ESI response of model drug substances. Methyl-t-butyl ether (MTBE) liquid-liquid, Oasis and Empore solid-phase, and acetonitrile (ACN) protein precipitation sample preparation methods were tested using the post-column infusion system. In all cases, ACN protein precipitation samples showed the greatest amount of ESI response suppression while liquid-liquid extracts demonstrated the least. In addition, the three test compounds, phenacetin, caffeine, and a representative Merck compound, demonstrated that ESI response suppression is compound dependent. Suppression was greatest with caffeine, the most polar analyte, and the smallest for the Merck compound, the least polar analyte. Copyright © 1999 John Wiley & Sons, Ltd.