Ethylene Oxide and 2-Chloroethanol in Various Rice Samples by Dynamic Headspace and GC- MS/MS

Importance of the Topic

This study addresses the critical need to monitor ethylene oxide (EO) residues and its byproduct 2-chloroethanol (2-CE) in rice. EO fumigation is widely used to control pests in stored grains, but trace residues pose health concerns. Sensitive detection of both EO and 2-CE ensures compliance with food safety regulations and protects consumer health.

Objectives and Study Overview

The main aim was to develop and validate a rapid, sensitive method for quantifying EO and 2-CE in various rice types. Using dynamic headspace sampling coupled with triple-quadrupole GC-MS/MS, the study evaluated method performance in terms of limit of quantitation, linearity, repeatability, and recovery. Spiked rice samples at three concentration levels (10, 25, 100 ng/g) were analyzed to assess accuracy across matrices.

Used Instrumentation

• GC-MS/MS system: Shimadzu GCMS-TQ8050 NX
• Headspace autosampler: HS-20 NX Trap model
• Column: SH-I-624 Sil MS (60 m × 0.25 mm ID × 1.4 µm)
• Carrier and headspace gas: Helium

Methodology and Analytical Conditions

Dynamic headspace trapping at –20 °C followed by desorption at 70 °C enabled enrichment of volatiles without complex extraction. A split injection (ratio 15:1) and linear velocity control maximized chromatographic resolution. MS/MS transitions for EO and 2-CE were optimized, with ion source at 250 °C and interface at 235 °C.

Main Results and Discussion

The limit of quantitation for both analytes was 5 ng/g, with signal-to-noise ratios >10. Repeatability (n=5) yielded area RSDs of 4.6 % for EO and 5.6 % for 2-CE. Calibration curves (5–100 ng/g) showed excellent linearity (R2 > 0.997). Recovery experiments in four rice varieties demonstrated 70–130 % recovery without matrix-matched calibration. No native residues were detected in unspiked samples.

Practical Benefits and Applications

• Simplified sample preparation by dynamic headspace, eliminating liquid extraction.
• High sensitivity and repeatability suitable for trace analysis.
• Applicable to routine QA/QC testing in food safety laboratories.

Future Trends and Potential Applications

Expanding the method to other grain matrices and foodstuffs can broaden its utility. Integration with automated sample preparation and alternative detection technologies (e.g., high-resolution MS) may further enhance throughput and selectivity. Adoption of green solvents and trap materials could improve sustainability.

Conclusion

The developed dynamic headspace GC-MS/MS method provides a robust, sensitive, and efficient approach for monitoring EO and 2-CE in rice. High linearity, low detection limits, and satisfactory recoveries demonstrate its suitability for regulatory compliance and quality assurance.

Reference

1. Ting E., Ethylene Oxide and 2-Chloroethanol Analysis in Instant Noodles by Dynamic Headspace and GC-MS/MS, Shimadzu Application News No. 04-AD-0299-EN, 2024.