Stability Tests on Cosmetic Products: Determination of Quality and Durability
A Cosmetic Product must be able to maintain the appearance, smell, consistency and effectiveness of the first day throughout its shelf life. However, formulations are sensitive to environmental factors such as temperature fluctuations, exposure to light, fluctuations in humidity and interactions with the packaging. Phase separation, color changes, odor changes or the loss of the effectiveness of the preservation system endanger both the commercial value of the product and consumer safety. Therefore, the Cosmetic Stability Test is an indispensable part of the product development process and the approval dossier.
The basic guideline, which is used internationally as a reference for stability assessment, is ISO/TR 18811. This technical report provides a comprehensive framework for the design, implementation and evaluation of stability tests for cosmetic products. In addition, the Product Information File (PIF) created under the EU Cosmetics Regulation (EC) No. 1223/2009 and the Safety Assessment Report (SAR) require stability data.
Why are stability tests required?
Cosmetic stability tests are performed to demonstrate that the product meets acceptable quality criteria during its set shelf life. These exams provide answers to the following questions:
- Physical stability: Does the product lead to phase separation, precipitation, viscosity changes or crystallization over time?
- Chemical stability: Drugs, preservatives or color pigments disintegrate? Does the pH change?
- Microbiological Stability: Does the preservation system maintain its effectiveness over the entire shelf life?
- Compatibility with the packaging: Are there any reactions or migration between the product and the packaging material?
Answering these questions with scientific methods ensures both the safe marketing of the product and the avoidance of possible recall risks.
Types of Stability Tests and Application Conditions
In line with industry applications, three basic types of stability tests are used for cosmetic products:
1. Long-term stability test (real-time)
Detects the behavior of the product over time under normal storage conditions (usually 25 ± 2 °C, 60 ± 5% R.F.). The test duration is usually 12 to 36 months and serves as a reference for determining the final shelf life of the product.
2. Accelerated Stability Test
These are tests performed under high temperature conditions (usually 40 ± 2 °C, 75 ± 5% relative humidity). The aim is to quickly identify potential weaknesses of the formulation without having to wait for the results of long-term tests. The results of the accelerated tests should be evaluated along with the long-term data; They alone are not enough to determine the shelf life.
3. Cycle test
Simulates the temperature fluctuations that the product may be exposed to during transport and storage. Typically, temperature cycles in the range of -5 °C to +45 °C are carried out. This is particularly important to assess the risk of phase separation in emulsion-based products.
Comparison of stability test methods
The following table summarizes the stability test methods used in cosmetic products and their essential characteristics:
| Test type | Conditions | Duration | Purpose | Evaluated parameters |
|---|---|---|---|---|
| Long-term | 25 ± 2 °C / 60 ± 5% r. f. | 12-36 Months | Determination of the final shelf life | Physical, chemical and microbiological stability |
| Accelerated | 40 ± 2 °C / 75 ± 5% r. f. | 3-6 Months | Quick detection of potential vulnerabilities | Degradation products, color changes, pH shift |
| Cycle (cycle) | Cycles between -5 °C and +45 °C | 1-3 Months | Simulation of fluctuations during transport and storage | Phase separation, viscosity change, packaging integrity |
| Light stability | I Q1B compliant light exposure | 2-4 Weeks | Evaluation of light-related decomposition | Color change, drug loss, oxidation |
Packaging compatibility: an aspect that should not be neglected
The stability test should include not only the formulation itself, but also the interaction of the product with the packaging. Various types of packaging, such as glass, plastic, metal or airtight pumps, can cause the product to behave differently in terms of moisture loss, oxidation, translucency and chemical migration.
ISO/TR 18811 recommends carrying out stability tests in the final trade packaging (or equivalent packaging). Phenomena such as migration from the packaging (e.g. the transition from plasticizers to the product) or adsorption (attaching the active ingredient to the packaging surface) can directly impair the safety and effectiveness of the product.
GLP compliant stability tests for cosmetics with nano-test
The durability and quality assurance of your cosmetic products are based on correctly designed and carefully carried out stability studies. Nano-Test is a reliable solution partner for the cosmetics industry with its comprehensive stability testing services, which are based on the relevant standards.
Description of Nano-Test Services
Nano-Test offers Stability Tests (Stability Test) for cosmetic products.
Our service portfolio:
- Long-term stability: 12-36-month monitoring, regular sampling and analysis under conditions of 25°C/60% r. f.
- Accelerated stability test: 3-6-month examinations under conditions of 40°C and 75% R. F. For early detection of vulnerabilities in the recipe.
- Cycle tests: Temperature cycles simulating transport and storage conditions.
- Light stability: I Q1B compliant light resistance testing.
- Compatibility with the packaging: Evaluation of the interactions between product and packaging (migration, adsorption).
- Physical-chemical analyzes: pH value, viscosity, color (L*a*b*), phase separation, drug determination and microbiological quality.
Contact us. info@nano-test.de