Let's say I have 100 mL of an aqueous solution and I wish to reduce the volume to 5 - 10 mL. What's my best option?
- Rotavap is ruled out because we do not have a vacuum pump that can create sufficient vacuum, also I wish to avoid heating up the solvent too much since the solute may not be stable at higher temperatures
- Freeze drying is also not possible because the solution contains a high concentration (6 M) of guanidine hydrochloride, and it was found that such a solvent is likely to melt on the lyophilizer
Any suggestion is appreciated!
Hi,
if you have a rotary evaporator, and any vacuum pump, you can use both and pass dry air or nitrogen though th roty. Heating as high as possible will accelerate. Rotary speed as high as possible.
Hope it helps
Andreas
Dear Rui-Liang Lyu , rotavap could be the best option, but water is always tough and without a good vacuum pump it will be difficult to remove the water, even if you can blow some dry air or nitrogen as Andreas Pingel Keuth recomends.
Lyophilization would be my option for 100mL volume... I just checked the melting point of guanidine hydrochloride and it is aroun 185ºC, so it shouldn´t be a problem. However, such a big concentration of this compound would leave you with quite a big amount of solids...apparently this compound crystalizes very well.
It is not my field, but I just have read that ganidine hydrochloride is commly used for protein denaturation, so probably is also your case, and may be what you want is to remove your protein from the solution, and if so you could try to precipitate it. According to the following paper ethanol is a good solution, because guanidine hydrochloride is soluble in alcohol but probably your proteins are not, so they will precipitate and you could filtered the final solution without to worry about water removing.
This is the link:
Article Selective precipitation of proteins from guanidine hydrochlo...
Hope it helps.
Manuel, the problem with guanidine is that it absorbs heat when it solubilizes with water. If you attempt to dissolve it in water it actually cools the solution down. Reversely if you remove the water on a lyophilizer it heats it up and causes the ice to melt. Yes it sounds weird but it's what happened to me.
Precipitation may be a good idea. Thanks for pointing it out.
Thanks Rui-Liang for describing the behaviour of guanidine, I´ve never used it, but it is interesting to know. I hope the precipitation works for you! Good luck!
Hi Lyu,
If no vacuum pump available and you do not want to use heat, the best way is to put your sample in a large beaker or evaporation dish and place it in fume hood and leave it there for few hours or overnight water will evaporate , you can use air bubbling also to speedup, good luck.
Best way is to put your sample in a evaporation dish and place it in fume hood and leave it there for few hours water will evaporate.
@ Salim Y Hanna, Burkhon Elmuradov
This will not work, due to the hygroscopy of the guanidine hydrochloride.
http://gestis.itrust.de/nxt/gateway.dll/gestis_de/014480.xml?f=templates$fn=default.htm$3.0
http://gestis-en.itrust.de/nxt/gateway.dll/gestis_en/000000.xml?f=templates$fn=default.htm$vid=gestiseng:sdbeng$3.0
The result is a more or less oily liquidist
Andreas Pingel Keuth!
Yes, there is a possibility of thick mass formation due to the hygroscopicity of guanidine hydrochloride.
However, this procedure is often used even at room temperature. Because it is very simple, economical and efficient.
Good luck!
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