Size Exclusion Chromatography of a Dextran Using Acclaim SEC-300 versus Acclaim SEC-1000

Significance of the Topic

The accurate analysis of cetylpyridinium chloride and polysaccharide excipients like dextran is essential for ensuring the safety and efficacy of oral care formulations.
Size-exclusion chromatography (SEC) provides a non-interactive separation based on molecular size, minimizing potential chemical alterations during analysis.
Reliable quantification of these components supports quality control in pharmaceutical and consumer health products.

Objectives and Study Overview

This application note demonstrates the use of two SEC columns for simultaneous analysis of a low-molecular-weight cationic surfactant and a high-molecular-weight polymer.
The main goals are to achieve clear peak resolution, minimize interference, and validate a robust method suitable for routine quality control.

Methodology and Instrumentation Used

Chromatographic system and columns

• Thermo Scientific Dionex ICS-3000 system equipped with conductivity detector and UV absorbance at 220 nm
• Two SEC columns tested:
  • Acclaim SEC-300 Surfactant Plus, 3 µm particle size, 4.6 × 300 mm
  • Acclaim SEC-1000, 3 µm particle size, 3.0 × 150 mm

Mobile phase and conditions

• Gradient of three components:
  • Acetonitrile
  • 100 mM formic acid
  • Water
• Flow rate: 0.5 mL/min
• Column temperature: 25 °C
• Injection volume: 5 µL
• Suppressor: Dionex CSRS 300 (2 mm), external water flow 1.0 mL/min, current 8 mA

Sample preparation

• Standard solution containing dextran (40 000 Da) at 5 mg/mL in mobile phase

Main Results and Discussion

Both columns provided sharp, symmetric peaks for cetylpyridinium and dextran.
Retention times:

1. Sodium ions eluted early, detected by conductivity
2. Cetylpyridinium peak observed at UV 220 nm

The surfactant plus stationary phase delivered reduced ionic interactions, enhancing peak shape.
Dextran elution profile confirmed size-based separation without nonspecific adsorption.
Conductivity suppression effectively removed background electrolyte signals, improving sensitivity.

Benefits and Practical Applications

Key advantages of the developed method include:

• Simultaneous detection of ionic surfactants and neutral polymers in complex formulations
• Minimal sample preparation with direct injection of formulation dilutions
• Robustness suitable for high-throughput quality control in pharmaceutical and personal care industries
• Dual detection modes ensure reliable quantification of multiple analyte classes

Future Trends and Potential Applications

Advances in SEC column chemistries may further improve resolution of closely sized analytes.
Integration with mass spectrometry could enable structural identification of polymer impurities.
Automation of sample handling and data processing will enhance throughput in manufacturing environments.
Application of similar methods to other charged excipients and active ingredients can broaden the role of SEC in formulation analysis.

Conclusion

The described size-exclusion chromatography method demonstrates effective separation and quantification of cetylpyridinium chloride and dextran in mouthwash formulations.
Use of surfactant-compatible SEC columns and conductivity suppression ensures high sensitivity and reproducibility, meeting stringent quality control demands.

Reference

Thermo Fisher Scientific Application Note PB20627_E and PB20748_E