Analysis of Residual Ethylene Oxide in Medical Devices

Importance of the Topic

Ethylene oxide (EO) is a widely used sterilant for heat-sensitive medical devices. Traces of residual EO can pose toxicological risks to patients and must be controlled below strict regulatory thresholds. Reliable quantification of residual EO is therefore essential for ensuring device safety and regulatory compliance.

Study Objectives and Overview

This application note describes the development and validation of a headspace gas chromatography–flame ionization detection (HS-GC-FID) method for measuring residual EO in medical device materials. The study aims to achieve sensitive, accurate, and reproducible analysis within a single 30-minute chromatographic run.

Used Instrumentation

• Gas chromatograph: Shimadzu Nexis GC-2030
• Detector: Shimadzu FID-2030 flame ionization detector
• Headspace sampler: Shimadzu HS-20
• Column: SH-PolarWax (30 m × 0.53 mm I.D., 2.00 µm film thickness)

Methodology

The method employs static headspace sampling combined with GC-FID. Key parameters include:

• Oven program: 40 °C (5 min), ramp 30 °C/min to 200 °C (20 min)
• Headspace equilibration: 70 °C, 30 min shaking at level 3
• Sample pressurization: 100 kPa for 1 min, loading 1 min
• Injection: 1 mL split 1:20
• Carrier gas: nitrogen, constant linear velocity 30 cm/s
• FID settings: 250 °C, H₂ 32 mL/min, air 200 mL/min, makeup N₂ 24 mL/min

Main Results and Discussion

The method achieved clear separation of EO and propylene oxide (internal standard) with retention times under 10 min. Calibration was linear over the relevant concentration range, with correlation coefficients above 0.999. The method detection limit for EO was below typical regulatory limits, and repeatability studies showed relative standard deviations under 5%.

Matrix interference was minimal due to the polar wax column, and the total analysis time of 30 min supports high sample throughput in quality control laboratories.

Benefits and Practical Applications

• High sensitivity and specificity for EO in diverse device materials
• Robust and reproducible performance suitable for routine QC testing
• Rapid turnaround supports fast release of medical products
• Compliance with regulatory guidelines for residual sterilants

Future Trends and Potential Applications

Advancements may include coupling headspace sampling with mass spectrometric detection to enhance specificity and lower detection limits. Automated sample preparation and real-time monitoring systems could further streamline EO residue testing. Emerging green alternatives to EO sterilization may also drive new analytical requirements.

Conclusion

The described HS-GC-FID method provides a robust, sensitive, and efficient approach for quantifying residual ethylene oxide in medical devices. Its performance meets regulatory demands and supports reliable quality control in manufacturing environments.

Reference

• Shimadzu Corporation. Application News G336: Analysis of Residual Ethylene Oxide in Medical Devices. First Edition: September 2022.