We isolated a labdane diterpene from the seeds a locally available plant. It is resinous and highly hydrophobic. So, we dissolved it in DMSO. To obtain 5% DMSO from the stock prepared, we added the required volume of water or aqueous buffer. The solution turns opaque cloudy. What could be the reason for this? Is it spontaneous emulsification (Ouzo effect) or something else?
Many of the labdanes are non-polar, and mixture is hydrophobic, so no surprise that it turns cloudy when diluted with water. Yes, it could be the Ouzo effect.
Dear Mr. Shreekant,
The following articles might be useful to you:
According to F. Ganachaud & J. L. Katz (Nanoparticles and Nanocapsules Created Using the Ouzo Effect: Spontaneous Emulsification as an Alternative to Ultrasonic and High-Shear Devices, ChemPhysChem, Volume 6, Issue 2, February 11, 2005, pp 209-216, Minireview, available on RG), spontaneous emulsification is a phenomenon that has often been erroneously interpreted. The spontaneous emulsification (named the Ouzo effect by Vitale and Katz) "occurs upon poring, into water, a mixture of a totally water-miscible solvent and a hydrophobic oil - and optionally some water - thus generating long-lived small droplets, which are formed even though no surfactant is present". The paper reviewed and reinterpreted the most relevant publications on the synthesis of a variety of dispersions.
J. C. López, et al., (Langmuir, 2002, 18 (11), pp 4258-4262) describe a "New Method to Quantitatively Determine the Spontaneity of the Emusification Process"
I assume that you are interested in adding the diterpene to a buffer solution as a DMSO solution to examine its activity in living organisms. It is known that such solutions become "suspended" as the concentration of the dissolved material increases. You state that your solution turns "opaque cloudy". I do not know if this is a true "Ouzo effect", or a simple solubility problem, but I am not an expert in this field.
Best wishes in your research. AF
As far as my knowledge goes it must be solubility problem of labdanes in aqueous phase.
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