Determination of Ethylene Chloride Hydrin Residue

Ethylene Chlorohydrin (HOCH₂CH₂Cl) Residual Analysis – GC-MS Method – TS EN ISO 10993-7 Annex B

1. What is Ethylene Chlorohydrin (ECH)?

Ethylene Chlorohydrin is a toxic by-product formed after ethylene oxide (EO) sterilization of medical devices. With the chemical formula HOCH₂CH₂Cl, ECH is classified as a hazardous compound due to its nephrotoxic, hepatotoxic, and neurotoxic effects.

2. Why is ECH Residual Testing Necessary?

EO sterilization may produce ECH and ethylene glycol residues as secondary products.
ECH is more stable than EO and may remain longer on the surface of devices.
Therefore, measuring ECH residuals is essential for ensuring patient safety and regulatory compliance.

3. ISO 10993-7 Annex B – Residual Limits

Device Contact Duration	Maximum ECH Residual (mg/device)
Short-term contact (<24 h)	≤ 9 mg
Long-term contact (>24 h)	≤ 4 mg
Implantable devices	≤ 0.5 mg

4. GC-MS Method for ECH Residual Determination

Sample Preparation

Devices are aerated post-sterilization.
Extracted using ultrapure water or water-methanol under sterile conditions.

GC-MS Analytical Conditions (Example)

Parameter	Setting
Column	DB-Wax, 30 m × 0.25 mm × 0.25 µm
Carrier Gas	Helium
Injection Mode	Splitless
Ionization Mode	EI, 70 eV
Target Ions	m/z 64, 49 (ECH)

Calculation

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

5. Importance of ECH Residual Testing

Ensures safety of sterilized medical devices
Required for CE Marking, FDA submissions and ISO 13485 compliance
Supports biocompatibility and toxicological risk assessment

6. TTS Laboratory Services Support

At TTS Laboratory Services, we perform ECH residual analysis in compliance with ISO 10993-7 Annex B, using validated GC-MS techniques.

✔ EO, ECH, EG residual quantification
✔ Sterilization validation & aeration verification
✔ ISO/IEC 17025-compliant reporting
✔ Biocompatibility & toxicological risk evaluation