In the U.K, at University of Leeds.  Have a look at the Malvern website.

Dear Carlos Moreno Leon,

We have found in Brazil some laboratories able to carry out zeta potential measurements. They have asked, however, what voltage levels are considered high voltage in your case? You know, by standards any level above 1000 V is considered high voltage. What kind of sample is that one you have?

Hello Orsino,

We are using nicotinamide in dioxane and applying up to 7.5 kV. I was thinking in using the Zeta-Sizer workstation (Malvern equipment) but they already said that for a suspension of polarizable particles in a dielectric solvent I may obtain values very close to zero and not reliable. So, we are searching for alternatives.

Thanks,

For what reasons do you need to know the zeta potential of your system?

To verify whether or not the particles are subjected to electrophoresis