Chromatography Forum

Hi,

I have a Waters system. Old school workhorse Delta 600 pump, 717 A/S, 2487 dual wavelength UV detector, and 2475 fluorescence detector. In my research I run strictly aqueous mobile phases. Normally mobile phase pH runs from 4.5 - 8.5.

However, I am starting out on some research that is supported by an outside company. For some of the chromatographic work they are interested in having the mobile phase pH very low. They would have me run some experiments at pH 2!

What pH levels do you think would be dangerous for a chromatography system? Could I go to such a low pH and get away from it? I match sample pH to mobile phase pH. For a hypothetical pH 2 experiment there would be pH 2 mobile phase pumping through the system for about a day at a time.

You might be thinking.. what in the world? separations at pH 2? doesn't sound right....

FYI, I am not doing separations. I am studying surface phenomena like adsorptive fractionation and my samples are complex mixtures of organic matter from the environment. I pack my own columns with minerals. I am as much of a geochemist as a chromatographer. My sponsor wants to see how some adsorbate-adsorbent interactions change when the pH is that low.

Thanks in advance for your input,

Dave

I use low pH mobile phases quite often. Make sure your column supports low pH conditions and you should be just fine.

Thanks Paul,

Out of curiosity, how low is 'low'? I pack blank stainless steel columns. -Dave

you should not have any problem with the system unless you start using HCl, SS parts can tolerate pH below 1 (and lower). You only need to worry about decomposition of your minerals and organic compounds. Is low pH/acid converts your compounds to something else....things like that.