Chromatography Forum

Hi,

For PP, protein precipitation, I usually use methanol or acetonitrile.
It is said that you have to use a volume (sample:solvent) of 1:1 for acetonitrile and 1:2 for methanol.

Now, I am working on a method where I would be interested on testic acid perchloric as a solvent. I think that in this case you can use lower volumes, but could anybody give me sample:solvent relationship? How lower can I go?

Thank you very much!!!

I cannot say for perchloric acid but we tested TCA and sulfosalicylic acid as we were interested in particularly polar compounds which could still be retained on 100% compatible C18 columns. We discarded the use of sulfosalicylic acid since it was strongly retained on C18 columns and caused very intense ion suppression for our early eluting peaks. TCA was found to efficiently precipitate proteins at a concentration of 5% in water. However, such concentration had a strong impact on peak shape so we had to dilute to 0.1% TCA or less in the final solution. Hope this helps.