Chromatography Forum

Hi,

I'm looking for HPLC columns stable from pH 10-14 that can be used with an ELSD. Thus, there needs to be low bleed; so silica-based columns are out. It's also preferable if the column chemistry can retain hydrophilic analytes. So far I've come up with the following:

a. Thermo Hypercarb (graphite)
b. ZirChrom-CARB (zirconium)
c. ZirChrom-PBD (zirconium)
d. Shodex Asahipak NH2P-50 (polymeric amino; stable to pH 13)
e. Supelco apHera Amino (polymeric amino; stable to pH 13)

Any other ideas? Also, I'm not sure how easy the zirconium- or graphite-based phases are to develop methods for.

-Ryan

How about polymeric columns, such as the Hamilton PRP range?.

MerckSeQuant ZIC-pHILIC (polymeric zwitterionic HILIC column)
I have used one for 4 weeks at pH 11 at 55 C without any deterioration.

If you are looking for RP columns based on polymer Showa Denko and Hamilton columns are based on PSDVB, and a 3rd manufacturer, Tosoh, is using Polymetacrylate.

For the lower range of your intended applications, you can use XBridge C18 columns, which are at room temperature stable to pH 12. For more routine applications and at higher temperature, we typically recommend to use pH 10.

Hello,
my first post/reply ever here...

What about the Gemini series by Phenomenex? They are stable up to pH 12.. unfortunately, although it is quite a lot.

And another question related to the psot: What buffer would you use?
I have been using amm. acetate 10 mM pH5, but figured out that adding triethylamine (TEA) 1% the separation is much better (although the pH rises to 9-9.5-10 (I dont remember exactly). Adding TEA and decreasing the pH to 5 again doesnt work. Would it be a good buffer? i mean amm acetate 10mM with 1% TEA? I know amm acetate can be used also at pH 9.5 but I am not sure if adding TEA would be enough to get it stable.

Thanks

What kind of compounds you are analyzing? Why do you need very high pH? Are you trying to push you basic compounds in "non-ionized" state to get retention for very polar basic compounds?

Guys: Thanks for the advice. I'll report back on the bleed for some of these at high pH.

Edit.

Vlad: I have a couple applications, and yes bases at high pH are one. Mainly, I want to look at these for the sake of seeing what can be done there.

Victor: I have a couple buffers in mind such as TEA acetate, DEA acetate, NH3 formate, etc.

Here is our response to high pH separations ("Is There a Mystery in HPLC Separations?"):
http://www.sielc.com/pdf/SIELC_June_2005.pdf

All the buffers that you intend to use have pKa's that are within the stability range of the XBridge C18 packing. No problem.

Jordi Labs has DVB columns
BioChrom Labs has PS-DVB columns
Both are pH stable 1-14

Ok, so TEA 1% in Amm acetate 10mM is a good buffer. Good. I intend to use that then and need to be sure than it will keep stabel through the entire runs.

Thank you for the info!

As far as silica based colums, well hybrid silica, i have found Xbridge to be the most robust column followed by geminiNX. This is when running pH10 ammonia based buffers at 40C on (UV detection).