Rotary evaporator waste solvent , any benefit?

Basic questions from students; resources for projects and reports.

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Hi

After doing extraction lets say in only 100% DCM then we use a rotary evaporator to evaporate the solvent. The solvent waste ( after being deposited in the other flask)

Now

Can I reuse this solvent again other than throw this solvent and use new one?


I feel If the solvent waste give smooth baseline in LC why we don't reuse it better than wasting money and generate more waste.
No! Toss the waste out! Just because you get no peaks on an LC does not mean there is no crap there since it may be fully retained by the HPLC column.
mmmmm even If I subtract the solvent background from the sample. I guess that the peak of analyte of interest in ( clean solvent and waste solvent ) stay the same. I know It is not truly scientific. Not sure but I highly respect your opinion
A lot would depend on what you are extracting and concentrating in the rotovap procedure. Can some of what you are isolating also boil off into the waste solvent, if so it would no longer be suitable for purpose. What is the moisture content of the solvent after evaporation? Is it acceptable to be used again if there are trace impurities in it? Can it be repurposed as a cleaning solvent instead of being used in the extraction?

You would definitely want to redistill it and get an accurate boiling point range to get a better idea of the purity.

Without knowing all the details of your extraction nobody can give a accurate assessment of the waste, so it is better to error on the safe side with disposing of it.
The past is there to guide us into the future, not to dwell in.
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