Reproducibility and Reliability of GPC Analysis of Polystyrene on the Arc™ HPLC System

Significance of the Topic

Gel Permeation Chromatography (GPC) is essential for determining polymer molecular weight distributions, a critical parameter in materials science and quality control. Reliable and reproducible retention times ensure accurate calculation of molecular weight averages (Mn, Mw, Mp) and polydispersity. A system capable of withstanding strong organic solvents like THF without performance degradation is vital for routine polymer analysis in research and industrial laboratories.

Study Objectives and Overview

This study assessed the reproducibility, reliability and durability of the Waters Arc HPLC System equipped with a strong solvent compatibility kit for GPC analysis of polystyrene. Over five consecutive days, narrow polystyrene standards and a broad polystyrene sample were analyzed daily with replicate injections. Key goals included verifying retention time precision, calibration curve stability and consistency of calculated molecular weight values.

Methodology and Instrumentation

All analyses were performed under isocratic conditions using stabilized tetrahydrofuran as mobile phase at 1.0 mL/min and 40 °C column temperature. A four-column GPC bank (Styragel HR 3, HR 4, HR 4E and HR 5E) covered a wide MW range (approximately 50 Da to 4 M Da). Detection was by refractive index (10 pts/s, 40 °C). Samples and ReadyCal polystyrene standards (Mp ranges 370–2 520 000 Da) were dissolved in THF and injected at 50 µL. Data acquisition and processing used Empower™ 3.8.0 CDS with the GPC option.

Results and Discussion

Calibration curves generated each day showed a third-order fit between log molecular weight and retention time with R² consistently ≥ 0.9997. Intra-day retention time precision for key standards (Mp ≈ 277 000 Da and 133 000 Da) exhibited RSDs below 0.32%. Inter-day variability remained within 0.01 min. The broad polystyrene sample displayed Mn, Mw and Mp values within 10% of expected values and polydispersity within 5%, with retention time RSDs < 0.02% across five days. Overlay of molecular weight distribution plots confirmed day-to-day consistency.

Benefits and Practical Applications

• The Arc HPLC System with strong solvent compatibility kit delivers robust performance in THF for extended GPC use.
• High flow-rate precision ensures stable retention times and reproducible calibration curves.
• Integration with Empower CDS GPC option streamlines molecular weight calculations and reporting.
• Suitable for routine polymer quality control, materials research and industrial analytics.

Future Trends and Opportunities

Advances may include coupling GPC with multi-angle light scattering or mass spectrometry for absolute molecular weight determination. Miniaturized and high-throughput GPC formats, automated sample handling and AI-driven data interpretation promise faster, more comprehensive polymer characterization. Developing solvent-resistant materials and modules will further extend system lifetime and application scope.

Conclusion

The Arc HPLC System fitted with a strong solvent compatibility kit demonstrated excellent reproducibility and reliability in polystyrene GPC analysis over five days. It maintained stable retention times, consistent calibration performance and accurate molecular weight determinations, confirming its suitability for routine GPC workflows.

References

1. Empower GPC Software Getting Started Guide, Waters Corporation User Guide, 71500031303