Sometimes we use a huge amount of solvents for extracting our targeted molecules. Some solvents are so expensive and for this we recycle this solvent for further use to save our money. But one thing is the quality of the recycled/recovered solvents is a critical factor in controlling the quality of the resulting natural products in pure form.
Thank Mr. Laurent. But can distillation remove all impurities (minor also) from used solvents?
It all depends what are the impurities, Most "solid" will not get distilled. our biggest problem will be if you are dealing with mixtures of various solvents.
have a look at: Purification of Laboratory Chemicals from Perrin and Armarego
We can use the same recovered solvent for the extraction with the same materials next time
The solvent properties should be determined to see if it is same with the original form.
Knowing the composition of the recycled natural solvent before use will be better.
Recycling is the best method to preserve the solvent as large quantity of solvents are required for extraction purposes. If you are using a soxhlet apparatus for extraction, you can use the same for recovering the solvent also. Just continue heating the receiver flask and you will get the distilled and recovered solvent in the portion of the assembly where u fill the crude drug. Don't allow the cycle to run and remove the distilled solvent for further use. This method is used widely in most of the labs to preserve the solvent and reuse it.
Use the recovered solvent for extraction again. I would suggest to not to use it for other experiments like isolation and fractionation. As far as extraction of crude drugs is concerned it is OK and can be used. Prefer to use it with the same drug again.
Regards
Hi. For most common solvents the distillation process is sufficient. We distilled solvents using the techniques described in "Purification of Laboratory Chemicals" (W.L.F. Armarego). NOTE: We use distilled solvents for extractions, for advanced chemical analysis or biological analysis we prefer to use new solvents.
Be careful, if the solvent you want to recycle has been in contact with natural extracts I dont recommend the distillation because you can have volatile oils in that extract which will evaporate together with your sovlent.
Thank every body for nice discussion. May be, we can not use recovered/recycled solvents in all experiment especially if our original sample contain some volatile compounds. If we confirm, our sample has no volatile compounds, then we can use this solvent.
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