[mehc]

I am using liquid extraction with water and ethyl acetate to extract phenolic compounds in organic layer.
After shaking my aqueous sample with ethyl acetate,  almost always a foam/emulsion develops at the interface  of two layers which does not disappear/decrease on standing.

I also tried very gentle mixing of layers  but there was no improvement.
I also checked if it was due to some constituents of my sample and mixed simple water and ethyl acetate. But the foam again formed in this case and doesn't disappear on standing.

I am confused about its effect on extraction. Will this foam reduce or lessen the proper extraction of "desired compounds" into organic layer???
How can its formation be avoided?

I highly appreciate any help or suggestion.

Thanks.

[MissPhosgene]

  I would think that the foam you are looking at is an emulsion layer. Since you have tried to be gentle with the sep funnel, it's probably due to to the types or groups you have on the aromatics. One thing you could try is dissolving a salt, such as sodium chloride, to saturation in the water layer.

[skbuncks]

  I would think that the foam you are looking at is an emulsion layer. Since you have tried to be gentle with the sep funnel, it's probably due to to the types or groups you have on the aromatics. One thing you could try is dissolving a salt, such as sodium chloride, to saturation in the water layer.

It may not be strictly necessary to use a solution of NaCl. Once you have shaken your sep funnel etc allow the layers to separate as much as they can and then introduce a few mls of sat brine from a pipette to the sides of the sep funnel (squeeze it in a circular motion around the insides of the neck with gentle swirling of the sep funnel). If this doesn't work then as suggested you will need to either increase the density of the aqueous layer or, if you are able too, perform the extraction at a higher temperature (say 30ºC).

skb