I am intending to do particle size, polydispersity index and zeta potential analysis of my SEDDS formulations. There is an option for dispersant. As i have used one oil and two surfactants in each formulation these all together act as media. And the ratio of oil to ssurfactant is also different in each formula. So there is no constant liquid material which is present in high amount in each formulation. What should be my "dispersant" here? Or is there any other process through which zetasizer can analyze without this information?
Hi Snigdha,
The Zetasizer analysis needs information about the dispersant, or continuous phase of your sample as the RI and viscosity are used in the calculation of particle size and the dielectric constant is used calculation of zeta potential.
The software does allow for custom dispersants to be defined and saved for future use, and calculators for composite dispersants, although if you are looking for a quick comparison between samples, choosing the closest dispersant from the list will give you data that you can compare.
For size (intensity based) and zeta measurement you only need the RI of the continuous phase (and to only 2 decimal places typically). This can easily be measured with an Abbe refractometer. Even high concentrations of surfactant will not affect the RI significantly. See:
Uses of an Abbe refractometer http://tinyurl.com/lbp4szy
If the refractive index of oil or surfactact is available, then it can be used as dispersant. Good luck.
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