High-Speed Analysis of Artificial Colorant

Significance of the Topic

The monitoring of artificial colorants in food products is critical for consumer safety, regulatory compliance, and quality assurance. Rapid and reliable methods are required to detect trace levels of synthetic dyes that may pose health risks or be subject to strict labeling requirements.

Objectives and Overview of the Study

This study aimed to develop and validate a high-speed liquid chromatography–mass spectrometry (LC-MS) method capable of separating and identifying twelve commonly used artificial colorants in a single run. The focus was on achieving fast analysis times while maintaining sensitivity and selectivity for negative ion detection of sulfone and carboxyl functional groups.

Methodology and Used Instrumentation

A standard mixture of each colorant at 10–100 mg/L was prepared in aqueous solution.

• Instrument: Shimadzu Prominence UFLC system coupled to LCMS-2010EV
• Column: Shim-pack XR-ODS, 50 mm × 2.0 mm I.D., maintained at 40 °C
• Mobile phase: (A) 20 mmol/L ammonium acetate buffer (pH 4.7); (B) 20 mmol/L ammonium acetate/acetonitrile (1:1, v/v)
• Gradient: B increased from 10% to 100% over 0–5 minutes
• Flow rate: 0.5 mL/min; Injection volume: 5 µL
• Detection: Dual ion source (DUIS) in negative ion mode, scan acquisition

Main Results and Discussion

The optimized gradient allowed baseline separation of all twelve dyes in under five minutes. Each compound produced a distinct deprotonated molecular ion (m/z) corresponding to its known structure:

• Tartrazine (m/z 467)
• Amaranth (m/z 537)
• Indigo carmine (m/z 421)
• New coccine (m/z 537)
• Sunset yellow FCF (m/z 407)
• Allura red AC (m/z 451)
• Fast green FCF (m/z 763)
• Brilliant blue FCF (m/z 747)
• Acid red (m/z 557)
• Phloxine B (m/z 784.5)
• Erythrosine (m/z 834.5)
• Rose bengal (m/z 972.5)

The total ion chromatogram exhibited sharp peaks with minimal co-elution, demonstrating high resolution and reproducibility. The negative-ion mode enhanced detection sensitivity for sulfone and carboxyl groups, typical in many food colorants.

Benefits and Practical Applications

This rapid LC-MS approach offers several advantages:

• High throughput: complete profiling in under five minutes per sample
• Robust quantitation: clear peak separation and consistent retention times
• Broad applicability: suitable for regulatory laboratories, quality control in food production, and research settings
• Minimal sample preparation: direct analysis of standard mixtures without extensive cleanup

Future Trends and Potential Applications

Advancements may include integration with high-resolution mass spectrometry to improve structural elucidation, miniaturized flow systems to reduce solvent consumption, and expanded multiplexed assays combining colorants with other food additives or contaminants. Machine learning algorithms could further streamline data processing and peak identification.

Conclusion

A high-speed UFLC-MS method was successfully established for the simultaneous separation and detection of twelve artificial colorants. The technique provides a fast, reliable, and sensitive platform for routine quality control and regulatory compliance in the food industry.

References

• Shimadzu Corporation. Application Data Sheet LAAN-A-LC-E093. October 2007.