Dear All,
I am looking for a data on the subject above. P. Sadek, in "HPLC Solvent Guide" only tells us about bacteriostatic activity of ACN, which is >=15%.
I am interested in the other popular modifiers also, including MeOH, Isopropanol, THF. Have anyone of you got any information (or experience) about it? To complicate things, we should be awared that in the presence of a buffer above pH~4 such bacteriostatic conc. should differ, too.
Any published references?

Best regards,

Maciej Turowski
Kyoto Institute of Technology

Some years ago I was doing a lot of single-column IC using things like phthalate buffers in the pH 3 - 5 range. My recollection is that 5-10% MeOH in th mobile phase would extend the lifetime of the buffers from 24 hours to 4-5 days. I don't have any documentation on that, however.

-- Tom Jupille / LC Resources Inc.

I attended an interesting seminar on HPLC trouble shooting last nigh. The speaker was talking about the various solvent degassing techniques. He made an interesting comment I wish to pass along. The speaker said "the only benefit I found with Helium degassing (sparging), is that it stopped the pink slime from growing in my buffer". "Apparently the local bugs (in his geographic area) need Oxygen to grow, and Helium sparging removes all of the Oxygen." He got a few laughs from the audience.

Although, I do wonder, is there any merit to this

This doesn't directly address your question, but Agilent Technologies (nee HP) now recommends amber bottles for your aqueous mobile phase. They even have a little pamphlet on the topic. Contact your local rep.