You may try to evaporate small volumes in a more big flask. Another solution may be the use of some anti-foam agent but you must evaluate before using it the potential interference of this compound in the further analysis on your extract.

Using a pear-shaped flask (rather than a spherical round bottom flask) helps a lot. And, don't fill the flask too much and use a high rotation. (described in the book: Natural Product Isolation (Eds. Satyajit D. Sarker, Zahid Latif, Alexander I. Gray)

If you have a small quantity of the extract, you can do the evaporation on a water bath. Though it will take time but other problems will not arise. Once it will get heated, you will see an increase in the rate of solvent evaporation.

U can also a sand bath alternatively keeping a constant look during the heating process. Because your extract contains water, you can use this process at least for a faster result.

First try to evaporate methanol on hot plate (35-40 C) then use lyophilizer if available.

You can add small volume of n-BuOH to the extract. But, you have to keep the presence of n-BuOH until the end of evaporation.

I also agree with Nahata sir,

You can go with his ans.

We also published work on saponins. You have to use rotory evaporator for evaporation of solvent. I also faced same problem. Divide your solution into 2 to 4 round bottom flasks, then dry it. When you will get slurry, put into -20C for two hr. Then go for lyphalizer for powder.

Gudgluck

:)

As Sir Seyed stated, you can freeze dry your extract. You can also try using other solvents in extracting your saponins. Use solvents which are less miscible with water so you can easily remove them later on.

You can also separate the solvent from your extract by using distillation assembly. Entire solvent will be recovered in the receiver and when 15 to 20 ml of the solvent is remaining in your heating flask, you can evaporate it on water bath as said above. I have used this method and it was hassle free. You may also try.

Rheam, You could try do perform an atomisation (lab scale) or a lyophilization if your objective is to obtain a dyied extract.

If you want to procced with your rotavap to reduce the volume of your solution you must increase the water temperature of the bath and decrease the preassure (150 to 180 mb for a bath température of 68-70°C). sometimes it works ......

Another solution could be to add an antofoaming agent.

Dear Everyone,

Thanks a lot for your precious comments. I used a pear-shaped flask. I added in small volume with the addition of n-butanol. I started on rotavap @ 70C followed by water evapration on water bath

Thanks again for your precious answers

Best Regards

Reham

@Reham Mekky

Nice to know that you combined all the suggestions and got the fruitful result.

Gud Luck and best regards

@Alok Nahata

Thanks for your kind wishes :)

as per my experience rotavapor temperature should not go beyond 30° in any case. Lyphplisation/freeze drying will be the best alternative, without loosing the contents of the extract.

@Prof. Ravi Sharma

Thanks very much Prof. Sharma it is very kind of you

You add only small amounts of dist. water into methanolic extracts and evaporate this because water is miscible with MeOH. You repeat this procedure until the all MeOH evaporated. You can take smell if MeOH present or remove. If you sure, there is no MeOH smell, then your condensed extracts (only aqueous extracts) keep in freeze at -20 degree C about an hour for freezing. After freezing you will subject this sample at freeze dryer. Then you will get dried samples. This is my experience. I already success to apply this techniques.

@Md. Nazrul Islam Bhuiyan

Thanks very much I do appereciate your comprehensive answer

To remove water without foam one solution is by adding a antifoam agent.

you can also remove water by taking small quantity of the aqueous extract in the RB flask and place it on the rotavapor.the waterbath temperature should be 35-40 degree and let the flask be placed just above the waterlevel so tht it have afeel of heat and then slowly rise the vacuum to maximum in a controled way while the flask is in rotation mode.Once the solution in the flask is stabilised under high vacuum the flask can be immersed to half in the waterbath.This will help you in a way once the vacuum is attain tht your extract is not at high temp and the actives are intact but a little time consuming process.

You have to use a small amount of the extrat and schould add drops of n-butanol to the extract. At the end when you have a problem of n-butanol you should add drops of water for better evaporation.

Is the evaporation on going or ended? What can you do, it depends on waht you have in your lab. good luck

You should release small amount of the extract i.e. drop by drop in rotary flask and don't let to store more liquid extract in the flask until dry the first drop . It will take time but solve your problem.

@ Muhammad Afridi

Thanks very much for your help.

Do it on small volume of extract and keep rota-vapor temperature lower than 40° C.

@Yadollah Bahrami Thanks for you valuable help and support. It is very kind of you.

I echo Nadine Bohni about using a pear-shaped flask (rather than a spherical round bottom flask) helps a lot. Do it on a very small volume of extract each time. Adjust the pressure using the valve.