SERS Detection of Brilliant Blue

Importance of the Topic

Brilliant Blue FCF is the most widely used synthetic blue food dye worldwide. While generally regarded as safe, its strong fluorescence and weak Raman scattering make on-site detection in complex food and beverage matrices challenging. This study presents a rapid, portable Surface-Enhanced Raman Spectroscopy (SERS) method using Metrohm Instant SERS Analyzer (MISA) to overcome fluorescence interference and achieve reliable identification of Brilliant Blue.

Objectives and Study Overview

The primary objective is to develop and validate a simple workflow for detecting Brilliant Blue in a flavoured drink mix. The study outlines both a direct SERS measurement and an optimized liquid-liquid extraction protocol to enhance signal quality in complex samples.

Methodology

• Reference Spectrum Creation: A 500 µg/mL aqueous Brilliant Blue standard was analyzed with gold nanoparticles (Au NPs) to build a SERS reference library entry.
• Direct Analysis: 100 mg of drink mix was dissolved in water, combined with Au NPs and NaCl, shaken, and measured by MISA.
• Extraction Protocol: Sample was treated with benzethonium chloride surfactant, extracted into chloroform, vortexed, phase-separated, and the chloroform layer was evaporated. The residue was reconstituted with Au NPs and NaCl for SERS measurement.

Used Instrumentation

• Metrohm MISA Advanced Portable SERS Analyzer
• MISA Vial Attachment
• Au Nanoparticle ID Kit (gold colloid, disposable pipettes, sample vials)
• Hot Plate for solvent evaporation

Main Results and Discussion

• Direct SERS scans produced partial peak matching but were compromised by matrix fluorescence and background signals.
• The chloroform extraction significantly improved spectrum fidelity, yielding clear peaks that closely matched the reference library.
• Stacked spectral comparisons confirmed enhanced peak resolution and reliable identification of Brilliant Blue after cleanup.

Benefits and Practical Applications

• Field-deployable analysis without extensive laboratory equipment.
• Minimal sample preparation reduces time and resource requirements.
• Effective detection of fluorescent dyes in complex food matrices supports quality control and regulatory verification.

Future Trends and Applications

• Integration with cloud-based spectral libraries for automated, real-time reporting.
• Extension of the workflow to other dyes and contaminants using tailored extraction chemistries.
• Development of automated sample preparation modules to further streamline field testing.

Conclusion

The study demonstrates that combining MISA’s portable SERS capabilities with a simple surfactant-assisted chloroform extraction overcomes fluorescence challenges and enhances detection of Brilliant Blue in complex food matrices. This approach delivers rapid, reliable on-site screening without reliance on bulky laboratory instrumentation.