Fast, reproducible UHPLC-UV determination of dyes found in beverages

Importance of the Topic

Food dyes are extensively used to enhance the appearance of beverages. Rapid and reliable analysis of these dyes is critical for quality control, regulatory compliance, and consumer safety in the food and beverage industry.

Study Aims and Overview

The main objective was to demonstrate a seamless transfer of a UHPLC-UV method for nine common food dyes from the Thermo Scientific™ UltiMate™ 3000 RS system to the Vanquish™ Flex UHPLC system using an Acclaim™ PolarAdvantage II column. The study aimed for complete separation in under five minutes while maintaining high retention time precision.

Methodology and Instrumentation

The analysis employed reversed-phase UHPLC with UV detection. Key components included:

• Column: Acclaim PolarAdvantage II, 3 µm, 75 × 3 mm
• Mobile phase A: 20 mM ammonium phosphate, pH 8.8 (100% water)
• Mobile phase B: 20 mM ammonium phosphate, pH 8.8/acetonitrile (50:50 v/v)
• Gradient: 88% A / 12% B (0 min) to 0% A / 100% B (3.5 min), hold to 4.5 min, return to initial by 4.6 min
• Flow rate: 0.71 mL/min; column temperature: 30 °C; injection volume: 3 µL; detection at 254 nm

Instrumentation platforms:

• UltiMate 3000 RS system: LPG-3400RS pump, WPS-3000TRS autosampler, TCC-3000RS oven, DAD-3000RS detector (13 µL flow cell)
• Vanquish Flex system: Quaternary Pump F, Split Sampler FT, Column Compartment H with active pre-heater, Diode Array Detector HL (2 µL flow cell)
• Software: Chromeleon CDS 7.2 SR4

Sample preparation involved dissolving each dye to 1 mg/mL in mobile phase A, then combining to a mixed standard of 10 µg/mL per dye.

Main Results and Discussion

Both systems achieved full resolution of all nine dyes within approximately four minutes. Retention times were comparable between instruments, requiring no gradient delay volume adjustments. The Vanquish Flex system exhibited significantly improved retention time precision, with up to an 80% reduction in %RSD for indigo carmine, attributed to advanced SmartInject autosampler technology and pump improvements.

Benefits and Practical Applications

The method offers:

• Rapid analysis of multiple food dyes in under five minutes
• High retention time precision and reproducibility (low %RSD)
• Seamless transfer between UHPLC systems without revalidation
• Enhanced data confidence and extended column lifetime

Future Trends and Opportunities

Potential developments include integration with mass spectrometric detection for confirmatory analysis, further reduction in analysis time through ultrafast gradients, expanded application to other food additives, and increased automation coupled with digital sample tracking for high-throughput quality control.

Conclusion

The Acclaim PolarAdvantage II column paired with the Vanquish Flex UHPLC system delivers a fast, robust, and precise method for the determination of nine food dyes in beverages. Method transfer from legacy systems is straightforward, and improvements in instrumentation significantly enhance analytical performance.