I was doing partitioning in the field of pythochemistry. I dried my butanol layer over sodium sulfate, rotovap and freeze dried the butanol layer on the lyophilizer. However I suspect there may be some sodium sulfate mixed into the butanol layer. Is there any ways i can desalt my butanol layer extracts, or at least know the level of sodium sulfate in the butanol extracts?
To know if sodium is in your sample is easy done. You should put a little quantity of the sample in the flame of a bunsen witha platinum filament. If the flame turns yellow sodium is present. Another test you may perform is dissolve an aliquote of the sample in water and add a solution of Ba (OH)2, if the sulfate ion is present you obtain a white precipitate of barium sulfate.
Anyway, why you dried the butanol layer with sodium sulfate? The butanol could be easily eliminated because it forms an azeotropic mixture with water. Therefore you should only add some water during the evaporation of the mixture and in the end all the butanol may be eliminated.
It happens normally. Because Butanol after drying on sodium sulphate till have small amount of water with traces of dissolved sodium sulphate. When you will evaporate it , during that stage you will find small aqueous layer is formed, if you remove that layer then your problem will solve. Another way is to heat the Butanol layer (if your target molecule is not heat sensitive) for few minute and observe if any small aq layer is formed or not. If it is there then discard it. One more way is after drying the butanol layer,redissolve it in butanol, filter and and dry the filtrate.
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