Chromatographic separation of Oligosaccharides and Monosaccharides

Importance of the Topic

Analytical separation of mono- and oligosaccharides is critical in food, pharmaceutical and biotechnology industries for quality control, nutritional profiling and process monitoring. Effective chromatographic methods enable accurate quantification of sugars, assessment of sample purity and reliable detection of carbohydrate-related compounds in complex matrices.

Objectives and Study Overview

This application note evaluates the performance of a Shim-pack SUR-Na column operated in size-exclusion and sodium-based ligand exchange mode for the separation of 21 common sugars and sugar alcohols. The goals were to demonstrate chromatographic resolution, establish retention indices and illustrate suitability for routine sugar analysis.

Methodology

The method employs isocratic elution with water at elevated temperature to exploit both size-exclusion and ion-exchange interactions between saccharides and sodium ions immobilized on the stationary phase.

Used Instrumentation

• Liquid chromatograph: Nexera lite
• Analytical column: Shim-pack SUR-Na, 250 mm × 7.8 mm I.D., 8 μm (2 columns in series)
• Guard column: Shim-pack SUR-Na (G), 50 mm × 7.8 mm I.D., 8 μm
• Mobile phase: ultrapure water
• Flow rate: 0.5 mL/min
• Column temperature: 60 °C
• Injection volume: 10 µL
• Detector: refractive index detector (RID)

Main Results and Discussion

The method achieved baseline separation of mono- and small oligosaccharides between 0 and 36 minutes. Retention times increase systematically with degree of polymerization, with maltoheptaose eluting last. Low-molecular-weight sugar alcohols and monosaccharides such as ethanol, glycerol and fucose elute early due to minimal exclusion. A retention index constructed from these data shows a near-linear relationship with saccharide size, indicating robust size-exclusion behavior modified by sodium ligand exchange. The dual retention mechanism provides improved selectivity compared to pure size-exclusion mode.

Benefits and Practical Applications

• Simple isocratic water elution reduces solvent costs and system maintenance.
• High reproducibility and resolution support routine QC in food, beverage and pharmaceutical industries.
• Compatibility with RID makes the method accessible to laboratories without MS detection.
• Retention index data facilitate rapid identification of unknown sugars in complex samples.

Future Trends and Opportunities

Advances may include coupling this separation mode with mass spectrometry for enhanced structural characterization of oligosaccharides, adoption of shorter UHPLC columns to reduce analysis time, development of mixed-mode stationary phases for greater isomer discrimination and integration of chemometric tools for automated sugar profiling.

Conclusion

The Shim-pack SUR-Na column in sodium-based ligand exchange and size-exclusion mode provides an efficient, robust and cost-effective platform for separating and profiling mono- and oligosaccharides. The established retention indices and straightforward mobile phase requirements make it well suited for diverse analytical applications in research and industry.