Sugar screening using Eurokat columns

Importance of the Topic

In modern biorefineries, precise identification and quantification of C5 and C6 sugars and their alcohol derivatives are essential for optimizing bioethanol production, valorizing fermentation by-products, and ensuring process quality control.

Objectives and Study Overview

This study aimed to screen sixteen sugar and sugar alcohol standards across four ion-exchange Eurokat columns (Ca, Na, Pb, H) to determine which column chemistry provides the best separation performance for fermentation broth analysis.

Methodology and Used Instrumentation

An isocratic HPLC system equipped with a degasser, autosampler (AZURA AS 6.1L), column oven (AZURA CT 2.1), pump (AZURA P6.1L LPG), and refractive index detector (AZURA RID 2.1L) was employed. Columns packed with sulfonated styrene-divinylbenzene resin were modified with Ca²⁺, Na⁺, Pb²⁺ or H⁺ ions. Method parameters:

• Flow rate: 0.5 mL/min (Ca, Na, Pb), 0.7 mL/min (H)
• Column temperature: 75 °C (Ca, Na, Pb), 60 °C (H)
• Injection volume: 20 µL
• Eluent: Water (Ca, Na, Pb), 0.01 N H₂SO₄ (H)

Main Results and Discussion

The Ca and Pb columns delivered clear grouping of analytes: oligosaccharides eluted first (<13 min Ca, <18 min Pb), monosaccharides mid-range, and sugar alcohols last (>20 min Ca, >24 min Pb), with resolutions often exceeding 2. The Na column effectively separated oligosaccharides from other classes but struggled with mixed oligosaccharide pairs. The H column showed lower overall resolution and induced sucrose hydrolysis into glucose and fructose on-column. Comparative pairwise tests revealed:

• Ca column: excellent baseline separation of glucose/mannitol (Res≈10.6).
• Na column: superior separation of arabinose/fructose (Res≈1.94) compared to Ca.
• Pb column: improved arabinose/fructose separation over Ca (Res≈1.80).
• H column: baseline resolution of rhamnose/glucose (Res≈3.11), outperforming Ca.

Benefits and Practical Applications

These results guide the selection of Eurokat columns tailored to sample composition, enabling reliable analysis of fermentation products, impurity profiling in QA/QC laboratories, and support for biorefinery process optimization.

Future Trends and Possibilities

Potential developments include coupling multiple Eurokat chemistries in series for multidimensional separations, replacing Pb-modified phases with non-toxic alternatives, integrating mass spectrometric detection for enhanced sensitivity, and automating rapid screening workflows for complex biomass hydrolysates.

Conclusion

Eurokat Ca and Pb columns exhibit the broadest utility for separating a wide range of sugars and sugar alcohols from fermentation samples. Selection should consider target analyte classes and application constraints, with Na and H variants providing complementary strengths for specific compound pairs.

References

1. Aced G., Möckel H.J. Liquid Chromatography: Fundamentals of HPLC, VCH 1991.
2. EFSA CONTAM Panel. Scientific Opinion on Lead in Food, EFSA Journal 2010;8(4):1570.
3. KNAUER. Column Care and Regeneration – Eurokat, 2018.