Negative Mode Detection of Sulfonated Azo Colourants in Sweets/Candies using the MALDI- 8030 Dual Polarity Benchtop MALDI-TOF Mass Spectrometer

Importance of Sulfonated Azo Dye Analysis

Detection of sulfonated azo dyes in food is essential to ensure consumer safety and regulatory compliance. These dyes are widely used for their stability and low cost but have been linked to adverse health effects in sensitive populations, prompting stringent controls worldwide.

Study Objectives and Overview

This study evaluates the MALDI-8030 dual polarity benchtop MALDI-TOF mass spectrometer for qualitative detection of regulated sulfonated azo colourants in commercial sweets. The workflow combines selective ion-pair extraction with negative ion mode MALDI-TOF analysis to identify dyes in single candy samples.

Methodology and Instrumentation

The dye extraction uses benzyltributylammonium bromide at pH above 8 and chloroform to form ion pairs with sulfonated azo dyes. After phase separation, extracts are mixed with 9-aminoacridine matrix and analyzed in negative ion mode on the MALDI-8030 bench-top linear MALDI-TOF mass spectrometer.

Results and Discussion

Standard dyes yielded clear monoisotopic peaks with excellent mass accuracy: Sunset Yellow FCF at m/z 407.071 (–0.07 Da), Allura Red AC at m/z 451.008 (+0.019 Da), Tartrazine at m/z 467.017 (–0.02 Da), and Brilliant Blue FCF at m/z 747.152 (–0.001 Da). Candy extracts produced spectra consistent with expected colour profiles, confirming selective extraction and reliable identification.

Benefits and Practical Applications

• Rapid qualitative screening of regulated azo dyes in food samples
• High resolution and mass accuracy in negative ion mode
• Cost-effective benchtop MALDI-TOF platform for QA/QC laboratories
• Simplified sample preparation with minimal solvents and reagents

Future Trends and Opportunities

Opportunities include extending to quantitative workflows, broadening to additional dye classes and complex food matrices, integrating automated sample handling, and combining with liquid extraction–MS techniques to enhance throughput and regulatory monitoring.

Conclusion

The described approach demonstrates a fast, robust method for detecting sulfonated azo dyes in confectionery, aligning with regulatory requirements and supporting quality control in the food industry.

References

• Arroyo Negrete M.A. et al. Anal Bioanal Chem 411 5833–5843 (2019)