What are the techniques and requirements that should be used to measure the zeta potential if they are dispersed in toluene?
Hi Anchal,
You can indeed measure zeta potential in toluene.
Consider chemical compatibility for your measurement system. Depending on the instrument that you have access to, some cuvettes or cells may not be suitable for use with toluene.
When measuring zeta potential in organic solvents, you may find that default measurement processes may not work favourably as the conductivity of the sample is low.
If you are using a Zetasizer instrument, you should be using the Dip Cell with a glass cuvette, and Low Mobility Mode in the Analysis settings. The low mobility mode applies a voltage over a longer period in order to allow the electrophoretic motion to be better detected.
Other cells such as the disposable folded capillary cell would not be compatible.
Hi Anchal,
You can indeed measure zeta potential in toluene.
Consider chemical compatibility for your measurement system. Depending on the instrument that you have access to, some cuvettes or cells may not be suitable for use with toluene.
When measuring zeta potential in organic solvents, you may find that default measurement processes may not work favourably as the conductivity of the sample is low.
If you are using a Zetasizer instrument, you should be using the Dip Cell with a glass cuvette, and Low Mobility Mode in the Analysis settings. The low mobility mode applies a voltage over a longer period in order to allow the electrophoretic motion to be better detected.
Other cells such as the disposable folded capillary cell would not be compatible.
To add to Alex's excellent answer, I would ask a few questions.
- For what reason are you measuring zeta potential in toluene. What is it going to tell you in your opinion? How will you be able to alter it?
- How will you interpret the result of any value you obtain?
@ Peetam I would ask where you obtain such a standard alumina in toluene sample? Zeta potential is a holistic property of the system - solid + continuous phase - so there can't be the zeta potential of a solid
Chemical compatibility will be a big issue, as Alex, raised, and most plastic cells are unsuited to toluene.
Zeta potential measurements in hydrocarbon liquids can be very sensitive to moisture levels. I've measured cross-linked polystyrene latex particles in toluene deliberately as a function of water concentration in the tens of ppm range and obtained notable differences. How you go about interpreting such data is another matter entirely as, in fact, is how you calculate a meaningful zeta potential from the electrophoretic mobility. The traditional Smoluchowski, Huckel and Henry approaches don't apply.
(The interesting thing about the above system is that the particles swell and because of the similarity between the monomer units and the toluene there is very little attraction between the particles).
Hi Arvind,
Do you have a query relating to my earlier answer or are you just reiterating it?
As indicated, it is possible to measure electrophoretic mobility of nanoparticles in toluene.
Due to its low dielectric constant (~2.4@25C) compared to water (~78.5@25C) the use of an arrangement with closer electrode spacing (typically a dip cell) is necessary to achieve significant effective field strength to influence the particles.
There are several publications where electrophoretic light scattering from a Zetasizer has been used with samples in toluene: https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=zetasizer+toluene+electrophoretic+mobility&btnG=
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