Analysis of Residual Ethylene Oxide in Medical Devices - No. 363

Significance of Topic

Ethylene oxide (EO) is a critical sterilizing agent for medical devices that are sensitive to heat and moisture. However, residual EO and related compounds pose health risks if they exceed safe limits. Accurate, reliable monitoring of EO residues ensures patient safety and regulatory compliance.

Objectives and Study Overview

This study aims to develop and validate a headspace gas chromatography method with flame ionization detection (GC-FID) for quantifying residual EO and propylene oxide (PO) in sterilized medical devices. The method emphasizes simplicity, reproducibility, and suitability for quality control laboratories.

Methodology and Instrumentation

Sample Preparation:

• Devices placed in 10 mL headspace vials
• Equilibration at 75 ˚C for 30 minutes under 100 kPa
• Vial shaking level set to 3 for consistent gas release

Chromatographic Conditions:

• Column: SH-PolarWax, 30 m × 0.53 mm ID, 2 µm film
• Oven program: 40 ˚C (5 min) → 200 ˚C at 30 ˚C/min (20 min)
• Carrier gas: Nitrogen at 30 cm/s (constant linear velocity)
• Injection: 1 mL split (1:20)
• Run time: ~30.3 min

Used Instrumentation

• GC System: Nexis™ GC-2030
• Detector: FID-2030 Flame Ionization Detector (250 ˚C)
• Headspace Sampler: HS-20 with heated transfer line (75 ˚C)
• Makeup gas: Nitrogen (24 mL/min); Detector gases: H2 (32 mL/min), Air (200 mL/min)

Main Results and Discussion

The method achieved baseline separation of EO, PO (internal standard), and potential interferences. Calibration was linear over the target concentration range with correlation coefficients > 0.999. Limits of detection and quantification met pharmacopeial requirements. Precision (RSD < 5 %) and accuracy (recovery within 95–105 %) were demonstrated across multiple device matrices.

Retention times were consistent, ensuring reliable identification. The total analysis time under 31 minutes allows moderate throughput suitable for routine quality control.

Benefits and Practical Applications

• Robust quantification of EO residues in various polymeric devices
• Compliance with regulatory guidelines for residual sterilants
• Simple sample handling and minimal preparation steps
• Adaptable to different headspace-capable GC platforms

Future Trends and Potential Applications

Advances may include coupling with mass spectrometry for enhanced sensitivity, automated sample preparation to increase throughput, and miniaturized headspace interfaces for on-site testing. Emerging green technologies could replace or reduce EO usage, necessitating methods for alternate sterilant residues.

Conclusion

The presented GC-FID headspace method provides a validated, reproducible approach to monitor residual EO in sterilized medical devices. Its simplicity and compliance with regulatory standards make it an effective tool for quality assurance in medical device manufacturing.

Reference

Shimadzu Corporation. Analysis of Residual Ethylene Oxide in Medical Devices. Application News 01-00140. First Edition, September 2022.