Simultaneous Analysis of Synthetic Colorants, Including Red No. 3, Using Integrated LC System

Importance of the topic

The accurate and efficient analysis of synthetic food colorants is essential for ensuring product safety, complying with international regulations, and maintaining consumer trust. Simultaneous determination of multiple additives reduces analytical time and cost, while supporting quality assurance in food and beverage industries.

Objectives and Study Overview

This work demonstrates the development and validation of a liquid chromatography method for the simultaneous separation and quantification of twelve synthetic tar colorants approved in Japan, including Red No. 3. The study highlights the use of an integrated LC system and dedicated software to streamline method optimization and real-sample analysis.

Methodology and Instrumentation

• Instrument: Integrated LC i-Series (LC-2070C 3D).
• Column: Shim-pack NovaCore C18-HB core-shell column (100 mm × 3.0 mm I.D., 2.6 µm), featuring organic silica hybrid material with pH tolerance of 1–12.
• Software: LabSolutions MD for automated gradient and solvent composition optimization.
• Analytical conditions: 40 °C column oven; injection volume 3 µL; mobile phase A ­– 20 mmol/L ammonium acetate; mobile phase B – acetonitrile/methanol (80/20, v/v); flow rate 0.6 mL/min; gradient from 5 % to 95 % B over 10 min; UV detection at 254 nm.

Main Results and Discussion

Screening of organic solvent composition revealed that 20 % methanol in acetonitrile provided baseline resolution of critical peak pair Phloxine B (R104) and Acid Red 106 (R106) while maintaining a short run time. The Shim-pack NovaCore C18-HB column delivered sharp peaks and stable retention under neutral to basic conditions. LabSolutions MD automated the creation of analytical schedules across eleven solvent ratios, significantly reducing manual preparation and minimizing human error.
Application of the optimized method to real samples—including sugar candy, tablet candy (ramune), carbonated melon soda, and shaved ice syrup—successfully detected and quantified target colorants at the expected retention times without interference.

Benefits and Practical Applications

This workflow accelerates method development in routine quality control laboratories by combining a robust core-shell column, an integrated LC platform, and software-driven optimization. It supports regulatory compliance for food additives and can be adapted to various matrix types with minimal revalidation effort.

Future Trends and Potential Applications

Further enhancements may involve coupling with mass spectrometry for increased sensitivity and selectivity, implementing machine-learning algorithms for predictive method optimization, and extending the approach to natural and emerging colorants. Integration with online sample preparation modules could further improve throughput.

Conclusion

An efficient, reliable method for simultaneous analysis of twelve synthetic tar colorants was established using the i-Series LC system, Shim-pack NovaCore C18-HB column, and LabSolutions MD software. The approach offers high resolution, broad pH compatibility, and streamlined method development, meeting the demands of modern food analysis laboratories.

Reference

• Shimadzu Corporation. Simultaneous Analysis of Synthetic Colorants, Including Red No. 3, Using Integrated LC System. Application News 01-00935-EN, First Edition, Sep. 2025.