LC-MS/MS method development for sulfites in food and beverage

Importance of the Topic

Sulfites serve as antioxidants and bleaching agents widely used in foods and beverages but can trigger allergy-like reactions and are subject to regulatory labeling above 10 mg/kg. Accurate, rapid quantification methods are vital for consumer safety and compliance with FDA and international standards.

Objectives and Study Overview

This study aimed to develop a fast, robust LC-MS/MS method for quantifying sulfites in foods and beverages. The method is based on recent FDA guidelines, converting sulfite to hydroxymethylsulfonate (HMS) for sensitive detection and achieving a shorter analysis time.

Methodology

Sample extraction employs 0.2% formaldehyde in ammonium acetate solution to stabilize sulfite as HMS. For dried fruits, a two-step extraction with blending, shaking, sonication, and centrifugation is applied. Wine samples are diluted directly with derivatization solution. Solid phase extraction with a C18 cartridge removes interfering matrix components, followed by heat-induced conversion of adducts to HMS.

Used Instrumentation

• Nexera 40 X3 UHPLC system
• SeQuant ZIC HILIC column (150 mm x 2.1 mm, 5 μm)
• LCMS-8050 triple quadrupole mass spectrometer with ESI negative mode
• Mobile phases: ammonium acetate in acetonitrile-water gradients

Main Results and Discussion

Optimization of MRM transitions and probe position extended quantitation linearity to 20 ppm and reduced analysis time from 24 to 12 minutes. Calibration curves for HMS showed excellent linearity and reproducibility. Recovery tests in dried fruits achieved 84.9% to 99.2% at 5 μg/g and 91.2% to 96.3% at 10 μg/g. Red and white wines spiked at 1 to 10 μg/g yielded recoveries between 95.2% and 104.0%, demonstrating reliable performance at regulatory thresholds.

Benefits and Practical Applications

The developed method delivers rapid, sensitive sulfite quantification across diverse matrices, supporting quality control in food production, regulatory compliance, and assurance of labeling accuracy. Its short runtime and minimal sample prep enhance laboratory throughput and cost efficiency.

Future Trends and Potential Applications

Opportunities include extension to other food matrices, integration with high-throughput automated platforms, ambient ionization techniques, and miniaturized portable MS systems for on-site testing. Further standardization could facilitate global regulatory harmonization.

Conclusion

A robust LC-MS/MS protocol was established for rapid, accurate sulfite analysis in foods and beverages. It meets current regulatory requirements, offers high sensitivity and recovery, and reduces analysis time, making it an effective tool for food safety laboratories.

References

[1] U.S. Food Drug Administration (2018). Code of Federal Regulations Part 101.100(a)(4). Office of the Federal Register.
[2] Carlos KS and de Jager LS (2017). Determination of sulfite in food by LC-MS/MS: Collaborative study. Journal of AOAC International, 100(6):1785–1794.
[3] U.S. Food Drug Administration (2021). Method C-004.03 Determination of Sulfites in Food using LC-MS/MS.