Seven test methods for stable formulations.

Rheological investigations – that is, measurements of flow and deformation behaviour – comprise the determination of the elastic and viscous components of formulations. Measurements on the rotational viscometer can be carried out in rotational or oscillatory mode.

In particular, the influence of the following factors on the rheological properties of the overall system can be evaluated:

Determining the size distribution of the inner phase in disperse systems such as creams and milks is an essential element in the development of new cosmetics. Green River Polymers carries out the corresponding measurements as a matter of routine.

The release of actives from topical preparations within a defined period is an important parameter for assessing the quality of a cosmetic product. Since every formulation has its own release characteristics, in vitro release studies allow conclusions to be drawn about the condition and properties of the cosmetic.

Green River Polymers carries out active release studies on both liquid and semi-solid cosmetic formulations. The Franz diffusion cell system serves as the in vitro release apparatus. Depending on the type of formulation and on the active to be evaluated, various synthetic or semi-synthetic membranes are used.

After an initial lag time has elapsed, release is determined under “quasi-stationary” conditions – the quantity of active released is then proportional to the square root of time. The values obtained during this matrix-controlled phase feed into all further calculations as product-specific parameters.

In the climate chambers we use, temperature and relative humidity are monitored and recorded electronically 24 hours a day, 365 days a year. In the event of a power failure, an in-house emergency generator is available.