Determination of Protein Molecular Weight and Size Using the Agilent 1260 Infinity Multi-Detector Bio-SEC Solution with Advanced Light Scattering Detection

Significance of the Topic

Size exclusion chromatography (SEC) with advanced light scattering detection provides direct, calibration‐free measurement of protein molecular weight (MW) and hydrodynamic radius (RH). This approach addresses limitations of conventional SEC where column interactions or conformational changes can lead to inaccurate results, making it critical for biotherapeutic development, quality control, and aggregation studies.

Study Objectives and Overview

This application note evaluates the Agilent 1260 Infinity Multi-Detector Bio-SEC Solution for simultaneous determination of protein MW and size across a broad range (11 kDa to 670 kDa). Key aims include assessing accuracy independent of sample load, comparing sensitivity of static light scattering versus UV detection for aggregates, and demonstrating UV quantification linearity.

Applied Methodology and Instrumentation

Protein standards (cytochrome c, lysozyme, ovalbumin, IgG, thyroglobulin) were separated on an Agilent Bio SEC-3 300 Å column under PBS (pH 7.4) at 0.75 mL/min and 30 °C. The system combined static light scattering (LS) at 90° for MW, dynamic light scattering (DLS) for RH measurement, and diode array detection (DAD) at 280 nm for concentration. Sample cooling (5 °C), metal-free flow path, and dual‐angle detection enhanced sensitivity and reproducibility.

Main Results and Discussion

• Accurate MW determination for all proteins with deviations within 3% of literature values, except thyroglobulin (702 vs 670 kDa) due to partial peak resolution challenges.
• Hydrodynamic radii matched published data (1.7–8.6 nm) with RSDs between 5–13% across injections.
• Static LS at 90° showed markedly higher sensitivity for aggregate detection compared to UV 280 nm.
• DAD quantification exhibited excellent linearity (R² > 0.999) over 39 µg/mL to 10 mg/mL.

Benefits and Practical Applications

The combined multi‐detector configuration delivers reliable MW and RH data independent of calibration standards and sample load. High aggregate sensitivity supports formulation screening, while quantitative UV detection aids in concentration determination. The metal‐free flow path reduces analyte adsorption, ensuring robust performance in biopharmaceutical research, quality assurance, and regulatory environments.

Future Trends and Potential Uses

Integration of multi‐detector SEC into high‐throughput automation platforms may accelerate biotherapeutic screening. Coupling with mass spectrometry and expanding to multi‐angle light scattering arrays will deepen structural characterization. Incorporation into process analytical technology (PAT) frameworks can enhance real‐time monitoring of protein production and stability.

Conclusion

The Agilent 1260 Infinity Multi-Detector Bio-SEC Solution provides a comprehensive SEC platform combining static and dynamic light scattering with UV detection for accurate, calibration-free measurement of protein MW and size. Its high sensitivity to aggregates and robust quantification capabilities make it a valuable tool for biotherapeutic development and quality control.

Reference

Agilent Technologies. Schneider S. Determination of Protein Molecular Weight and Size Using the Agilent 1260 Infinity Multi-Detector Bio-SEC Solution. Application Note, 2014.