OECD TG 113 is the standard “Screening Test for Thermal Stability and Stability in Air, ” i.e., the screening test for thermal stability and stability in air, which is listed in Section 1 (Physicochemical Properties) of the OECD Test Guidelines for the Testing of Chemicals.
The purpose of the test is to preliminarily evaluate a substance’s thermal stability when heated and its oxidative stability upon contact with air. OECD TG 113 is a screening test; rather than determining precise thermodynamic or kinetic parameters, it aims to quickly and reliably determine whether the substance decomposes in a hazardous manner.
Thermal stability is a measure of the extent to which a substance retains its chemical structure when heated. Stability in air, on the other hand, describes the substance’s resistance to oxidation or other air-related reactions in the presence of oxygen. This test allows for the simultaneous evaluation of these two properties.
OECD TG 113 does not prescribe a specific method but allows the use of appropriate and validated thermal analysis methods. Common methods include:
Differential Scanning Calorimetry (DSC):
- The specimen is heated according to a controlled temperature program, and the change in heat flux is measured
- Exothermic and endothermic transitions, the decomposition onset temperature, and the peak temperature are determined
- To determine oxidative stability, the sample is analyzed in air or an oxygen atmosphere; to determine thermal stability, it is analyzed in an inert atmosphere (nitrogen, argon), and the results are compared.
Thermogravimetric Analysis (TGA):
- The change in the mass of the sample is measured as a function of temperature
- The initial temperature of mass loss, the decomposition stages, and the residual amount are determined
- Comparing the measurements taken in air and in an inert atmosphere allows for an assessment of oxidative decomposition
Differential Thermal Analysis (DTA):
- The temperature difference between the sample and the reference material is measured
- Used to detect exothermic and endothermic processes
- Provides information similar to that of the DSC; may be preferred depending on the device's features
Simultaneous DSC/TGA (STA):
- Simultaneous Measurement of Thermal and Gravimetric Changes in the Same Sample
- Enables the interpretation of decomposition processes based on changes in heat and mass
Tests with a closed or open crucible:
- Sealed crucibles for evaluating pressure buildup and volatile products
- Open crucibles for evaluating the effect of oxygen access
The basic parameters reported in the study are:
Initial decomposition temperature (°C) and peak temperature
Oxidation onset temperature (measured in air)
Mass loss (%) and temperature at the onset of mass loss; Identification of exothermic/endothermic processes; Atmosphere used (air, oxygen, nitrogen, argon); Heating rate, sample quantity, and container type; Data on measurement uncertainty and repeatability
Why is this being done?
OECD TG 113 is being conducted for the following scientific and regulatory purposes:
Determination of thermal stability: Determining whether the substance decomposes at storage, transport, and processing temperatures
Assessment of oxidative stability: Determination of the substance's tendency to oxidize or react spontaneously upon contact with air
Hazard Identification: Early detection of thermally unstable substances or those that react with air (e.g., self-heating substances, oxidizing agents)
Classification and Labeling: Assessment of thermal stability and the potential for spontaneous reactions in the context of transport regulations (UN/ADR) and chemical classification (CLP/GHS)
Establishing safe storage and transport conditions: Providing information on the maximum safe processing and storage temperatures
Process Safety: Preliminary Assessment of Thermal Risks in Chemical Processes
Input for Additional Tests: Data on thermal stability influence the design and conditions of other physicochemical and toxicological tests
- Quality Control: Monitoring the consistency of the material during the manufacturing and storage processes
- "Weight-of-Evidence" Approach: Contribution to a comprehensive assessment of the substance in conjunction with other physicochemical data and safety assessments
OECD TG 113 does not, in and of itself, constitute a toxicity or comprehensive hazard assessment. It provides physicochemical information as part of a screening process; the results should be interpreted in conjunction with other thermal analysis data, reactivity tests, and safety assessments.
As part of our nano-testing services, we conduct thermal stability and air stability screenings in accordance with OECD TG 113 with scientific rigor, utilizing our accredited laboratory infrastructure and quality management system. Our scope of services includes the following:
Method Selection and Validation
- Selection of the appropriate method (DSC, TGA, DTA, STA) based on the properties of the test substance and regulatory requirements
Selection of atmosphere: inert atmosphere (nitrogen/argon) for thermal stability; air/oxygen for oxidative stability
Validation of the selected method and verification using appropriate reference substances (e.g., indium, zinc, tin)
Calibration of Temperature and Heat Flux; Evaluation and Reporting of Measurement Uncertainty
Documentation of method-specific limitations and conditions of use
For information on the selection of methods and atmospheres, sample acceptance criteria, the test plan, and reporting procedures for your thermal stability and air stability tests in accordance with OECD TG 113, please feel free to contact Nano-Test.