Determination of Additives in Carbonated Beverages

Significance of the Topic

The accurate determination of preservatives and sweeteners in carbonated beverages is essential for regulatory compliance, quality control, and consumer safety. Key additives such as benzoate, sorbate, citrate, caffeine, and artificial sweeteners (aspartame, acesulfame, saccharin) must be quantified reliably to verify label claims, monitor manufacturing consistency, and detect undeclared ingredients.

Objectives and Study Overview

This study aimed to develop a single-run, high-throughput method for simultaneous separation and quantitation of seven common additives in carbonated drinks. By employing a novel mixed-mode weak anion-exchange/reversed-phase column, the work demonstrates baseline resolution of caffeine, aspartame, acesulfame, saccharin, sorbate, benzoate, and citrate in one injection. Method performance was evaluated in terms of precision, linearity, detection limits, and recovery in commercial samples.

Methodology and Instrumentation

The method uses an Acclaim Mixed-Mode WAX-1 column (5 µm, 4.6×150 mm) at 30 °C with an isocratic mobile phase of 120 mM KH2PO4 (pH 3.0) and acetonitrile (45:55, v/v). A 1.5 mL/min flow rate and UV detection at 210 nm enabled rapid analysis. Standard preparation involved individual stock solutions (500–1500 mg/L) combined into mixed stocks and serially diluted to generate calibration sets. Six commercial beverages (colas, diet colas, lemon-lime, orange soda) were filtered, diluted (3–10×), and injected directly.

Main Results and Discussion

• Precision: Retention time RSD ≤0.13% and peak area RSD ≤1.22% (seven injections).
• Linearity: Correlation coefficients ≥0.9988 over wide concentration ranges with method detection limits from 0.2 mg/L (aspartame) to 8.5 mg/L (citrate).
• Sample Analysis: Additive levels in all beverages were quantified, with spiked recoveries ranging from 86% to 113%. Diet colas lacked sugars, while a consistent unknown peak at ~1.6 min was identified as fructose in sugar-containing drinks.

The mixed-mode column’s dual retention mechanisms provided flexibility: hydrophobic interactions controlled nonpolar analyte retention, while ionic exchange tuned polar compound behavior. Mobile phase buffer strength and pH were adjusted to balance these interactions for optimal separation.

Benefits and Practical Applications

This protocol streamlines quality control by consolidating analysis of multiple additives into a single run, reducing solvent consumption, instrument time, and sample handling. It is directly applicable in beverage manufacturing, regulatory laboratories, and contract testing services for rapid screening and compliance testing.

Future Trends and Potential Applications

Advances in mixed-mode stationary phases and ultrahigh-pressure LC could further reduce analysis time and enhance resolution. Coupling to mass spectrometry may extend the method to novel sweeteners and emerging preservatives. Automated inline sample preparation and multivariate calibration could improve throughput and data reliability in high-volume quality control settings.

Conclusion

The presented mixed-mode LC-UV method achieves efficient, precise, and sensitive determination of seven key beverage additives in a single injection. Its robustness and simplicity make it a valuable tool for routine quality assurance and regulatory compliance in the soft drink industry.

References

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