SEC Analysis of Sodium Polyacrylate

Importance of the Topic

Sodium polyacrylate is a high-capacity superabsorbent polymer widely used in personal hygiene products and agriculture due to its ability to retain large volumes of water relative to its own weight.

Objectives and Study Overview

This study aims to evaluate the molecular weight characteristics of sodium polyacrylate using size-exclusion chromatography (SEC) with Agilent PL aquagel-OH columns. The focus is on determining weight-average molecular weight, polydispersity, and distribution profile.

Methodology and Instrumentation

The analysis was performed on an Agilent 1260 Infinity GPC/SEC system.

• Columns: Two PL aquagel-OH 40, 8 μm, 300 × 7.5 mm
• Eluent: 0.2 M NaNO3 with 0.01 M NaH2PO4 at pH 7
• Flow Rate: 1.0 mL/min
• Detection: Refractive Index detector

Main Results and Discussion

The chromatogram reveals a polymer sample with a weight-average molecular weight of approximately 13,000 Da. The aqueous eluent effectively minimizes ionic interactions, ensuring reliable peak resolution. The high efficiency of PL aquagel-OH columns, with over 35,000 theoretical plates per meter, contributes to sharp, well-defined elution profiles. The analysis provides insights into polydispersity and the overall shape of the molecular weight distribution.

Benefits and Practical Applications

• Aqueous SEC offers detailed molecular weight and distribution data critical for quality control of superabsorbent polymers.
• High column stability ensures consistent performance and extended lifetime, reducing downtime and operational costs.
• Results support formulation development in personal care and agricultural products by correlating polymer architecture with performance characteristics.

Future Trends and Potential Applications

• Integration of multi-angle light scattering or viscometry detectors to refine absolute molecular weight measurement and conformation analysis.
• Development of novel SEC stationary phases for improved separation of ultra-high molecular weight polymers.
• Automation and high-throughput platforms to support large-scale polymer screening in industrial settings.

Conclusion

SEC using Agilent PL aquagel-OH columns provides a robust approach for characterizing sodium polyacrylate. The method delivers essential data on molecular weight and distribution with high repeatability and operational stability, supporting both research and quality control in applications where superabsorbent performance is critical.