OECD Method 102 determines the temperature at which a substance changes from a solid to a liquid state, an essential physicochemical parameter for the characterization, classification, and regulation of chemical substances. Widely used in safety studies and the preparation of Safety Data Sheets (SDS), this method is standardized internationally through OECD guidelines . In this article, we analyze in detail the content of OECD Guideline 102, the authorized test methods, their scientific and regulatory significance, and their practical implementation in the laboratory. We will also examine the sectors for which this measurement is crucial, before presenting the support offered by YesWeLab for conducting these tests within a regulated framework.
Table of Contents
What is OECD Method 102?
A guideline for standardizing melting temperature measurements
OECD Method 102 is one of the guidelines published by the Organisation for Economic Co-operation and Development (OECD) as part of the programme for harmonizing testing for chemicals. It describes several methods for determining the melting point or melting range of a substance, that is, the temperature at which a substance changes from a solid to a liquid phase under normal atmospheric pressure.
This melting point is a fundamental physical property, directly linked to the molecular structure and purity of a compound. It is also a regulatory parameter required in many registration dossiers (REACH, SDS, CLP classification, etc.).
OECD Guideline 102 provides a harmonized framework to ensure comparability, reliability and international recognition of data from laboratories.
Objectives of the method and regulatory scope
The main objective of OECD Method 102 is to accurately measure the temperature (or temperature range) at which the solid/liquid phase transition of a substance occurs. This information allows:
- to identify a substance in a unique way,
- to detect the presence of impurities (which lower or widen the melting range),
- to classify substances according to their thermal behavior,
- to provide mandatory data within the framework of SDS and REACH dossiers,
- to guide the conditions of storage, transport or industrial processing.
The results of these tests can be used to demonstrate compliance with European regulations (Regulation EC No. 1907/2006 known as REACH, Regulation CLP No. 1272/2008), American OCSPP standards, or United Nations requirements relating to the transport of dangerous goods.
A method suitable for different types of substances
OECD Guideline 102 recommends the use of several methods depending on the physical nature of the substance being tested. The choice depends in particular on:
- of the physical state of the substance (crystalline, amorphous, pasty),
- its ability to be pulverized or molded,
- of its apparent purity or its composition (pure substance vs complex mixture).
Thus, crystalline solids can be analyzed using the capillary method, while polymers, waxes, or pastes will require alternative techniques (DSC, pour point, etc.). This flexibility allows the OECD 102 method to be applied to a wide variety of substances, ranging from technical chemicals to pharmaceutical excipients, including food additives and cosmetic ingredients.
What is the meaning of OECD?
The Organisation for Economic Co-operation and Development
The OECD , or Organisation for Economic Co-operation and Development, is an international organization founded in 1961 and currently comprising 38 member countries. Its main objective is to promote policies that improve economic and social well-being worldwide. It intervenes in numerous areas, such as the economy, education, taxation, the environment, and health, but it also plays a central role in the regulation of chemicals.
In the field of chemical substances, the OECD develops Test Guidelines that are used by laboratories worldwide. These guidelines define standardized analytical methods for evaluating the physicochemical, toxicological, and ecotoxicological properties of substances. These protocols are scientifically validated, internationally recognized, and regularly updated to reflect technological advancements.
The role of the OECD in the assessment of chemicals
In the field of chemical safety, the OECD has established the Joint Chemical Testing Programme, which aims to facilitate data sharing among member countries and avoid duplication of animal testing. This program is based on the principle of Mutual Acceptance of Data (MAD), which ensures that the results of a study conducted according to an OECD guideline and under Good Laboratory Practices (GLP) are accepted by all regulatory authorities in the countries adhering to the system.
Guidelines such as OECD Method 102 are therefore part of a body of more than 150 methods covering:
- the physicochemical properties (density, solubility, flash point, etc.),
- toxicity to human health (acute toxicity, skin irritation, mutagenicity, etc.),
- ecotoxicity (fish, algae, microorganisms, etc.) ,
- behavior in the environment (biodegradability, adsorption, etc.).
Importance of OECD guidelines for laboratories and industry
The use of OECD guidelines is crucial to ensuring the scientific validity and regulatory recognition of experimental data. For laboratories, following these methods means:
- reliable and reproducible results ,
- to ensure the comparability of data between laboratories,
- to obtain international recognition of the trials,
- to meet the requirements of regulations such as REACH or CLP.
For manufacturers, this allows for the centralization of regulatory data required for the marketing of chemical substances in several countries. Indeed, a single study conducted according to OECD 102 in an accredited laboratory can be used in a REACH registration dossier in Europe , in an EPA dossier in the United States , or even in a safety report for the transport of dangerous goods according to the UN .
The OECD therefore acts as a key player in international regulatory harmonization , providing laboratories and industries with a robust, recognized and shared scientific framework.
Are you looking for an analysis?
Methods described by OECD 102 for measuring the melting point
OECD Guideline 102 describes several experimental methods for measuring the melting point or range of a substance. The choice of method depends primarily on the physical state of the substance being tested (crystalline solid, paste, waxy, polymer), its ability to be ground or molded, and the required accuracy. The common objective is to identify the temperature at which a substance transitions from a solid to a liquid state, under atmospheric pressure, with maximum reliability.
Traditional methods
Traditional methods rely on the direct observation of the substance's change of state in a device heated in a controlled manner. They are simple to implement, but require some expertise to correctly interpret the results.
Capillary tube in liquid bath
This is the oldest and most widely used method for crystalline solids. It involves placing a finely powdered sample in a small glass tube sealed at one end (capillary tube), then heating this tube in a liquid bath (often silicone oil) at a controlled rate. The observer records the temperature at which the substance begins to melt, and then the temperature at which it is completely melted.
This method makes it possible to obtain a melting range (two temperatures) useful for evaluating the purity of a substance: a significant difference between the two values generally indicates the presence of impurities.
Capillary tube in metal block
This variant uses a metal oven instead of a liquid bath, with an optical device or magnifying glass to observe the capillary tube. Less messy and easier to automate, it is often used in modern laboratories for serial measurements.
Kofler heated bench
The Kofler hot stage is a device consisting of a metal plate heated by a temperature gradient. The sample is placed on the plate, and the area where melting begins and ends is marked. This method is fast and ideal for comparing several samples simultaneously, but it is less precise than other techniques.
Fusion microscope
This technique combines gradual heating and microscopic observation. It allows for real-time observation of changes in crystal morphology during melting. It is used for heat-sensitive substances, products available in small quantities, or heterogeneous materials.
Advanced instrumental methods
Instrumental methods allow for automated, more precise and reproducible measurement of the melting point. They are particularly suited to complex or heat-sensitive substances.
Differential thermal analysis (DTA)
The DTA measures the temperature difference between a sample and a reference material subjected to the same heating program. When a phase transition occurs in the sample (melting, crystallization), a temperature difference is recorded as a peak on a curve. This method provides an accurate melting temperature but does not provide an enthalpy value.
Differential scanning calorimetry (DSC)
Differential scanning calorimetry (DSC) is a reference method in the laboratory. It measures the energy difference required to maintain the same temperature between the sample and a reference. During melting, the resulting curve shows a peak corresponding to heat absorption. This allows us to determine:
- the melting point ,
- the enthalpy of fusion (ΔH),
- the thermal purity of the compound.
DSC is widely used for polymers, waxes, complex substances or in stability studies.
Special cases
Some substances do not have a clear melting point, but rather exhibit a gradual or pasty behavior when heated. This is the case for complex mixtures, resins, amorphous products, or thermoplastic polymers.
Pouring point
The pour point is the temperature at which a substance begins to flow freely under the influence of heat. It is used for waxes, greases, and certain polymers. It can be measured with specific devices (heated viscometers, flow cups).
Freezing point
Conversely, the freezing point is the temperature at which a liquid substance solidifies under normal conditions. Although less frequently used than the melting point in OECD 102, it can be relevant for certain molten mixtures or supersaturated solutions.
OECD Guideline 102 therefore offers a comprehensive range of methods to suit all types of substances, from pure solids to technical products. The choice of method directly determines the reliability of the results and their regulatory validity .
Application of the OECD 102 test in the laboratory
The OECD 102 test is not merely a theoretical scientific protocol; it is widely used in analytical laboratories to meet regulatory, industrial, and safety requirements. Implementing this test requires specific equipment, precise technical expertise, and methodological rigor governed by international standards. The results produced must be usable within demanding legal frameworks, including REACH, CLP, and regulations governing the transport of dangerous goods.
Practical implementation conditions: GLP vs. non-GLP
OECD 102 tests can be performed with or without Good Laboratory Practices (GLP), depending on the intended use of the results:
- Testing under GLP conditions : required for REACH regulatory dossiers, CLP notifications, marketing authorization applications, or biocidal and plant protection product dossiers. These tests follow a strict protocol overseen by a quality assurance unit, with data archiving, full traceability, and the preparation of a final report compliant with IUCLID.
- Non-GLP testing : suitable for internal studies, formulation development, validation of industrial batches, or exploratory needs. These tests can provide a reliable indication of the melting point without requiring full traceability.
In both cases, the laboratory must use a validated method in accordance with OECD guideline 102, and be equipped with calibrated instruments to ensure the reproducibility of results.
Accreditations and regulatory recognition
For the test results to be legally admissible, particularly in the case of REACH registration or CLP classification, they must be produced in an accredited or recognized laboratory. Two levels of recognition are essential:
- ISO 17025 accreditation : an international standard that guarantees the laboratory's technical competence, the reliability of the methods used, and the traceability of results. It is an essential requirement for many sectors (chemicals, cosmetics, environment).
- COFRAC recognition (in France) : guarantees compliance with European and national requirements. COFRAC accreditation demonstrates that the methods used are audited, validated, and regularly monitored.
Most of YesWeLab's partner laboratories have these accreditations, ensuring their clients current regulatory requirements
Relevant standards and regulations
The OECD 102 test is recognized by several national and international regulatory frameworks. Depending on the use of the tested substance (transport, placing on the market, safety, environment), the results of this test may be required in the following documents:
- REACH (Regulation EC No. 1907/2006) : registration of chemical substances with ECHA, requiring a complete dossier including physico-chemical properties.
- CLP (Regulation (EC) No 1272/2008) : classification, labelling and packaging of hazardous substances. The melting point is used to determine the physical class of certain products.
- OCSPP (United States) : American equivalent of OECD guidelines, used by the EPA.
- Transport of dangerous goods (UN) : melting points are used to classify certain materials according to their thermal risk (explosives, flammable liquids, self-reactive solids).
- Biocidal and phytosanitary regulations : marketing authorizations require precise physico-chemical characterization of each active substance or formulation.
Therefore, carrying out an OECD 102 test in a qualified laboratory ensures the compliance of your products with all of these regulations.
Examples of laboratory analyses: focus on the melting point in a regulatory context
Measuring the melting point or melting range is an essential step in the analysis of chemical substances, whether pure, formulated, or derived from complex matrices. Beyond physicochemical characterization, this data is often indispensable for meeting safety, compliance, or product performance requirements. In this section, we present concrete examples of analyses performed in the laboratory using OECD 102 methodology, in relation to common industrial and regulatory needs.
Pure substances and complex mixtures: two distinct approaches
Pure substances
Pure substances (organic compounds, minerals, solvents, acids, bases, etc.) are generally analyzed using conventional methods (capillary tube, DSC) to determine their exact melting point. A sharp, narrow, and reproducible melting temperature is often indicative of high chemical purity , which is crucial for pharmaceutical, cosmetic, or synthetic applications.
The analysis allows us, in particular, to:
- Identify a compound by comparing it to known references.
- Control the quality of a batch by detecting any impurities.
- Validate thermal stability before transport or processing.
complex mixtures
For mixtures (waxes, polymers, resins, technical formulations), melting point analysis proves more complex. These products often do not have a single melting point, but rather a wide temperature range due to the diversity of their constituents.
In these cases, instrumental methods such as DSC or pour point are preferred. They allow us to:
- Identify several thermal transitions (partial melting, softening, crystallization).
- Define a functional operating temperature (processing or forming temperature).
- Compare the thermal performance between formulations.
Integration of melting point into safety data sheets (SDS)
The safety data sheet (SDS) is a mandatory regulatory document for any substance or mixture placed on the European market (according to REACH and CLP). The melting point is listed in section 9 (physical and chemical properties) of the SDS.
It must be:
- measured experimentally , unless reliable data from the literature are available,
- reproducible,
- referenced with the method used (for example: OECD 102 – DSC – GLP method),
- consistent with other physico-chemical properties (density, boiling point, vapor pressure, etc.).
In the case of a new substance or specific formulation (custom cosmetic, innovative food supplement, technical chemical product), experimental measurement in the laboratory becomes essential to provide the SDS with up-to-date, accurate and legally valid data.
Other complementary physico-chemical tests
Melting point analysis is part of a broader set of tests required to establish the physicochemical profile of a substance. Tests frequently associated with OECD 102 include:
- OECD 101 – UV-VIS absorption spectra : useful for determining the light absorption of a substance.
- OECD 103 – Boiling point / Boiling range : complementary to the melting point to establish the thermal volatility range.
- Solubility, density or thermal stability tests , all recognized by the OECD.
The combination of these analyses makes it possible to build a complete profile of the substance studied, guaranteeing both its traceability , its regulatory compliance , and its control in formulation or process .
For which sectors is measuring the melting point essential?
The measurement of the melting point or melting range, while seemingly a purely physicochemical parameter, is in fact a strategic parameter in many industrial sectors . This data directly influences manufacturing, storage, and safety conditions, as well as product regulatory compliance. Each sector has specific requirements in terms of quality control, regulations, and functional performance, making analysis according to OECD 102 essential at several levels.
Food industry
In the food industry, the melting point is used to assess:
- the thermal stability of the ingredients (additives, flavorings, texturizing agents),
- the behavior of fats (hydrogenated oils, vegetable butters, waxes),
- the functional properties of powders or coatings (heat resistance, controlled release).
For example, a wax-based coating must melt at a specific temperature to release an aroma or active ingredient under precise conditions (in hot water, in the mouth, etc.). Similarly, the melting point of certain additives helps ensure the stability of finished products during transport or storage.
Nutraceuticals and food supplements
The nutraceutical sector imposes strict requirements regarding the traceability and quality of ingredients. The melting point allows us to:
- to control the purity of active substances (vitamins, organic acids, plant extracts),
- validate the manufacturing conditions (thermal safety of the capsules, stability of the powders),
- check for the absence of alteration during industrial processes (compression, granulation, encapsulation).
For temperature-sensitive substances, such as certain vitamins or amino acids, reliable thermal analysis ensures the performance of the finished product and its compliance with nutritional claims.
Cosmetic
In cosmetic products, the texture, stability, and efficacy of formulations often depend on the thermal behavior of their components. Melting point analysis allows us to:
- to formulate waxes, butters or balms with the correct consistency at room temperature,
- to control the stability of emulsions (creams, lotions),
- to assess heat stability during storage or transport.
The oily or thickening phases must melt or remain stable within specific temperature ranges. For example, a lipstick should not melt at 30°C, but should spread perfectly upon contact with the lips.
Materials, packaging and polymers
Knowledge of the melting point is crucial for thermoplastic or thermosetting materials used in:
- food packaging ( plastic films, coatings, caps),
- technical materials ( resins, composites, bio-based polymers),
- hot melt adhesives .
The OECD 102 method makes it possible to identify the thermal transition range , essential for defining the conditions of industrial transformation (extrusion, molding, thermoforming) or potential migration in packaging (in accordance with EC Regulation No. 1935/2004 and FDA standards).
Animal health
In animal health, additives and excipients used in medicated feeds, boluses, or nutritional supplements must be stable, safe, and functional . The melting point is one indicator of this.
- the quality of the raw materials (oils, waxes, coating agents),
- controlled release of active ingredients into the digestive system,
- of the thermal resistance of formulations under transport or manufacturing conditions.
These analyses are particularly important for products intended for livestock, which are exposed to varying environments.
Environment and industrial safety
Finally, in sectors related to the environment, industrial chemistry, or waste management, knowledge of the melting point allows for:
- to classify substances according to their thermal hazard (flammability, self-reactivity),
- to plan their disposal or recycling according to appropriate procedures,
- to guarantee the safety of processes involving temperature increases (heating, incineration).
Some substances can become unstable or reactive as soon as their melting point is reached. It is therefore essential to know this in order to implement safety protocols.
In each of these sectors, melting point analysis according to OECD 102 plays a key role in quality control, regulatory compliance, product safety and industrial performance.
Why use YesWeLab to perform an OECD 102 test?
Performing an OECD 102 test requires much more than simply having access to a thermal measurement device. It involves technical expertise , a thorough understanding of regulations , the ability to adapt to the matrices being analyzed , and rigorous data and report management . This is precisely what YesWeLab offers its industrial clients through its platform and network of partner laboratories.
A network of 200 accredited and specialized laboratories
YesWeLab relies on a network of over 200 laboratories in France and Europe, covering all areas of chemical, physical, biological, and regulatory analysis. All OECD tests offered are performed by laboratories:
- accredited to ISO 17025 to guarantee technical competence and traceability of results,
- qualified to work under Good Laboratory Practices (GLP) when required,
- equipped with the latest thermal analysis technologies: DSC , DTA , fusion microscopy , Kofler benches , etc.
This allows each test to be adapted to the specific requirements of the substance being studied, whether it is pure, formulated, paste-like, heat-sensitive or polymeric.
A digital platform to simplify the management of analyses
One of YesWeLab's major strengths lies in its centralized digital platform , designed to facilitate and accelerate the management of analytical projects. Thanks to this solution:
- Manufacturers can search for and order their analyses in just a few clicks, with more than 10,000 services available.
- The sending of samples is guided and secure , with integrated traceability.
- The results are accessible online as soon as they are validated, with the option to automatically generate technical or regulatory reports.
- Each client benefits from personalized support from an analytical expert.
This model helps to reduce execution times , limit processing errors, and ensure smooth monitoring from the beginning to the end of the project.
Multi-sectoral and regulatory support
YesWeLab does more than simply transmit test results. The company is committed to interpreting, contextualizing, and ensuring the safe use of the generated data . It supports its clients in a variety of sectors, with a thorough understanding of applicable regulations.
- Chemical industry : integration of OECD 102 results into REACH dossiers or CLP declarations.
- Cosmetics and food supplements : compliance with safety and labeling requirements.
- Food processing : evaluation of the thermal stability of ingredients or additives.
- Materials and polymers : compatibility with 1935/2004 standards, FDA or migration tests.
- Environment and safety : classification of substances according to physical hazard criteria (critical melting point, reaction thresholds).
Each project is treated with a tailor-made , linked to the regulatory, industrial or R&D objective.
Reports that are compliant and immediately usable
YesWeLab provides its clients with comprehensive analytical reports that can be used for:
- integration into an IUCLID dossier (in the event of a REACH application),
- updating a safety data sheet (SDS) ,
- a regulatory declaration to a competent authority,
- a technical justification within the framework of a quality audit or a certification procedure.
Each report specifies:
- the method used (e.g., OECD 102 – DSC – GLP mode),
- the raw and interpreted results (melting point, range, enthalpy, etc.),
- experimental conditions ( heating speed, calibration, sample purity),
- normative and regulatory references .
This level of rigor guarantees full admissibility of data , whether in Europe, the United States, or in countries using OECD guidelines.
Using YesWeLab for your OECD 102 tests means benefiting from an expert, fast, reliable and regulatory-compliant partner , capable of transforming a technical requirement into a strategic result for your company.
