With a team of experts and highly qualified facilities, thanks to more than 20 years of consolidated experience and laboratories equipped with the latest instrumentation, Mérieux NutriSciences | Pharma & HealthCare offers a complete range of highly complex analyses to ensure the quality of MSDs and biocide products.

Stability studies are essential to ensure that a MSD or biocide product maintains its chemical, physical, technical characteristics and efficacy during the declared shelf life. These studies are not only a regulatory requirement, but also a key component to ensure consumer safety and product efficacy under the intended conditions of use.

Types of stability studies

Stability studies can be classified into three main categories:

Accelerated stability:

• It is conducted under extreme conditions to simulate the deterioration of the product in a
  short time. Typically, a temperature of 54 °C is used for a period of 14 days, in accordance
  with CIPAC Guideline 46.4 .
• This study allows to attribute a minimum shelf-life of at least two years under normal
  environmental conditions.

Table 6. Accelerated storage test conditions for heat-sensitive active substances.
TEMPERATURE (± 2 °C)	TIME (weeks)
54	2
50	4
45	6
40	8
35	12
30	18

Long-term stability:

• It is carried out under conditions that reflect the real environment in which the product will be stored, monitoring specific parameters for the entire declared shelf life.
• It includes tests to verify interactions with the packaging, since inappropriate materials could affect the stability of the product.
• The tests are performed according to the ICH guideline and GIFAL guideline

Design a stability study. According to the BPR guideline, the titre of the active substance, the physical-chemical parameters and the relevant technical properties must be monitored at the beginning and end of the study. The design of the study depends on the product and its characteristics. In long-term stability, the biocide must be stored in the sale packaging and during the study the packaging and the reactions with the product must also be evaluated.

Low temperature stability:

• Required for liquid biocides, it verifies that the product does not undergo alterations at temperatures ≤0 °C. It is an important requirement for products intended for cold climates or specific storage situations.
• The tests are performed according to CIPAC Method MT 39.3

Parameters
During stability studies, several parameters are monitored:

• Content of the active substance.
• Physical-chemical properties such as density, pH, acidity or alkalinity.
• Physical appearance of the product (color, sedimentation, formation of precipitates).
• Integrity of the packaging, which must keep the product protected from external contamination and chemical reactions.

Tests specific to the formulation type (e.g. spray pattern for triggers)

Regulatory implications
Regulatory authorities require robust stability tests to ensure that biocides on the market are safe and effective. Stability studies influence:

• The shelf life stated on the label.
• Transport and storage conditions.
• Recall procedures for non-compliant batches.

Stability studies are a cornerstone for the development and registration of biocidal products, ensuring their quality, safety and compliance throughout the entire life of the product.