Diacetyl Analysis, Using SIFT-MS

Importance of the Topic

Diacetyl is a volatile organic compound with key roles in food flavoring and also a known occupational hazard in microwave popcorn production leading to bronchiolitis obliterans. Reliable and sensitive detection at low ppb levels is essential for worker safety, regulatory compliance and quality control in food industries.

Objectives and Study Overview

This study aims to evaluate the performance of a Selected Ion Flow Tube Mass Spectrometry instrument Voice200 in quantifying diacetyl over a wide concentration range (2 ppb to 20 ppm) and to assess its ability to discriminate diacetyl in the presence of isobaric interferences such as hexane and 3-pentanone.

Methodology

• Sampling and Preparation: One-liter Tedlar bags filled with nitrogen were spiked with headspace vapors of diacetyl, hexane or 3-pentanone.
• Serial Dilution: Diacetyl concentrations were prepared from 2 ppb up to 20 ppm in nitrogen-filled bags.
• Interference Testing: Each dilution series was spiked with approximately 0.5 ppm hexane and subsequently with 1.5 ppm 3-pentanone to evaluate potential isobaric overlaps.
• Analysis: Samples were introduced into the Voice200 SIFT-MS instrument for real-time quantification without additional calibration steps.

Used Instrumentation

• Syft Technologies Voice200 Selected Ion Flow Tube Mass Spectrometer
• Tedlar gas sampling bags (1 liter)
• Syft Technologies portable sample case for remote bag handling

Main Results and Discussion

• Linearity: Diacetyl response showed excellent linearity from 2 ppb to 20 ppm, confirming accurate quantification across five orders of magnitude.
• Interference Resistance: The addition of 0.5 ppm hexane and 1.5 ppm 3-pentanone did not compromise the linear response to diacetyl, demonstrating effective isobaric discrimination via reagent ion chemistry.
• Detection Capability: The instrument maintained low-ppb sensitivity with intrinsic quantitation, eliminating the need for extensive calibration.

Benefits and Practical Applications

• Real-Time Monitoring: Instantaneous results support on-site exposure assessment and process control.
• No Calibration Required: Intrinsically quantitative measurements simplify operation and reduce downtime.
• Wide Dynamic Range: Capability to detect from ppt to ppm levels addresses both trace monitoring and high-level analysis.
• Occupational Safety: Facilitates regular screening for diacetyl in production environments to protect worker health.

Future Trends and Opportunities

• Field Deployment: Integration with portable sampling systems for continuous workplace monitoring.
• Expanded VOC Coverage: Development of additional reagent ions to target a broader range of flavor and industrial compounds.
• Automation and Data Analytics: Coupling with software platforms for trend analysis, remote diagnostics and predictive risk assessment.
• Environmental and Food Quality Applications: Extension to ambient air safety studies, indoor air quality surveys and off-flavor detection in food processing.

Conclusion

The Voice200 SIFT-MS system provides a robust, sensitive and interference-resistant platform for diacetyl quantification over a wide concentration range. Its real-time capabilities, minimal calibration needs and portability make it a valuable tool for flavor analysis, industrial hygiene and food safety monitoring.

References

1. Belitz HD, Grosch W, Schieberle P Food Chemistry 3rd Ed. Springer 2004 546–547
2. Kanwal R et al Evaluation of flavorings-related lung disease risk at six microwave popcorn plants J Occup Environ Med 2006 48 149–157
3. Spanel P Ji YF Smith D SIFT studies of reactions of H3O+, NO+ and O2+ with aldehydes and ketones Int J Mass Spectrom Ion Processes 1997 165/166 25–37