LC/MS Based Characterization Workflow of GLP-1 Therapeutic Peptide Liraglutide and Its Impurities

Significance of the Topic

The characterization of therapeutic peptides and their low-level impurities is critical for ensuring safety and efficacy in biopharmaceutical development. GLP-1 receptor agonists, such as liraglutide, play a major role in diabetes and metabolic disorder treatments, and regulatory agencies require rigorous impurity profiling to meet strict safety thresholds.

Objectives and Study Overview

This application note presents an LC/Q-TOF MS workflow using the Agilent 1290 Infinity II LC with an AdvanceBio Peptide Plus column coupled to the Agilent 6545XT AdvanceBio LC/Q-TOF mass spectrometer. The goal is to achieve sequence confirmation of liraglutide and to identify and quantify synthesis-related impurities through an integrated MassHunter BioConfirm software peptide mapping process.

Methodology and Instrumentation

A reversed-phase gradient separation was performed on an AdvanceBio Peptide Plus column (2.1×150 mm, 2.7 µm) at 45 °C using 0.01% TFA in water/acetonitrile mobile phases. The LC system (Agilent 1290 Infinity II) was configured with a high-speed pump, multisampler, and column thermostat, and coupled to an Agilent 6545XT AdvanceBio LC/Q-TOF with Dual Jet Stream ESI source.
Key mass spectrometry parameters included extended dynamic range acquisition (2 GHz), mass range m/z 300–3200, top-3 MS/MS selection, dynamic exclusion, and accurate mass measurements.

Instrumentation Used

• Agilent 1290 Infinity II LC System (pump, multisampler, multicolumn thermostat)
• AdvanceBio Peptide Plus column (2.1×150 mm, 2.7 µm)
• Agilent 6545XT AdvanceBio LC/Q-TOF with Dual Jet Stream ESI
• Agilent MassHunter Acquisition v11.1 and BioConfirm v12.1 software

Results and Discussion

The workflow successfully separated intact liraglutide and over twenty low-level impurities, including amino acid deletions and deamidation variants. Mass errors remained below 5 ppm across charge states from +2 to +6, and isotopic fidelity confirmed the integrity of the main sequence. MS/MS fragmentation mapping of b and y ion series facilitated precise localization of sequence deletions (e.g., missing histidine or threonine residues). The BioConfirm software enabled simultaneous matching of multiple predicted impurity sequences and provided mirror-plot visualizations of charge distributions. Extracted ion chromatogram volumes allowed relative quantification of impurities as percentages of the intact peptide.

Benefits and Practical Applications

• Combines sequence confirmation and impurity profiling in a single assay to improve analytical throughput.
• High mass accuracy and resolution support confident detection of low-abundance synthesis by-products.
• Automated data processing with compliance controls (FDA 21 CFR Part 11, EU Annex 11) simplifies regulatory reporting.
• Adaptable to R&D and QA/QC workflows for a wide range of therapeutic peptides.

Future Trends and Opportunities

• Incorporation of ion mobility separation to resolve isomeric and post-translational variants.
• Application of machine learning for automated impurity pattern recognition and predictive modeling.
• Extension to advanced peptide modalities, including cyclic peptides and peptidomimetics.
• Development of higher-throughput platforms combining microflow LC and novel fragmentation strategies.

Conclusion

The combined use of AdvanceBio Peptide Plus chromatography, Agilent 6545XT LC/Q-TOF MS, and MassHunter BioConfirm software offers a robust, regulatory-compliant platform for comprehensive peptide sequence verification and impurity analysis, meeting the stringent demands of peptide therapeutic development.

References

1. Zhang B, Xu W, Yin C, Tang Y. Characterization of Low-Level D-Amino Acid Isomeric Impurities of Semaglutide Using Liquid Chromatography-High Resolution Tandem Mass Spectrometry. J Pharm Biomed Anal. 2023;224:115164.
2. U.S. Food and Drug Administration, Center for Drug Evaluation and Research. ANDAs for Certain Highly Purified Synthetic Peptide Drug Products That Refer to Listed Drugs for rDNA Origin: Guidance for Industry. 2021.
3. Mehta A, Marso SP, Neeland IJ. Liraglutide for Weight Management: A Critical Review of the Evidence. Obes Sci Pract. 2017;3(1):3–14.