Advanced Polymer Chromatography Reverse Phase Method for Polymer Additives Using Tetrahydrofuran and Evaporative Light Scattering Detection in Under Three Minutes per Sample

Importance of the Topic

Polymers are subject to thermal, mechanical and photochemical degradation during processing and use. Additives such as UV stabilizers and antioxidants are essential to enhance polymer performance and longevity. Rapid and robust chromatographic methods that accommodate aggressive solvents like tetrahydrofuran (THF) enable high-throughput quality control and research in polymer formulation.

Objectives and Study Overview

This application note describes the conversion of a legacy high-performance liquid chromatography (HPLC) method into ultra-high performance (UHPLC) and ultra-performance liquid chromatography (UPLC) workflows for the separation of six polymer additives in under three minutes. The target analytes include two pairs of coeluting stabilizers (Tinuvin 327/328 and Irganox 1010/1076). An evaporative light scattering detector (ELSD) ensures compatibility with THF and detection of non-UV-active compounds.

Methodology and Instrumentation

Sample preparation involved dissolving each additive at 1.0 mg/mL in THF, diluting to 0.5 mg/mL, and injecting into LC vials. Three experiments used columns of decreasing particle size (5 µm, 2.5 µm, 1.7 µm) with gradient conditions scaled via a column calculator tool. Key operational parameters:

• Mobile phases: unstabilized THF and deionized water
• Temperatures: column 25 °C, sample 20 °C
• Flow rates scaled: 0.68, 0.58, 0.42 mL/min
• Injection volumes: 14, 3, 1 µL
• ELSD settings: drift tube 60 °C, gain 500, gas flow 60 psi

Used Instrumentation

• ACQUITY Advanced Polymer Chromatography (APC) System with polymer Quaternary Solvent Manager
• ACQUITY BEH C18 columns (5 µm, 2.5 µm, 1.7 µm)
• ACQUITY UPLC Evaporative Light Scattering Detector
• Empower Chromatography Data System 3

Main Results and Discussion

Experiment 1 (5 µm column) achieved baseline resolution of coeluting pairs within 12 minutes. Experiment 2 (2.5 µm) reduced run time to under 6 minutes while preserving resolution. Experiment 3 (1.7 µm) delivered separation in under 3 minutes, with resolution values above acceptance criteria for both Tinuvin and Irganox pairs. The method conversion preserved chromatographic quality and increased throughput fivefold.

Benefits and Practical Applications

• Time-saving: under three-minute analysis enables rapid screening
• Solvent compatibility: robust handling of THF without column swelling
• Flexibility: scalable method development via column calculator tool
• Detection sensitivity: ELSD identifies non-UV-active additives

Future Trends and Applications

Advances in sub-2 µm particle column technology and solvent-resistant system components will further decrease analysis times and improve sensitivity. Integration with automated sample preparation and real-time data processing could support in-line process monitoring and high-throughput polymer formulation screening. Emerging detectors such as charged aerosol detection may complement ELSD for enhanced dynamic range.

Conclusion

The study successfully translated an HPLC protocol for six polymer additives into a three-minute UPLC method using THF mobile phase and ELSD. The combination of ACQUITY APC System, BEH C18 columns, and Empower CDS demonstrates a robust workflow for rapid, high-resolution polymer additive analysis.

References

1. Jones M., Gough J., Twohig M. Comparison of HPLC and UHPLC Analysis of Polymer Additives, Waters Posters, 2017.
2. Lohmann C., Morrison D., Gough J. Polymer Additive Analysis Using THF and Advanced Polymer Chromatography, Waters Application Note 720006707EN, 2019.
3. Waters ACQUITY UPLC ELSD Specifications.
4. UPLC ELSD Getting Started Guide, Waters Corporation.
5. Tolinski M. Additives for Polyolefins, 2nd ed., William Andrew, 2015.
6. Bolgar M. et al. Handbook for the Chemical Analysis of Plastic and Polymer Additives, CRC Press, 2016.
7. Waters Beginners Guide to UPLC.
8. Waters ACQUITY APC p-QSM System Spec Sheet 720006702EN.
9. Waters BEH Technology Overview.
10. Waters Column Calculator Tool.
11. Chromatography Fundamentals: Resolution Significance.