Dispersibility - Redispersion

> Dispersibility

SMLS is the only technique of stability analysis to offer the advantage of working in concentrated media: It is well adapted for working without dilution and without stress over a wide particle size range: 10 nm - 1 mm at high concentrations (up to 95% v:v).

The emitted light only partially passes through the tube, most are scattered by the particles in the sample. TURBISCAN® detects the intensity of both Transmitted and Backscattered light over the whole tube height. These intensities allow direct monitoring of local physical heterogeneities with a vertical resolution down to 20µm. Thus, the nascent destabilization phenomenon (sedimentation or creaming layers, aggregates, agglomerates or coalescence) can be detected and monitored over time at different intervals.

TURBISCAN® technology is the perfect solution for a complete analysis and understanding of real-life destabilization phenomena. Indeed, the stability of colloidal dispersions depends on many parameters (size, concentration, charges, rheology…). Techniques such as zeta potential, particle size, conductivity or rheology provide useful but limited information to one parameter and do not characterize the overall stability

> Dispersibility Ratio

The dispersibility is defined as a characteristic that qualifies the ability of a particle to be spatially well distributed in terms of size and concentration in a liquid after a controlled dispersion process. The goal is to reach a state as close as possible to the "primary particle size" or required size. The Turbiscan® provides a simple calculation that compares initial particle size with the theoretical value allowing to quantify the dispersibility.

> Redispersion testing

In many industrial applications: coatings and paints, injectables drugs, dairy drinks, destabilization is unavoidable and redispersion will be required. The main concern is that the redispersion technique (stirring, shaking, etc.) will not be energetic enough to render the suspension back to its initial, homogeneous state. When this is the case the sample is then unusable and must be discarded. The prediction of this effect and its quantification is critical and a fast, quantitative method is required to answer commonly asked questions

-     Would the manual shaking be enough to well re-disperse the formulation? 
-     How long should it be shaken for? 
-     What method to use: stirring, shaking, mixing, ultrasound bath? 

> Redispered formulation stability

Once the sample redispersion is achieved, the formulation is renewed and parameters like size, stability, and re-redispersion can be studied again and again. It is of great interest to understand if the formulation can retrieve its original state and properties. How many of these “life cycles” the formulation can support before destabilization is irreversible (and upon what storage conditions)? Does the redispersed formulation present the same stability as the freshly prepared one? 

Working with Turbiscan allows to characterize these properties on the same sample set as the measurement is done without any stress to the sample.