Analysis of Sulfites in Food and Beverages Using Single Quadrupole Mass Spectrometer

Significance of the Topic

This section highlights the importance of monitoring sulfite levels in foods and beverages due to their widespread use as preservatives and potential health risks such as allergic reactions. Regulatory agencies require accurate quantification to ensure consumer safety and compliance with labeling thresholds.

Objectives and Study Overview

The study aimed to develop a rapid, safe, and solvent-free pretreatment method for the quantitative analysis of sulfites in various food matrices using a single quadrupole mass spectrometer. By adapting the FDA method C-004.03 and eliminating dichloromethane from the workflow, the approach streamlines sample preparation and simplifies quantification.

Methodology and Instrumental Setup

The analytical workflow involves the following steps:

• Extraction: Conversion of sulfites to hydroxymethylsulfonate (HMS) using a 0.2% formaldehyde solution in ammonium acetate at pH 4.5.
• Sample Preparation: Ultrasonic extraction for dried fruits and dilution for wine samples, followed by centrifugation to collect the supernatant.
• SPE Cleanup: C18 cartridges conditioned with methanol and formaldehyde solution; removal of lipids; derivatization by heating at 80°C for 30 minutes.
• LC–MS Analysis: Shimadzu Nexera X3 HPLC with InertSustain AX-C18 column (100×2.1 mm, 3 μm); mobile phases of 2 mM ammonium formate/0.1% formic acid and 0.1% formic acid in acetonitrile; gradient elution (30–100% B); flow rate 0.2 mL/min; column temperature 30°C; injection volume 2 μL. Detection on LCMS-2050 operated in ESI/APCI negative mode using DUIS™ and SIM monitoring of m/z 111 and 113.

Main Results and Discussion

The method demonstrated excellent linearity (R2>0.999) over a calibration range of 0.02–2 ppm HMS. Quantification of sulfite levels in dried fruits (raisin, pineapple, mango) and wines (red, white) yielded results consistent with regulatory limits. Recovery tests in blank matrices showed rates between 95.4% and 103.5%, confirming accuracy and precision at the 10 mg SO2/kg threshold.

Benefits and Practical Applications

The protocol offers rapid throughput, avoids regulated solvents, and ensures reliable quantification of sulfites for quality control in food manufacturing and regulatory laboratories. Its simplicity facilitates routine screening while maintaining compliance with FDA guidelines.

Future Trends and Potential Applications

Integration with high-resolution mass analyzers could expand analyte coverage. Automation of SPE and derivatization steps may increase throughput. Application to complex matrices beyond fruits and beverages and coupling with advanced data analysis tools will further enhance food safety monitoring.

Conclusion

The developed single quadrupole LC–MS method provides a safe, efficient, and accurate approach for sulfite analysis in food and beverage samples. Elimination of dichloromethane and successful validation support its adoption in routine quality assurance workflows.

References

1. Carlos, K. S., & de Jager, L. S. (2017). Determination of sulfite in food by liquid chromatography tandem mass spectrometry: Collaborative study. Journal of AOAC International, 100(6), 1785–1794.
2. U.S. Food and Drug Administration (2021). Method number: C-004.03, Determination of Sulfites in Food using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).