I would like to know your experience on the potential impact of the extent of dilution of a micelle formulation on the variability of Zetasizer parameters (surface charge, PDI and size).
Thanks
Miguel Pereira-Silva Thank you for your question. With what medium do you intend diluting your starting material? A concentration ladder is recommended in the international standards (ISO & ASTM) in order to ensure that the concentration is correct to avoid:
- Low signal/noise: concentration too low, particles very small, low optical contrast (relative refractive index)
- Too concentrated: particle-particle interactions; hindered mobility; possibility of multiple scattering
Academics will state that the concept of zeta potential only applies in infinite dilution...
Miguel Pereira-Silva (DI or distilled) Water is about the worst medium to dilute small particles (either solid or liquid). Stabilizing agents and surfactants get diluted out. The ideal dilution medium is the so-called 'mother liquor' - the same content (ionic species, surfactants) of the continuous phase as the undiluted material. You risk destabilizing a system by dilution in DI water...
It may not be possible to answer this generically for all cases.
I would suspect that zeta could become stronger on dilution [like the effect in https://www.materials-talks.com/zeta-potential-in-salt-solution-or-any-other-ions/ or https://www.malvernpanalytical.com/en/learn/knowledge-center/application-notes/AN101104ConcentratedLipidEmulsions.html ]. When a sample becomes very dilute, the variability in the results will go up. In a very concentrated sample, the apparent size may get smaller due to multiple scattering.
- Badges
- Science topic
- Similar topics
- Biological Science
- Biochemistry
- Biochemical Techniques
- Analytical Chemistry
- pH