Fast, Accurate and Flexible LC-PDA Method for the Determination of Citric Acid In Beverages

Importance of the Topic

Citric acid is a common additive in beverages, valued for its flavor‐enhancing and antioxidant properties. Accurate quantification of citric acid is essential for quality control, ensuring consistency in product taste and meeting regulatory specifications. Conventional analysis techniques can be time-consuming, require specialized instrumentation, or suffer from poor chromatographic performance due to the analyte’s high polarity and interaction with metal surfaces.

Objectives and Overview of the Study

This work presents a rapid, sensitive, and flexible UPLC-PDA method for quantifying citric acid in energy and sports drinks. The study evaluates chromatographic performance, method linearity, precision, and applicability to real beverage samples, leveraging an advanced low-adsorption UPLC system.

Methodology and Instrumentation

A gradient separation was performed on an ACQUITY Premier CSH Phenyl-Hexyl Column using 10 mM sodium phosphate buffer in water (A) and acetonitrile (B). Detection was carried out at 210 nm on an ACQUITY UPLC PDA Detector (190–500 nm spectral range). System and data handling utilized the ACQUITY UPLC H-Class System coupled with Empower 3 Software. Sample preparation involved tenfold dilution of beverages in HPLC-grade water, followed by 0.2 µm PVDF syringe filtration.

Main Results and Discussion

The method demonstrated excellent calibration linearity (12.5–600 ppm, R²>0.999, 1/X weighting, residuals <5%). Peak shape was improved by minimizing metal-analyte interactions using the Premier low-adsorption hardware, yielding tailing factors <2.2. Retention time for citric acid was approximately 1.8 minutes. Seven replicate injections of sports and energy drink samples showed %RSD <0.6% for retention time and peak area. Quantified concentrations were 1706 ppm in the sports drink and 6687 ppm in the energy drink, calculated automatically by Empower 3 with dilution factors applied.

Benefits and Practical Application of the Method

• Fast analysis with retention times under 2 minutes.
• High sensitivity and reproducibility for quality control laboratories.
• Automated data acquisition and report generation reduce manual calculation errors.
• Low maintenance due to reduced surface adsorption of metal-sensitive analytes.

Future Trends and Potential Applications

The low-adsorption UPLC technology can be extended to other metal-sensitive organic acids and metabolites in food, pharmaceutical, and clinical matrices. Integration with high-throughput autosamplers and advanced data analytics could further streamline routine testing. Emerging detector technologies (e.g., mass spectrometry) combined with the described column hardware may expand method sensitivity and selectivity.

Conclusion

The developed UPLC-PDA method using Premier low-adsorption hardware offers a robust, rapid, and accurate solution for citric acid analysis in beverages. With superior peak shape, linearity, and precision, and automated data processing through Empower 3, this approach is well suited for routine quality control in food and beverage industries.

Reference

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