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Dispersibility - Redispersion

Turbiscan: a single technology for complete dispersion analysis

TURBISCAN®  is the first patented technology to analyze destabilization mechanism in concentrated dispersed media and thus the only to offer accelerated aging tests on the actual unstressed product. In addition to creaming, sedimentation, aggregation analysis it can provide useful information on dispersibility of the particles in the media.
Dispersibility ratio can be easily calculated in order to, with a single number, quantify the affinity of dispersed media in the given solvent.

Multiple light scattering technology

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, 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, 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

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Data and key features

> Dispersibility

When it comes to real-life evaluation of the end-products, it is essential not to apply a mechanical stress to the sample. Since it brings a risk of altering the state of the dispersion. This is of high importance when measuring particle size of concentrated dispersions. With Turbiscan® measurements are always performed at rest, without any external stress. That way, the results are representative of the native dispersion state. 

> Dispersibility Ratio

The dispersibility is defined as a characteristic which qualifies the ability of a particle to be spatially well distributed in terms of size and concentration in a liquid after 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 presents the same stability as the freshly prepared one? 

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