Molecular Weight Confirmation of a Peptide Using MS Spectral Deconvolution for OpenLab CDS and the Agilent InfinityLab LC/MSD XT System

Significance of Topic

Intact mass confirmation of peptides and proteins by LC/MS is a key analytical approach in biopharmaceutical research and quality control. It enables rapid verification of molecular weight, detection of post-translational modifications, and assessment of sample integrity without extensive sample preparation or high-resolution instrumentation.

Objectives and Study Overview

This application demonstrates a workflow for confirming the molecular weight of a recombinant 42-amino acid peptide, gastric inhibitory peptide-1 (GIP-1), and identifying its oxidized variant. The study employs Agilent OpenLab CDS version 2.8 with the MS Spectral Deconvolution feature on an Agilent InfinityLab LC/MSD XT system to streamline analysis and reporting.

Methodology and Instrumentation

The peptide samples were separated on an Agilent 1290 Infinity II LC with a ZORBAX RRHT StableBond 2.1 x 50 mm column at 80 °C using a gradient of 0.1 percent formic acid in water and acetonitrile. The flow rate was 0.5 mL/min and UV detection recorded at 285 nm. Mass spectra were acquired with an Agilent InfinityLab LC/MSD XT equipped with an ESI source in positive polarity, drying gas at 350 °C, 10 L/min flow, 35 psi nebulizer, and capillary voltage of 4000 V. Scan range extended from m/z 400 to 2000 at 2.5 Hz.

Results and Discussion

Chromatograms of frozen GIP-1 aliquots revealed two peaks at retention times of 3.8 and 4.0 minutes. MS spectra displayed typical multi-charged envelopes. Deconvolution identified masses of 4982.7 Da and 4998.7 Da, corresponding to unmodified GIP-1 and an oxidized form with a 16 Da mass shift. Forced oxidation using hydrogen peroxide confirmed the identity of the oxidized species, and fresh standards ruled out storage artifacts. Automated PDF reporting summarized deconvoluted masses and relative abundances, enhancing confidence in component assignments.

Benefits and Practical Applications

• The automated deconvolution workflow on a unit mass instrument offers a cost-effective alternative to high-resolution MS for routine intact mass confirmation.
• Rapid identification of impurities and modifications supports quality control processes in peptide production.
• Integrated reporting within OpenLab CDS reduces manual data handling and accelerates time to result.

Future Trends and Opportunities

• Advancements in deconvolution algorithms may improve resolution of complex charge envelopes and minor variants.
• Integration with high-throughput screening and automated sample preparation will further increase laboratory productivity.
• Combining unit mass platforms with machine learning could enable predictive quality monitoring and real-time process control.

Conclusion

The combination of Agilent 1290 Infinity II LC, InfinityLab LC/MSD XT, and OpenLab CDS with MS Spectral Deconvolution delivers a robust, streamlined solution for peptide molecular weight confirmation. This approach balances cost, ease of use, and analytical confidence, making it ideal for both research and routine quality control settings.

Reference

1. Fast and Simple Protein Molecular Weight Confirmation Using the Agilent InfinityLab LC/MSD XT Mass Selective Detector. Agilent Technologies application note 5994-0188EN, 2019.
2. Critical Quality Attribute Monitoring of mAbs at the Intact and Subunit Levels Using a Cost-Effective, Simple and Robust LC/MS Solution. Agilent Technologies application note 5994-1349EN, 2019.
3. Unit Mass Spectral Deconvolution for Molecular Weight Confirmation of Large Molecules. Agilent Technologies technical note 5994-6928EN, 2023.