Characterization of Poly(ethylene glycol) II

Importance of the Topic

Accurate characterization of poly(ethylene glycol) (PEG) molecular weight and distribution is critical in many fields including pharmaceuticals, biotechnology, and materials science. PEG is widely used for its solubility, low toxicity, and versatility in drug delivery and surface modification. High-resolution size exclusion chromatography (SEC) enables detailed analysis of PEG oligomers, ensuring consistent product performance and regulatory compliance.

Study Objectives and Overview

This application note demonstrates the use of PSS SUPREMA columns with small particle size to separate and characterize PEG samples over a wide range of molecular weights. Key goals include assessing column performance in aqueous SEC, establishing optimal sample preparation guidelines, and illustrating the resolution of narrow and broad polydispersity PEG standards.

Methodology

The SEC method was conducted under isocratic conditions in aqueous buffer. Major parameters:

• Mobile phase: Water with 0.05% sodium azide
• Flow rate: 1.00 mL/min
• Column temperature: 25 °C
• Calibration: ReadyCal-Kit for PEG standards
• Data processing: PSS WinGPC software
• Injection volume: 20 µL

Sample concentration recommendations depended on polydispersity index (PDI):

• Narrow PDI: 2 g/L for 100–10 000 Da; 1–2 g/L for 10 000–1 000 000 Da; 0.5 g/L or less for >1 000 000 Da
• Broad PDI (>1.5): 3–5 g/L for all molecular weight ranges

Used Instrumentation

Instrumentation and consumables:

• Columns: PSS SUPREMA sets for low (P/N 206-0001), medium (P/N 206-0002), high (P/N 206-0003), and ultrahigh (P/N 206-0004) molecular weights or equivalent single linear columns
• Detector: Shodex-RI71 refractive index detector
• Software: PSS WinGPC for chromatography control and data analysis

Main Results and Discussion

The small-particle PSS SUPREMA columns achieved clear separation of individual PEG oligomers. Narrow PDI samples produced sharp, baseline-resolved peaks, while broader distributions showed well-defined Gaussian profiles. The method demonstrated excellent reproducibility and sensitivity across the entire molecular weight range, confirming the benefit of smaller stationary-phase particles in aqueous SEC.

Benefits and Practical Applications

This SEC approach allows laboratories to:

• Obtain precise molar mass distributions for PEG-based products
• Perform reliable quality control during polymer synthesis and formulation
• Support regulatory submissions with detailed polymer characterization data

Future Trends and Applications

Emerging directions include coupling aqueous SEC with multi-angle light scattering or mass spectrometry detectors for absolute molecular weight determination, development of micro- and nano-scale SEC columns for high-throughput analysis, and advanced data algorithms for automated peak deconvolution and polymer architecture assessment.

Conclusion

PSS SUPREMA columns combined with refractive index detection provide a robust, high-resolution SEC method for PEG characterization. The workflow yields reproducible molecular weight profiles, supports a broad range of PDIs, and enhances confidence in polymer analysis for research and industrial laboratories.

References

No references were provided in the source document. The original application note will be republished by Agilent with updated branding.