Analysis of Residual Ethylene Oxide in Medical Devices by Headspace Gas Chromatography

Importance of the Topic

Residual ethylene oxide in sterilized medical devices can pose health risks if concentrations exceed specified limits. Consistent quantification ensures patient safety and regulatory compliance under standards such as ISO 10993-7 and JIS T 0993-7.

Objectives and Study Overview

This study aimed to develop and validate a headspace gas chromatography method for exhaustive extraction and quantification of residual ethylene oxide in medical device materials. The work addressed international and Japanese standards for residual limits and outlined a procedure for both sheet-type and tube-type samples.

Methodology and Instrumentation

Analysis used headspace GC under standard conditions. Key parameters:

• Headspace sampler: Shimadzu HS-20
• Gas chromatograph: Nexis GC-2030 with FID-2030 detector
• Column: StabilwaxTM (30 m×0.53 mm I.D., 2.00 µm)
• Carrier gas: N₂ at 30 cm/s constant linear velocity
• Temperature program: 40 °C (5 min) to 200 °C at 30 °C/min (total 30.33 min)
• Headspace equilibration: oven 70 °C, vial 10 mL, sample equilibration 180 min

Sample preparation:

• Internal standard: propylene oxide at 0.5 µg/mL in ethanol
• Matrix: 0.5 g of bandage or catheter pieces per 10 mL vial
• Extraction: exhaustive ethanol extraction followed by sealing and headspace analysis

Main Results and Discussion

System suitability tests demonstrated resolution >3.3 between EO and PO, tailing factors <1.1, and calibration linearity (r=0.9991) over 0.4–2.0 µg/mL with RSD <3.5 %. LOD and LOQ were ~0.05 and 0.16 µg/mL respectively. Residual EO in bandage averaged 1.97 µg per 0.5 g, while catheter averaged 0.39 µg per 0.5 g, both within regulatory thresholds.

Benefits and Practical Applications

The validated HS-GC method offers high sensitivity, reproducibility, and throughput for quality control of sterilized medical materials. It supports risk management by ensuring residual EO remains within safe limits and facilitates compliance audits for device manufacturers.

Future Trends and Possible Applications

Advances may include integration with mass spectrometric detectors for enhanced selectivity, automated sample handling to reduce variability, miniaturized headspace systems for on-site monitoring, and adoption of greener solvents. Ongoing work on method transfer to diverse device geometries and real-time monitoring aligns with industry 4.0 objectives.

Conclusion

The HS-GC approach meets JIS and ISO requirements for exhaustive extraction and quantitation of residual ethylene oxide. The Shimadzu HS-20/GC-2030 system proved reliable for medical device analysis, supporting both regulatory compliance and patient safety.