this good question. you can evaporate the HCl using water bath at 100 degree delicious , this totally removing the chlorine gas.

Dear Zain,

The most appropriate method will depend on what you need to do with the resulting sample. As suggested a hot water bath / simply heating will remove the HCl, however, there are questions as to where that HCl / Chlorine gas will go ... make sure you have a good laboratory extraction system!!!!! In such cases, or with a nitrogen blowing system then your sample is at the temperature of the water bath all the time ... this can be quite hot and may affect your downstream results. A nitrogen blowing system does not have to be hot, but if it is done at ambient or even say +40°C then it is really slow. Evaporating under vacuum has the advantage that the reduced pressure causes reduced temperature boiling, so you can go fast and safe (low temperature). I'm not sure why your rotary evaporator is slow - I'd check the vacuum level in the system, for water best results are found with a pressure of 8mbar. At this pressure water boils at +4°C. If you have many samples to process, and need a safe way to do it, then the EZ-2 HCl resistant system from Genevac is designed for this purpose, however, it is expensive!

Kind regards,

Rob

Well I tried the method suggested by Melese. Yes it worked. The HCl evaporated off at 100 degree C. However, Rob mentioned about the resulting sample, it questions me whether the flavanoid degraded at high temperature or not? Mind give opinions regarding this.

What happen to the flavanoid inside your sample is dependent on what sample your are dealing with...Is it leaf, seeds or nut....The stability of your material to heat is dependent on how much heat it can withstand. You can actually use several solvents and test their the total flavonoid contents (TFC).