Efficient and sensitive peptide mapping approach by μPAC columns with ultralow sample loading

Importance of the Topic

Peptide mapping is a cornerstone in biopharmaceutical analysis, providing detailed insights into antibody primary sequences, post-translational modifications and mutations. High sensitivity and reproducibility at ultralow sample loads are essential for efficient quality control and characterization of monoclonal antibodies.

Study Objectives and Overview

This work aimed to demonstrate the reproducibility and sensitivity of peptide mapping workflows using Thermo Scientific µPAC Neo HPLC columns. The study evaluated sequence coverage for heavy and light chains of a NISTmAb tryptic digest under ultralow loadings and assessed the columns’ ability to resolve oxidation, deamidation and glycopeptides.

Methodology and Instrumentation

Sample Preparation:

• NISTmAb tryptic digestion standard reconstituted in 0.1% formic acid or 0.1% TFA at concentrations down to 1.6 ng.
• Direct injection and trap-and-elute workflows to compare recovery of hydrophilic peptides.

Chromatography:

• 50 cm µPAC Neo column with 15- and 30-minute gradients at 0.2–0.5 µL/min.
• 5.5 cm µPAC Neo High Throughput column with 5- and 10-minute gradients at 1–1.5 µL/min.

Mass Spectrometry:

• Orbitrap Exploris 480 operated in positive-ion data-dependent acquisition (Top8).
• MS1 resolution 30 K, MS2 resolution 7.5–15 K, isolation window 2 m/z, HCD collision energy 30.

Data Analysis:

• Thermo Scientific BioPharma Finder 5.1 with ≤10 ppm precursor tolerance, MS area ≥1E5, and ≤2 missed cleavages.

Instrumentation Used

• Thermo Scientific Vanquish Neo UHPLC system
• Thermo Scientific Orbitrap Exploris 480 mass spectrometer
• µPAC Neo HPLC columns (50 cm and 5.5 cm High Throughput)
• Thermo Scientific PepMap Neo trap cartridges and nano/capillary emitters

Key Results and Discussion

Sequence coverage plateaued above 12 ng loading, with 20 ng delivering 96.4% heavy-chain and 98.6% light-chain coverage on both column formats. Total ion chromatograms confirmed optimal loading. µPAC columns separated oxidized vs. unmodified and deamidated vs. native peptides, enhancing PTM confidence. Glycoform separation was superior on the longer column. Incorporation of 0.1% TFA in a trap-and-elute workflow improved retention and resolution of small hydrophilic peptides missed in direct injection.

Benefits and Practical Applications

• High sensitivity mapping with minimal sample consumption for scarce or precious samples.
• Rapid turnaround (5–15 min runs) ideal for high-throughput QC screening.
• Enhanced resolution of PTMs such as oxidation, deamidation and glycosylation supports comprehensive antibody characterization.

Future Trends and Opportunities

Integration with data-independent acquisition could further boost coverage and quantitation. Advances in automated trap-and-elute modules and alternative ion-pairing agents may optimize analysis of highly hydrophilic peptides. Expansion of µPAC pillar chemistries may extend applications to broader proteomic and metabolomic workflows.

Conclusion

Thermo Scientific µPAC Neo columns enable efficient, sensitive and reproducible peptide mapping at ultralow sample loads. Both 50 cm and 5.5 cm formats achieve high sequence coverage with short gradients, improving PTM resolution and supporting high-throughput biopharmaceutical QC workflows.