Preservative Efficacy Challenge Test

Preservative Efficacy Testing (PET) : USP 51, ISO 11930, and PCPC M-3

The proper balance between antimicrobial preservative efficacy and consumer safety is non-negotiable for cosmetics, personal care products, and pharmaceutical drugs. Our Preservative Efficacy Test (PET) (also known as Challenge Testing) is the definitive method used to assess a preservative system's ability to inhibit or kill invading microorganisms.

We offer testing following all major global standards:

• USP 51 (United States Pharmacopeia)

• ISO 11930 (International Organization for Standardization)

• PCPC M-3 (Personal Care Products Council Method 3)

We ensure your formulation meets the stringent safety and performance criteria defined by these industry-critical guidelines.

Our method simulates real-world contamination events using the five specified challenge microorganisms, helping manufacturers determine the true shelf-life and safety profile of their product.

1. Neutralization Validation: Before testing, we perform a crucial validation study to determine the precise method for neutralizing the preservative. This step is vital—improper neutralization can lead to an overestimation of efficacy, compromising your data and product safety.

2. Inoculation: Sub-samples of your product are inoculated with high concentrations of the five required strains:

   • Bacteria: Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 9027)

   • Yeast & Mold: Candida albicans (ATCC 10231), Aspergillus brasiliensis (ATCC 16404)

3. Evaluation & Reporting: Over a minimum of 28 days, the product is evaluated at specific time points (0, 7, 14, 28 days). We quantify the viable cells using a microbial enumeration test, reporting the log reduction for each microorganism. The preservative system's effectiveness is then judged against the established passing criteria defined by your chosen standard (USP 51, ISO 11930, or PCPC M-3).