Rapid and sensitive quantitative method for screening of additives in beverages

Significance of the Topic

The analysis of food additives in beverages is critical for compliance with regulatory requirements and for safeguarding consumer health. A unified screening method that can detect multiple classes of additives in a single run enhances laboratory responsiveness and efficiency. By combining detectors that cover both chromophoric and nonchromophoric compounds, analysts can ensure a comprehensive profile of sweeteners, preservatives, and stimulants in complex matrices.

Objectives and Study Overview

The primary goal was to develop and validate a rapid quantitative UHPLC method capable of simultaneous determination of ten common beverage additives across three functional classes: sweeteners, preservatives, and stimulants. The study evaluated method accuracy and precision by analyzing multiple commercial soft drink types and by participating in an interlaboratory proficiency test scheme.

Used Instrumentation

• Thermo Scientific Vanquish Flex Binary UHPLC system
• Vanquish Binary Pump F and 150 µL static mixer
• Vanquish Split Sampler FT with 25 µL injection loop
• Vanquish Column Compartment H with passive pre-heater
• Hypersil GOLD C18 column (4.6×250 mm, 5 µm)
• Vanquish Diode Array Detector FG (wavelengths 200–244 nm)
• Vanquish Charged Aerosol Detector F (evaporation temp 35 °C)
• Chromeleon 7.3.2 Chromatography Data System

Methodology and Sample Preparation

Standards for ten additives were prepared as individual primary solutions (1–20 g/L) with optimized solvents to address solubility differences. Three mixed working solutions were generated to match routine sample demands. Beverage samples including carbonated drinks, energy drinks, teas, and infusions were centrifuged, diluted (typically 5×), acidified when needed, and degassed for carbonates. Calibration curves covering 1–100 mg/L were built by automated variable volume injections (0.2–20 µL) using split sampler programming. Chromatography ran at 1.0 mL/min over 20 minutes, with mobile phases of water containing 10 mM ammonium acetate (A) and methanol (B) at 40 °C. UV detection monitored chromophoric analytes at multiple wavelengths, while CAD provided universal detection for nonchromophoric compounds. Data processing and automatic quality checks were managed in Chromeleon CDS.

Results and Discussion

• Linearity: All ten additives showed excellent correlation (R2 > 0.9975) using quadratic 1/x weighting.
• Limits of Quantification: System LOQs ranged from 1 to 2 mg/L, method LOQs from 5 to 10 mg/L.
• Precision and Accuracy: Quality control samples at LOQ and mid-range levels exhibited deviations under ±15% and ±6% respectively. Automated calibration injection reduced manual errors.
• Caffeine Label Verification: Measured caffeine in eight commercial beverages deviated less than 5% from label claims.
• Spike and Recovery: Recovery tests across diverse matrices yielded averages between 93% and 103% with RSDs below 5% for all additives.
• Proficiency Testing: Results for two beverage test samples produced z-scores below 2 for all analytes, meeting interlaboratory acceptance criteria.

Benefits and Practical Applications

• Single-injection, multi-class screening simplifies quality control workflows.
• Automated calibration and split sampler injection minimize hands-on time and human error.
• Combination of UV and CAD extends detection scope to compounds lacking chromophores.
• Method is robust for diverse beverage matrices and fits high throughput laboratories.

Future Trends and Opportunities

Continued advances in universal detectors may allow expansion of target lists to emerging additives and contaminants. Integration with high-resolution mass spectrometry or advanced data analytics could enhance specificity and traceability. Automated sample preparation robotics and cloud-based data management are expected to further accelerate routine screening in industrial and regulatory laboratories.

Conclusion

The presented UHPLC method combining diode array and charged aerosol detection offers a cost-effective, sensitive, and comprehensive approach for simultaneous quantification of major beverage additives. Demonstrated accuracy, precision, and proficiency test performance confirm its suitability for routine quality control in the food and beverage industry.

Reference

1. LGC AXIO Proficiency Testing Quality in Beverages Scheme