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Author: Subject: Salting-out Liquid-Liquid Extraction
GoldGuy
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[*] posted on 18-2-2014 at 15:17
Salting-out Liquid-Liquid Extraction


It has long been known that the addition of an inorganic salt into a mixture of water and a water-miscible organic solvent causes a separation of the solvent from the mixture and the formation of a two-phase system.
Observations of this "salting-out" phenomenon were made for a number of water-miscible organics such as acetone, methanol, and ethanol.

This salting out often occurs at high salt concentrations. In some cases, the "salting-out" (or perhaps better termed "sugaring out") effect also can be achieved with high concentrations of saccharides.


Any knowledge or experience out there of using a water miscible solvent such as, acetone, methanol, or ethanol to do SALLE?

It seems advantageous to conventional extraction for many reasons:

1. Methanol is about 1/10 of the price of ether where I am
2. Ether/Toulene is hard to intimately mix with water and extremely labor intensive
3. I extract from a fermentation broth and since ethanol is produced as a by product is only makes sense to extract with an alcohol aswell
4. If one could use sucrose for the "sugaring-out" of a fermentation broth, the sugar can be theoretically re-used

Any information as to the salt/sugar concentrations? Or any other pertentent information on this technique for the home scientist would be appreciated

[I copied most of my words from http://www.chromatographyonline.com/lcgc/Column%3A+Sample+Prep+Perspectives/Salting-out-Liquid-Liquid-Extraction-SALLE/ArticleStandard/Article/detail/ 613590]

[Edited on 18-2-2014 by GoldGuy]

[Edited on 19-2-2014 by GoldGuy]
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Brain&Force
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[*] posted on 18-2-2014 at 20:07


The best alcohol to use for salting out is the commonly available isopropanol. Methanol and ethanol tend to precipitate the salt in the water instead, see this thread: http://www.sciencemadness.org/talk/viewthread.php?tid=28399



At the end of the day, simulating atoms doesn't beat working with the real things...
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19-2-2014 at 05:53
GoldGuy
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[*] posted on 20-2-2014 at 08:46


Acetone, ethanol, methanol, are all soluble in sugar.

I out of all I've read it seems that K2CO3 is the best.. but still not suitable for all because it makes a very basic solution.
Use K2CO3 and keep my solution acidic? How?

Im thinking acetone as solvent and MgSO4 (Epsom salt) as the salt. MgSO4 is insoluble in acetone.

Side note: Isopropyl seems to be least soluble in salt solutions and sugar solutions... high bp though

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