The emulsion of my sample has 0.08 polydispersity with an average size of 130 nm and only one peak (100 % intensity) both in DLS and MADLS. Nevertheless, I see two zeta potential populations.
Thank you in advance.
What instrument are you using? Can you share results?
DLS only measures size. So, it is possible to have two types of particles that are the same size but have different zeta potentials. There are also other possible causes depending on the instrument, the electrodes used, the salt concentration of the sample.
Suresh Ajmeera This is a little unusual. Have you verified the system with an appropriate mobility standard? Remember that zeta potential is inferred, not measured directly, from mobility (electrical or acoustic) measurements. Your system may have different chemistry on the surface of the particles from the manufacturing route. Is this an oil-in-water emulsion? How did you take the measurements?
@John Francis Miller and @Alan F Rawle
Sorry for the delayed response. Thank you both for your suggestions.
I use Malvern Zetasizer instrument. Indeed, I used a cuvette with electrodes to measure the Zeta potential. The salt concentration for this measurement is 1mM KCl sol.
I develop nanoparticles via water-in-oil emulsion. Below, you can find the results.
Hello Suresh Ajmeera
this is indeed a little unusual. The blue phase plot I would exclude, but the others appear of good quality. Can you measure size, then zeta, then size again, and all is consistent? It would be good if you could share the actual data file .zmes https://www.malvernpanalytical.com/en/learn/knowledge-center/insights/zs-xplorer-software-install-import-export