Analysis of dextran using an AZURA® SEC System

Significance of the Topic

Dextran is a high-molecular-weight polysaccharide widely applied in food, pharmaceutical and cosmetic industries. Its functional properties, including viscosity, solubility and drug-carrier capacity, depend critically on molecular weight distribution. Accurate characterization of dextran’s molecular profile is therefore essential for quality control and research developments in various sectors.

Objectives and Study Overview

This study demonstrates the determination of dextran molecular weight distribution using the KNAUER AZURA® SEC system. By coupling AppliChrom® SuperOH-P 300 and 350 columns in series, the method aims to cover a broad range from 1 000 to 1 000 000 Da while maintaining high resolution and reliable identification of dextran in unknown matrices.

Methodology and Instrumentation

An isocratic SEC method with water/PBS buffer (pH 7.1) at a flow rate of 1 ml/min and 25 °C was established. Key parameters:

• Injection volume: up to 50 µl
• Detection: Refractive index detector (RID) at 10 Hz data rate, 0.1 s time constant
• Run time: 30 min

Critical instrumentation elements:

• Pump: AZURA® P 6.1L LPG with 10 ml stainless steel pump head
• Autosampler: AZURA® AS 6.1L (analytical HPLC)
• Detector: AZURA® RID 2.1L (refractive index)
• Thermostat: AZURA® CT 2.1
• Eluent tray: AZURA® E 2.1L
• Columns: AppliChrom® SuperOH-P 300 (7 µm, 300 × 8 mm, 1 000–300 000 Da) and SuperOH-P 350 (10 µm, 300 × 8 mm, 2 500–1 000 000 Da) in series
• Software: ClarityChrom® 9.1.0 with SEC/GPC extension

Main Results and Discussion

The SEC analysis of dextran produced a clear peak at 10.47 min, confirming the method’s ability to identify and resolve dextran across the targeted molecular weight range. The series connection of SuperOH-P 300 and 350 columns provided high plate counts and excellent resolution, enabling precise molecular weight profiling in a single 30 min run. This performance supports reliable characterization in complex or unknown sample matrices.

Benefits and Practical Applications

• Comprehensive molecular weight coverage from 1 000 to 1 000 000 Da
• High resolution and reproducibility for routine quality control
• Applicability to food, pharmaceutical and cosmetic product development
• Simple isocratic conditions with minimal method development

Future Trends and Opportunities

Advancements in SEC are anticipated to focus on multi-detector configurations, reduced solvent consumption and higher throughput formats. Emerging developments include micro-SEC systems for nanoscale analysis, integration with mass spectrometry for detailed structural insights and automated workflows for real-time quality assurance.

Conclusion

The KNAUER AZURA® SEC system, combined with AppliChrom® SuperOH-P columns, offers a robust, high-resolution platform for dextran molecular weight analysis. Its broad coverage and reliable performance make it an effective tool for research and industrial quality control.

References

1. Díaz-Montes, E. (2021). Dextran: Sources, Structures, and Properties. Polysaccharides, 2(3), 554–565.
2. Aman, A., Siddiqui, N. N., & Qader, S. A. U. (2011). Characterization and potential applications of high molecular weight dextran produced by Leuconostoc mesenteroides AA1. Carbohydrate Polymers, 87(1), 910–915.
3. Kim, C. J., Hamielec, A. E., & Benedek, A. (1982). Characterization of Dextrans by Size Exclusion Chromatography Using DRI/LALLSP Detector System. Journal Of Liquid Chromatography, 5(3), 425–441.
4. Huang, G., & Huang, H. (2018). Application of Dextran As Nanoscale Drug Carriers. Nanomedicine, 13(24), 3149–3158.
5. De Belder, A. N. (1993). Dextran. In Elsevier eBooks (pp. 399–425).