Fast determinations of brominated compounds in carbonated beverages using oxidative pyrolytic combustion and ion chromatography

Importance of the Topic

Brominated vegetable oil (BVO) is widely used as an emulsifier in citrus-flavored carbonated beverages to maintain flavor stability. Regulatory limits and consumer health concerns over BVO intake have led to bans in multiple regions and interim restrictions in the U.S. Accurate, rapid analysis of total brominated compounds is essential for quality control, label compliance, and safety monitoring.

Objectives and Overview of the Study

This application note presents a novel analytical approach combining oxidative pyrolytic combustion with high-pressure ion chromatography (CIC) for direct determination of brominated compounds in carbonated beverages. The study aims to develop a fast, automated method to quantify total bromide derived from BVO and distinguish it from free bromide in complex matrices.

Methodology and Instrumentation

• Sample Preparation: 50 µL aliquots of beverage are introduced via an automatic sampler into a quartz boat.
• Oxidative Pyrolytic Combustion: The sample is pyrolyzed at 900 °C under argon, then combusted at 1000 °C with oxygen and water vapor to convert organobromine to HBr gas.
• Collection: Evolved HBr is absorbed in a 30 mg/L hydrogen peroxide solution, yielding bromide in aqueous form; dilution factor ~425×.
• Ion Chromatography: Bromide is separated on a 4 × 150 mm IonPac AS18 column with a guard, using 23 mM KOH eluent generated in-line, and detected by suppressed conductivity.

Used Instrumentation

• Mitsubishi AQF-2100H pyrolysis/combustion system with ABC-210 controller, ASC-250L sampler, GA-210 absorption unit.
• Thermo Scientific Dionex Integrion HPIC system: RFIC pump, EGC500 KOH eluent generator, CR-ATC600 trap column, high-pressure degasser, ADRS600 suppressor, IonPac AG18 guard, AS18 analytical column, Chromeleon CDS.

Main Results and Discussion

• Bromate spiking tests confirmed that bromate is quantitatively converted to bromide during combustion with 94% recovery; no residual bromate detected.
• The method LOD for bromide is 0.34 mg/L; linear calibration from 0.5 to 25 mg/L (r² ≥ 0.998).
• A BVO reference standard contained 2.3 mg/L bromide by CIC, corresponding to ~2.3% bromine content, highlighting variability in commercial BVO formulations.
• Analysis of three carbonated beverages showed negligible free bromide (

Benefits and Practical Applications

The pyrolytic CIC approach fully eliminates matrix interferences, offers a rapid turnaround (13 min per sample), and integrates automated sampling and data handling. It is ideal for routine quality assurance of beverages and verification of BVO levels for regulatory compliance.

Future Trends and Applications

Potential extensions include analysis of other halogenated additives and contaminants in food, integration with mass spectrometric detection for structural elucidation, miniaturized high-throughput platforms, and broader deployment in environmental and industrial process monitoring.

Conclusion

Oxidative pyrolytic combustion combined with reagent-free ion chromatography provides a robust, sensitive, and high-throughput method for total brominated compound determination in carbonated beverages. The method simplifies sample preparation, ensures complete conversion to bromide, and meets accuracy and precision requirements for regulatory and quality control applications.

Reference

1. U.S. Food and Drug Administration. Code of Federal Regulations, Title 21, Part 101. Food Labeling, 2010.
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4. Thermo Scientific. Determination of Fluoride in Tea by Combustion IC, App Note AN72268, 2017.
5. Thermo Scientific. Determination of AOX in Wastewater by CIC, App Note AN72333, 2017.
6. Thermo Scientific. Determination of Halogens and Sulfur in Aromatics by CIC, App Note AN72693, 2018.
7. Thermo Fisher Scientific. Combustion IC System brochure, 2019.