@ Shwetha Karanth
I have a question from Shwetha Karanth that I will post so that others can be engaged in the debate:
Hello,
I would like to measure size of my microemulsion in organic solvent. however the operator of malvern instrument asks for aqueous solvent only because of the cuvette constraints. Is it never possible to measure organic samples in Malvern Instruments.
Thanks in Advance
Shwetha Karanth
I have some confusion with your question. Are you saying that you have a water-in-oil emulsion that you'd like to measure in an organic solvent? What solvent are you referring to? Is this solvent the same as your continuous phase in your microemulsion? What Malvern system are you referring to?
There are a number of cuvettes available for the system. You can select a quartz or glass one for compatibility. The plastic cuvettes are made of polystyrene and resist some organic solvents. However, they are relatively cheap and quick to use. See attached.
It depends on the liquid and the cuvette material. Two common plastics for cuvettes are polystyrene (PS) and polymethylmethacrylate (PMMA). Liquid-plastic compatibility charts are widely available on the web, e.g.,
http://sevierlab.vet.cornell.edu/resources/Chemical-Resistance-Chart-Detail.pdf
It shows that iso-propyl alcohol has excellent compatibility with PS but not recommended with PMMA whereas the opposite is true for hexane.
If the organic liquid you are using is non-polar then you should use the dip cell with a standard 10mm cuvette and not the folded capillary. This is because the electrophoretic mobility will be so small that a strong electric field will be necessary.
(My background for this is that I invented phase analysis light scattering - known to most people as the "fast field reversal/monomodal" mode for the Nano ZS - specifically for measuring dispersions in non-polar liquids. Typically mobilities are factor of 100 to 1000 lower than for aqueous. I used quartz cuvettes for my PhD work.)
John.
EDIT - per Alan's comment, by "liquid" I mean the continuous phase rather than the droplets. I don't use "solvent" because you aren't dissolving anything. But that's me!
Thanks, John for adding to my answer. It all depends what the solvent actually is. I'm also concerned that a oil-in-water emulsion is going to be placed into an organic solvent so just wanted to confirm that it's a water-in-'oil' emulsion.
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