Fast Separations of Anions and Organic Acids in a Carbonated Beverage Using High-Pressure Capillary IC

Importance of the Topic

Organic acids and common inorganic anions in carbonated beverages play crucial roles in maintaining freshness, controlling microbial growth, and delivering characteristic flavor profiles. Precise and rapid quantification of these species is essential to ensure product quality, comply with labeling regulations, and optimize manufacturing processes.

Objectives and Study Overview

This study aims to demonstrate high-pressure capillary ion chromatography (HPIC) for expedited separation of chloride, nitrate, sulfate, phosphate, and citrate in a carbonated diet cola. By increasing flow rates on a Thermo Scientific Dionex ICS-5000+ HPIC system equipped with an IonSwift MAX-200 column, the work explores reductions in analysis time while maintaining resolution and sensitivity.

Methodology

A degassed diet cola sample was diluted 1:10 with 18 MΩ·cm deionized water and filtered through a 0.45 µm syringe filter to remove carbonate and particulates. A potassium hydroxide gradient (2→50 mM over 15 min) was generated electrolytically using a Dionex EGC-KOH capillary cartridge. A 0.4 µL injection was performed at 30 °C on a 0.25 × 250 mm IonSwift MAX-200 column, with suppressed conductivity detection (ACES 300 suppressor, CRD 200 carbon removal device).

Used Instrumentation

• Thermo Scientific Dionex ICS-5000+ HPIC system (SP/DP pump, EG eluent generator, DC detector with IC Cube and high-pressure degas cartridge)
• Dionex AS-AP autosampler and Chromeleon CDS software
• IonSwift MAX-200 capillary column with CR-ATC trap, EGC-KOH cartridge, CRD 200 carbon removal device, and ACES 300 suppressor

Main Results and Discussion

Baseline separation of all five analytes was achieved in as little as 8 min at 25 µL/min—representing a 60% reduction in run time compared to 20 min at 10 µL/min. System backpressure increased from 1,900 psi at 10 µL/min to 4,500 psi at 25 µL/min, showcasing the HPIC system’s ability to operate up to 5,000 psi. Calibration curves for each analyte were linear (r² > 0.999) over a broad concentration range, and a 0.4 µL injection yielded sensitivity comparable to 40 µL on standard-bore columns.

Benefits and Practical Applications

• Significantly higher sample throughput with minimal increase in resource consumption
• Reduced water and waste generation (30–40 mL/day) and extended cartridge lifetime
• Lower sample injection volumes and always-ready operation for routine QA/QC in beverage production
• Compliance with regulatory labeling requirements for organic acid content

Future Trends and Opportunities

Advancements may include further miniaturization and integration of online degassing, coupling capillary HPIC with mass spectrometry for enhanced identification, and automated sample prep workflows. Emerging monolithic column chemistries and higher-pressure materials will drive even faster separations and broaden application scopes in food, beverage, and environmental analysis.

Conclusion

The Thermo Scientific Dionex ICS-5000+ HPIC platform paired with an IonSwift MAX-200 column enables rapid, efficient separations of key anions and organic acids in carbonated beverages. By leveraging elevated flow rates and high system pressures, laboratories can achieve substantial improvements in throughput, resource efficiency, and analytical performance.

Reference

1. Food Labeling. Code of Federal Regulations, Part 101, Title 21, 2010.
2. Thermo Fisher Scientific. Technical Note 113: Practical Guidance for Capillary IC, 2012.
3. Thermo Fisher Scientific. Dionex ICS-5000+ Installation Manual, Doc No. 065343, 2011.
4. Thermo Fisher Scientific. Product Manual for CES 300 Suppressors, Doc No. 065386, 2010.
5. Thermo Fisher Scientific. Technical Note 131: Configuring High-Pressure Capillary IC, 2012.
6. Thermo Fisher Scientific. AS-AP Operator’s Manual, Doc No. 065361, 2012.
7. Thermo Fisher Scientific. Application Brief 137: Inorganic Anions and Organic Acids in Juice, 2011.
8. Thermo Fisher Scientific. Application Note 169: Anion Determinations in Coconut Water, 2011.
9. Thermo Fisher Scientific. Application Note 169: Rapid Phosphate and Citrate in Soft Drinks, 2005.
10. Thermo Fisher Scientific. Application Update 142: Fast Phosphate and Citrate in Beverages, 2006.