Postcolumn Infusion of Labeled Racemic Chiral Selector Enables LC-Chiral MS/MS

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Metabolomics

Background:

• Accurate enantiomeric excess (ee) determination is crucial for analyzing chiral compounds in complex matrices.
• Existing methods for chiral analysis often require separate steps for chiral recognition, chiral selector (CS) screening, and ee determination.
• Developing a unified approach for these tasks can significantly streamline chiral metabolomics research.

Purpose of the Study:

• To develop a single pipeline for chiral recognition, CS screening, and ee determination using LC-MS/MS.
• To enable the measurement of enantiomers in complex biological samples.
• To establish a versatile tool for chiral metabolomics, even for metabolites lacking specific functional groups.

Main Methods:

• Utilized postcolumn infusion (PCI) of a labeled racemic chiral selector (dl-Phe) in the presence of Cu²⁺.
• Generated diastereomeric trimeric cluster ions from enantiomers, enabling chiral MS/MS analysis based on differential dissociation kinetics.
• Employed full collision energy ramp (FCER)-MS² spectra for chiral recognition and correlated ion intensities with thermal enthalpy.

Main Results:

• Successfully achieved chiral recognition of angular-type pyranocoumarin (AP) enantiomers from Peucedani Radix (PR).
• Screened 15 APs as potential chiral selectors based on complex formation and distinct dissociation patterns.
• Demonstrated simultaneous ee determination of amino acids (AAs) in tea samples and APs in PR using the developed method.

Conclusions:

• The integration of labeled racemic CS and PCI-LC-MS/MS provides a 'three birds with one stone' solution for enantiomeric measurements.
• This method offers a versatile and efficient tool for chiral metabolomics, applicable to a wide range of metabolites.
• The approach facilitates the identification of enantiomers as key differential variables in metabolomic studies.