Determination of brominated vegetable oils in soft drinks using combustion ion chromatography

Importance of the Topic

Determination of brominated vegetable oils in soft drinks is critical for ensuring beverage stability, accurate labeling, and regulatory compliance. BVO is used to emulsify citrus flavors but is restricted or banned in many regions due to health concerns. Reliable analytical methods are essential for quality control in beverage production and to address public scrutiny.

Objectives and Study Overview

This study aims to demonstrate a rapid and automated approach for quantifying total and free bromide from BVO in carbonated beverages using pyro-hydrolytic combustion ion chromatography. The method was evaluated for accuracy, precision, sensitivity, and applicability to commercial soft drinks and ginger beer samples.

Methodology and Instrumentation

Sample Preparation

• Fifty-microliter aliquots of degassed beverage were combusted.
• Degassing was achieved by ultrasonic agitation or vacuum filtration to remove oil suspensions.

Combustion and Absorption

• Pyro-hydrolytic combustion at 900 to 1000 °C in argon/oxygen overlap mode for 5 minutes.
• Bromine absorbed in 30 mg/L hydrogen peroxide solution.

Ion Chromatography

• Anion-exchange separation on a Dionex IonPac AS18-4µm column.
• Eluent generated electrolytically (23 mM KOH), flow rate of 1 mL/min at 30 °C.
• Detection by suppressed conductivity using a dynamic anion suppressor.

Instrumentation

• Mitsubishi AQF-2100H automatic combustion unit with boat controller, sample changer, furnace, and gas absorption unit.
• Thermo Scientific Dionex Integrion HPIC system with eluent generator, trap column, suppressor, and conductivity detector.

Key Results and Discussion

• Recoveries ranged from 90 to 102% with RSDs below 3%.
• Method detection limit was 0.34 mg/L bromide (3× S/N at 0.5 mg/L standard).
• Linearity was verified over 0.5 to 25 mg/L with r² = 0.998.
• Analysis time per sample was 13 minutes after initial equilibration.
• Application to five beverage samples yielded expected BVO levels in one cola, trace levels in another, and no detection in the remaining three samples.

Benefits and Practical Applications of the Method

This combustion IC approach offers:

• Automated matrix elimination for non-polar oil additives in ionic matrices.
• High throughput with fast cycle times.
• Sensitivity and precision suitable for regulatory and quality control laboratories.
• Capability to profile incoming BVO lots and monitor formulation consistency.

Future Trends and Potential Applications

• Extension to other halogenated food additives and environmental samples.
• Integration with mass spectrometric detection for structural confirmation.
• Miniaturized or portable CIC systems for field testing.
• Data analytics and digital workflows to enhance QA/QC processes.

Conclusion

Pyro-hydrolytic combustion ion chromatography provides a robust, reproducible, and automated solution for quantifying brominated vegetable oils in complex beverage matrices. The method meets requirements for sensitivity, accuracy, and throughput, supporting regulatory compliance and quality assurance in the beverage industry.

Reference

1. Bendig P, Maier L, Lehnert K, Knapp H, Vetter W. Mass spectra of methyl esters of brominated fatty acids and their presence in soft drinks and cocktail syrups. Rapid Commun Mass Spectrom. 2013;27:1083–1089.
2. Thermo Scientific Application Note AN72917 Fast determinations of brominated compounds in carbonated beverages using oxidative pyrolytic combustion and ion chromatography.
3. Thermo Fisher Scientific AppsLab Digital Library