Advanced Monoclonal Antibody Peptide Mapping Using Multi-Reflecting TOF MS Technology

Importance of the Topic

Peptide mapping of monoclonal antibodies (mAbs) plays a critical role in biotherapeutic development, enabling confirmation of protein identity, sequence integrity and localization of post-translational modifications (PTMs) or impurities. High-confidence, automated workflows support regulatory compliance, process monitoring and late-stage product commercialization by delivering detailed molecular insights.

Goals and Overview of the Study

This application note evaluates the performance of the ACQUITY™ Premier UPLC system coupled with the Xevo™ MRT multi-reflecting TOF mass spectrometer for mAb peptide mapping. The study uses the Waters™ NIST mAb tryptic digest standard and the waters_connect UNIFI™ App to demonstrate sensitivity, mass resolution, accuracy and dynamic range in routine peptide mapping workflows.

Methodology and Instrumentation Used

Sample preparation involved reconstitution and dilution of a lyophilized tryptic digest of NIST Reference Material 8671. Chromatography was performed on an ACQUITY Premier BEH C18 column (1.7 μm, 2.1×100 mm) with a water/ACN gradient containing 0.1% formic acid. The Xevo MRT MS system operated in MSE mode (data-independent acquisition) over m/z 50–2000 with sub-ppm mass accuracy, a 50 Hz scan rate, dual-gain ADC detector and multi-reflecting flight path for up to 100,000 resolution at 50 Hz.

Main Results and Discussion

• Sequence coverage of 96% for the light chain and 98% for the heavy chain with mass errors below 1 ppm.
• Detection of low-level PTMs, exemplified by oxidation of the DTLMISR peptide (+15.9949 Da) with distinct retention time shifts and high-quality fragment spectra.
• Dynamic quantitation range spanning five orders of magnitude (0.02 to 2000 ng) with linearity (R² = 0.999) and RSD <10%.
• Reproducibility demonstrated by ten replicate injections of the HC T25 glycopeptide (G0F) with intensity RSD of 1.5%.
• Automated glycosylation profiling across two mAb batches, enabling sample-to-sample comparison of Man5 levels.

Benefits and Practical Applications of the Method

• High sensitivity for in-depth characterization and low-level variant detection.
• Wide dynamic range to quantify product variants and impurities.
• Consistent sub-ppm mass accuracy and high resolution for confident peptide assignment.
• Integrated, compliance-ready workflow for streamlined data acquisition, processing and reporting.

Future Trends and Potential Applications

Advances in multi-reflecting TOF technology and data-independent acquisition are expected to drive deeper proteoform characterization, faster throughput and expanded use of peptide mapping in critical quality attribute (CQA) monitoring, biosimilar comparability studies and high-volume screening.

Conclusion

The combination of ACQUITY Premier UPLC and Xevo MRT MS delivers a robust, high-performance platform for mAb peptide mapping. Sub-ppm mass accuracy, high resolution and broad dynamic range, coupled with automated UNIFI App workflows, enable reliable sequence confirmation, PTM localization and quantitation of product variants to support biopharmaceutical development and commercialization.

References

1. EMA Guideline on development, production, characterisation and specification for monoclonal antibodies, EMA/CHMP/BWP/532517/2008, 2016.
2. Nilini Ranbaduge et al., Routine Peptide Mapping Analysis using the BioAccord System, Waters App Note 720006466, 2019.
3. Kellen DeLaney et al., Peptide Mapping and MAM Workflow for Biosimilar mAb Comparison on Xevo G3 QTof, Waters App Note 720007632, 2022.
4. Vera B. Ivleva et al., Automated LC-MS Peptide Mapping with UNIFI, Waters App Note 720004620, 2013.