Dual EGC – a simple solution for carbohydrate analysis

Significance of the topic

The analysis of complex carbohydrates is critical across biotechnology, food science, and pharmaceutical quality control. Precise separation and quantitation of oligosaccharides, inulins, and simple sugars inform product safety, nutritional profiling, and process monitoring. The Dual Eluent Generation Cartridge (Dual EGC) mode advances reagent-free ion chromatography by automating gradient eluent preparation, minimizing human error, and enhancing instrument uptime.

Objectives and study overview

This application note introduces Dual EGC mode for Thermo Scientific™ Dionex™ RFIC™ systems, demonstrating its performance in replacing manual NaOH/NaOAc gradients with electrolytically generated KOH/KMSA gradients. The goals include assessing reproducibility, maintenance reduction, and method flexibility on analytical (1.0 mm) and capillary (0.4 mm) column formats using common carbohydrate standards and real samples.

Methodology and instrumentation

Reagent-free eluent gradients are generated by placing a methanesulfonic acid (MSA) cartridge upstream of a potassium hydroxide (KOH) cartridge. By adjusting current, the system produces basic KMSA/KOH eluents up to 200 mM total concentration. Dual EGC mode operates on the Dionex ICS-6000 HPIC and capillary systems with flow ranges of 20–200 µL/min (1 mm) and 1–20 µL/min (0.4 mm). Key components include:

• Dionex EGC 400 MSA and EGC 400 KOH cartridges (analytical)
• Dionex EGC MSA (Capillary) and EGC KOH (Capillary) cartridges
• Dionex CarboPac PA200 and PA1 columns in 3, 1.0, and 0.4 mm formats
• Non-metallic HPLC pump, RFIC+ eluent degasser, and integrated amperometric detector
• Chromeleon CDS for gradient control and data management

Main results and discussion

Comparative studies using fetuin oligosaccharides and inulin demonstrated that Dual EGC gradients yield equivalent separation quality to manual eluents while offering improved baseline stability. Transitioning from 3 mm to 1 mm and 0.4 mm columns reduced analysis time and solvent consumption without compromising resolution. Fruit juice analyses (apple, cranberry, orange) confirmed accurate quantitation of sorbitol, glucose, fructose, and sucrose in diluted samples.

Benefits and practical applications

Dual EGC mode provides:

• Automated, high-purity gradient generation eliminating CO2 intrusion and sodium acetate variability
• Consistent retention times and baseline stability for reliable carbohydrate profiling
• Minimal maintenance by limiting exposure of pump components to harsh reagents
• Flexible gradient programming within existing RFIC systems without additional pumps

Future trends and opportunities

Advancements may include expanded cartridge chemistries for broader analyte classes, integration with ultrahigh-pressure and multidimensional chromatography, and coupling with mass spectrometry. Continuous refinement in cartridge design could enable even higher concentration ranges and faster gradient switching, supporting next-generation glycomics workflows.

Conclusion

Dual EGC mode streamlines complex carbohydrate analysis by replacing manual eluent preparation with automated, reagent-free generation of KOH/KMSA gradients. This approach enhances reproducibility, reduces maintenance, and delivers flexibility for gradient-based methods on both analytical and capillary scales.

Reference

(No formal literature citations were provided in the source text.)