Ethylene Oxide (C₂H₄O) Residual Analysis – TS EN ISO 10993-7 Annex B

1. What is Ethylene Oxide Residual Analysis?

Ethylene oxide residual analysis is performed to determine the remaining levels of ethylene oxide (EO) and its toxic by-products such as ethylene chlorohydrin (ECH) and ethylene glycol (EG) after sterilization of medical devices.
This procedure is defined in TS EN ISO 10993-7 Annex B, and it is mandatory for devices with patient contact.

2. Why is Ethylene Oxide Hazardous?

• Classified as carcinogenic and mutagenic (IARC Group 1).

• Causes irritation on respiratory system, eyes, and skin.

• Residual EO, ECH, or EG on medical devices can lead to serious toxicity in patients.

3. Limit Values According to ISO 10993-7 Annex B

4. Test Procedure for EO Residual Analysis

Step 1: Sample Preparation

• Devices are aerated after sterilization.

• Sample size determined based on surface area or volume.

Step 2: Extraction

• Samples are extracted with suitable solvent in sealed vials.

Step 3: Gas Chromatography (GC-FID or GC-MS)

• Column: PEG / DB-Wax capillary

• Detector: FID or Mass Spectrometry

• Calibration using EO, ECH, EG standards

Step 4: Calculation

$$Residual (mg/device) = \\\\frac{C \\\\times V \\\\times DF}{N}$$

5. Importance of EO Residual Testing

• Ensures post-sterilization safety

• Required for CE marking, FDA approval, and ISO 13485 compliance

• Prevents toxic exposure in patients

• Essential for sterilization validation and requalification

6. TTS Laboratory Services

At TTS Laboratory Services, we offer EO residual analysis according to TS EN ISO 10993-7 Annex B using validated GC-FID / GC-MS methods.

• EO, ECH, EG quantification

• Sterilization validation support

• Toxicological risk assessment

• ISO/IEC 17025-compliant reporting