Technical Requirements for Parametric Release in EO Sterilization
Guidelines based on GB/Z 44877-2024 and GB 18279-2023
1. Equipment Control and Monitoring Capabilities
In addition to the requirements of GB 18279-2023 Chapter 10, the equipment must possess the following monitoring capabilities for parametric release:
- Airflow Management: Pre-conditioning rooms, sterilizers, and aeration rooms must be equipped with air circulation devices, anemometers, or other measures to monitor internal airflow.
- Humidity: Direct measurement of chamber humidity during the treatment phase.
- Concentration: Direct measurement of Ethylene Oxide (EO) concentration at specified intervals during exposure.
- Temperature: Monitoring at a minimum of two independent locations within the chamber.
All monitoring and recording systems must be defined, characterized, and documented. Sensor placement must be representative of the actual chamber state.
2. Critical Parameter Specifications
2.1 Humidity Monitoring
Humidity can be measured as Relative Humidity (RH) or Absolute Humidity.
- Relative Humidity: Typically measured using capacitance film technology to determine vapor pressure density at a given temperature.
- Absolute Humidity: Measures water concentration in a specific volume of air, often using spectroscopic techniques.
- Calibration: Electronic RH sensors (capacitance film) should be calibrated using saturated salt solutions or certified RH generation systems.
2.2 Ethylene Oxide (EO) Concentration
The accuracy and precision of the EO measurement system must be documented. Two primary techniques are used:
| Technology | Mechanism |
|---|---|
| Spectroscopy (IR) | Measures infrared light absorption by EO molecules. |
| Gas Chromatography (GC) | Separates EO via a column and quantifies concentration via a standard curve. |
For measurements taken outside the chamber, additional factors must be addressed:
- Pipe length and material compatibility (e.g., specific stainless steel grades).
- Leakage potential at connection points.
- Heat Tracing: Insulation of sampling lines to minimize condensation risk of EO or water vapor.
- Mechanical extraction (pumps or fans) from the chamber.
2.3 Temperature Monitoring
Consistency in instrumentation is required for both parametric and biological indicator release. Parametric release requires at least two independent monitoring locations.
3. Process Definition and Performance Qualification (PQ)
- Minimum Specifications: Established via microbial and physical PQ studies to ensure the required Sterility Assurance Level (SAL).
- Maximum Specifications: Established to ensure product safety, quality, and performance while minimizing EO residuals (per GB/T 16886.7).
- Cycles at lower limits of process parameters (humidity, temp, EO) to confirm sterility.
- Cycles at upper limits to evaluate product/packaging functionality and EO residual levels.