Analysis of Polystyrene with Antioxidant Additive Using Prominence-i GPC System

Significance of the Topic

Gel permeation chromatography is essential for characterizing polymer molecular weight distributions and detecting trace additives that influence material performance and stability. Combining differential refractive index and photodiode array detection enables simultaneous quantitation of the main polymer and UV-absorbing minor components, improving analytical efficiency in polymer quality control and research.

Objectives and Overview

This study demonstrates the analysis of polystyrene containing a phenolic antioxidant, Irganox 1010, using the Shimadzu Prominence-i GPC system. The goals are to obtain molecular weight distribution of polystyrene, identify and quantify Irganox 1010, and validate calibration linearity for both polymer and additive.

Methodology and Instrumentation

Analyses were conducted on the Prominence-i integrated HPLC, equipped with a RID-20A differential refractive index detector and an internal PDA detector. The column oven accommodates up to three GPC columns. Analytical conditions included:

• Column Shodex KF-804L, 300 × 8 mm I.D.
• Mobile phase tetrahydrofuran (without stabilizer), 1.0 mL/min
• Column temperature 40 °C, injection volume 5 µL
• PDA detection at 230 nm, conventional flow cell
• RI detection via RID-20A, cell temperature 40 °C, response time 1 s

Main Results and Discussion

Chromatograms revealed the polystyrene peak at approximately 7.5 min, followed immediately by the Irganox 1010 peak. The antioxidant was scarcely visible by RI but was clearly detected by PDA when the detection wavelength was optimized. The PDA also provided the UV absorption spectrum of Irganox 1010 for qualitative confirmation.
A calibration curve for polystyrene spanned molecular weights from 3 950 to 197 000 with R2 = 0.9995, demonstrating excellent linearity. The molecular weight distribution of the sample yielded Mw = 26 078 and Mn = 15 422, giving a polydispersity index of 1.69.
The calibration of Irganox 1010 over 10–100 mg/L produced a linear response with R2 = 0.9998. Based on this curve, the antioxidant content in the sample was determined as 10.8 mg per gram of polystyrene.

Benefits and Practical Applications

The combined RI and PDA detection strategy allows:

• Simultaneous determination of polymer molecular weight distribution and trace-level additives
• High-sensitivity quantitation of UV-absorbing stabilizers
• Qualitative verification via UV spectral data

This approach enhances throughput in polymer QC laboratories and supports research on polymer stabilization.

Future Trends and Opportunities

Advancements may include coupling multiangle light scattering detectors for absolute molecular weight measurement, integrating automated column-switching for expanded separation ranges, and applying advanced chemometric methods to improve analysis of complex polymer–additive systems. Development of greener mobile phases and miniaturized GPC systems could further broaden applications in academic and industrial settings.

Conclusion

The Prominence-i GPC system effectively provides comprehensive analysis of polystyrene and its antioxidant additive. The method delivers reliable molecular weight distribution data, sensitive detection and quantitation of trace additives, and qualitative spectral confirmation, making it a valuable tool for polymer analysis.

References

No external literature references were provided in the source document.