Probe for label-free quantitative analysis in liquid chromatography/mass spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Pharmacokinetics

Background:

• Ion suppression is a common challenge in liquid chromatography-mass spectrometry (LC/MS), affecting quantitative accuracy.
• Existing methods for detecting ion suppression are often limited to specific liquid chromatography (LC) mobile phase conditions, particularly those used in proteomics.

Purpose of the Study:

• To evaluate the applicability of a previously developed probe molecule for detecting ion suppression under experimental conditions relevant to pharmacokinetics and drug metabolism.
• To expand the utility of the probe molecule beyond the limited LC mobile phase conditions previously established for proteomics.

Main Methods:

• A probe molecule, designed to be acidic and hydrophilic, was added to the LC mobile phase.
• The intensity of the protonated probe was monitored via mass spectrometry to detect ion suppression.
• The probe's performance was tested across a broad pH range (1.8–6.7) and organic solvent concentrations (10–90%).
• Ion suppression was demonstrated in the analysis of Omeprazole in human plasma by varying plasma concentration.

Main Results:

• The probe molecule demonstrated effectiveness in detecting ion suppression across a wide range of mobile phase pH and organic solvent concentrations.
• The probe is applicable to LC mobile phases used in pharmacokinetics and drug metabolism studies.
• Ion suppression was successfully detected during the analysis of Omeprazole in human plasma samples.

Conclusions:

• The developed probe molecule is a versatile tool for detecting ion suppression in LC/MS analyses relevant to pharmacokinetics and drug metabolism.
• This technique enhances the reliability of quantitative LC/MS by providing a real-time assessment of ion suppression.
• The probe's broad applicability expands its use in various analytical workflows.