How to prepare 4M ammonium sulphate solution? - Ammonium sulphate precipitation (Aug/21/2005 )

Hi,

I would like to know how can I prepare ammonium sulphate solution with concentration of 4M. I tried to dissolve ammonium sulphate salt in water but it won't go in even overnight and long hours of stirring both in room and cold temperature.

Thanks for helping.

Haohao

I tried to dissolve the ammonium sulphate again today and finally can get them into the water. I added the salt little by little and slowly with stirring going on. Eventually it dissolved.

I think you have found out why the salt is added directly to protein precipitation solutions

Daniel

DNA sequencing

I read some journals about ammonium precipitation of proteins by adding the ammonium sulphate salt directly to the protein solution. However, some of my collegues suggest that I prepare ammonium sulphate solution and then add to the protein solution slowly to prevent denaturation of my protein and precipitating out unwanted proteins instead. Would there be a big difference between adding ammonium sulphate salt directly or use prepared solution of 4M ammonium sulphate?

Thanks.

Haohao

As long as you add slowly it won't matter if you use salt or solution. The major advantage of using the salt is the final volume will be less. This can be quite an advantage if you have a large volume to precipitate.

Daniel

DNA sequencing analysis software

Thank you Daniel, really appreciate it for you replies.