Elevate Your mAb Aggregate Analysis - High-resolution SEC with the Agilent 1290 Infinity II Bio LC System

Importance of the Topic

Monoclonal antibodies (mAbs) are central to modern biopharmaceuticals but present significant heterogeneity challenges. Aggregation can impact therapeutic efficacy and safety, making precise aggregate analysis a critical quality attribute in drug development and manufacturing. High-resolution size exclusion chromatography (SEC) is the preferred technique to monitor protein purity and determine molecular weight distributions, enabling robust quality control.

Objectives and Study Overview

This application note evaluates the performance of the Agilent 1290 Infinity II Bio LC System coupled with an AdvanceBio SEC column and ultralow dispersion capillaries in resolving protein aggregates. Key aims include comparing capillaries of various inner diameters, separating a five-protein standard and two mAbs, and integrating molecular weight determination in a single workflow using Agilent OpenLab GPC/SEC software.

Methodology and Instrumentation Used

Samples and Conditions:

• Protein mix for calibration: thyroglobulin, γ-globulin, ovalbumin, myoglobin, angiotensin II.
• Therapeutic mAbs: trastuzumab (Herceptin) and NISTmAb (IgG1κ).
• Stress protocol for NISTmAb: pH cycling between 6.0, 1.0, 10.0, and back to 6.0, followed by incubation at 60 °C for 60 minutes.

Instrument Configuration:

• Agilent 1290 Infinity II Bio High-Speed Pump and Ultra Low Dispersion kit (capillaries 0.07, 0.12, 0.17 mm).
• Agilent 1290 Infinity II Bio Multisampler with sample thermostat (4 °C).
• Agilent 1290 Infinity II Multicolumn Thermostat at 30 °C.
• Agilent 1290 Infinity II Variable Wavelength Detector, micro flow cell, 280 nm.
• AdvanceBio SEC column, 200 Å, 4.6 × 300 mm, 1.9 µm.
• Mobile phase: PBS pH 7.4, 0.35 mL/min, isocratic.
• Software: Agilent OpenLab 2.5 and GPC/SEC add-on 1.2.

Main Results and Discussion

Five-protein standard separation using 0.07 mm capillaries achieved baseline separation of early eluting dimers. A fourth-order polynomial calibration curve allowed precise molecular weight assignments. Trastuzumab monomer and dimer eluted at 6.489 min and 5.673 min with assigned masses of ~141 566 Da and ~321 609 Da.

Comparison of capillary diameters revealed that 0.07 mm tubing provided the sharpest peaks and highest resolution (USP 0.94 for key peaks), while larger diameters progressively degraded performance and increased peak width.

Analysis of native NISTmAb achieved resolution of 3.11 between monomer and dimer, with retention time and area RSDs below 0.3 % across all capillary sets. Under stress conditions, higher order aggregates and trimers were resolved (resolution 3.33), demonstrating the method’s sensitivity for complex mixtures.

Benefits and Practical Applications of the Method

• Enhanced detection of low-level aggregates and higher molecular weight species for robust quality control.
• Reduced maintenance costs due to biocompatible UHPLC design tolerating high-salt buffers.
• Integration of separation and molecular weight determination in one software platform streamlines workflows.

Future Trends and Opportunities

• Development of even lower-dispersion fluidic paths and next-generation sub-2 µm columns.
• Coupling high-resolution SEC with mass spectrometry for advanced structural characterization.
• Automation of stress studies and real-time data analytics using machine learning.
• Expansion toward microflow and nanoparticle aggregate analysis in biosimilar and novel biologic development.

Conclusion

The Agilent 1290 Infinity II Bio LC System with AdvanceBio SEC and ultralow dispersion capillaries delivers superior aggregate separation and accurate molecular weight determination in a single step. Its biocompatible design and low dead volume provide high resolution, reproducibility, and reduced operating costs, positioning it as a valuable tool for biopharmaceutical QC and research.

Reference

• Quantitation of mAb and ADC Aggregation Using SEC and an Aqueous Mobile Phase. Agilent Technologies application note, publication number 5991-6303EN, 2016.