Stability Tests

What is Stability Testing?

Stability tests are analyses conducted to monitor the physical, chemical, microbiological, and sensory properties of a product under the temperature, humidity, light, and other environmental conditions to which it is exposed over time.

The objective is to assess whether the product remains effective, safe, and user-friendly throughout a specified shelf life.

Applications of Stability Testing

• Cosmetic Products (Creams, Shampoos, Make-up Products)
• Biocidal Products (Disinfectants, Antiseptics)
• Pharmaceuticals and medical products
• Dietary Supplements and Functional Foods
• Cleaning and Washing Agents

Types of Stability Tests

1. Long-Term Stability Test

• Conducted under actual storage conditions.
• Typically lasts 12 months or longer.
• Example conditions: 25 °C / 60% relative humidity

2. Accelerated Stability Testing

• To save time, more stringent environmental conditions are applied.
• Aims to predict long-term effects within a short timeframe.
• Example conditions: 40 °C / 75% relative humidity (6 months)

3. Stress Stability Tests

• Product stability is tested under extreme conditions (heat, UV light, freeze/thaw cycles).
• The product's resistance to potential degradation during transport and storage is assessed.

Parameters Evaluated in Stability Tests

Physical: Color, odor, consistency, precipitation, phase separation

Chemical: pH, active ingredient stability, oxidation

Microbiological: Contamination, preservative efficacy

Packaging Interaction: Substance migration from packaging, leakage, deformation

• pH Determination – European Pharmacopoeia 7.0, 01/2008:20203, page 24-25
• Determination of Solvents (Ethyl Alcohol, Methyl Alcohol, 1-Propanol, 2-Propanol (Isopropyl Alcohol)) – BS EN 14667, AOAC 983.13
• Density Determination
• Determination of Appearance, Count, Odor, and Color

The Importance of Stability Testing

• Shelf-Life Determination: Establishes the period for which the product can be used.
• Regulatory Compliance: Regulations for cosmetics and biocidal products mandate stability testing.
• Quality Assurance: Every product reaching the consumer must exhibit consistent quality.
• Marketing Confidence: Claims such as “2 years shelf life” are substantiated by scientific testing.
• Packaging Compatibility Control: Indicates whether interactions occur between the product and its packaging.

When is stability testing conducted?

• During the development of new products
• Upon formulation changes
• Upon packaging changes
• For regulatory notification and approval procedures