Testing Preservative Effectiveness in Formulations
Asked by: jn_andy
On: August 07, 2018
Product Type:
Cosmetics
Question
How can I test the effectiveness of preservatives in a finished formula? What methods or simple tools can I use for self-testing, and if self-testing is not feasible, where and how should I send the product for professional testing, such as a Challenge Test?
Answer
Subject: Testing the effectiveness of preservatives in a formula
Regarding your questions on testing the effectiveness of preservatives in a finished formula:
Methods for self-testing or simple tools:
- Culturing microorganisms requires specialized equipment and experience and is strongly not recommended for self-testing.
- A simple method is accelerated testing by incubating the product in an oven (like an incubator oven) at 40°C for several weeks. This temperature encourages microbial growth. If the preservative is ineffective or if there was contamination during production, signs of microbial growth will become evident.
- However, this method primarily tests for contamination during the production process and the general effectiveness against ambient microbes. It does not cover scenarios where microbes are introduced by the user (e.g., dipping fingers into the product).
Where and how to send for testing:
- For more comprehensive testing, especially to assess the preservative's ability to handle microbial contamination during use (like a challenge test), it is necessary to send the product to a specialized laboratory.
- The staff reply implies that professional testing is required for this, but does not specify particular laboratories. You would typically look for laboratories that perform microbial testing for cosmetic or related products.
