Chromatography Forum

I remember seeing an article re a TEA based buffer for analysis of bases.

I didn't take a copy at the time and can now not remember where I saw it.

Think it was an application from either Agilent or Waters.

Can anyone advise of a TEA based buffer for analysis of bases ?

Need as a starting point for some method development.

Ta

TEA is from applications where acidic silanols in Type A silica caused peak tailing of bases. Adding TEA to the mobile phase at ~ 20 mM blocked these sites and improved peak shape. If you search this on the web you'll find some articles.

I routinely use 0.1%TEA as pH modifier in our reversed-phase systems that require high pH for separations (bases). As I am in the preparative chromatography business it is easier to evaporate off as it is volatile. Be careful with your choice of columns because most silicas cannot handle that pH (10-11). The newer hybrid stationary phases such as Waters Xbridge and Phenomenex Gemini have better lifetimes in these extreme pH ranges. Depending on the strength of your bases you might be able to use pH 8-9 where more columns are robust.

Good Luck,

I assume that you want to use a buffer at the alkaline pH. An excellent choice is ammonium bicarbonate, around pH 10.

Uwe,

How about the pH drifting of ammonium bicarbonate? There have been conflicting suggestions in the past regarding the "stability" of this buffer...

Kostas, my experience (from my ion chromatography days) is that any alkaline buffer is subject to pH drift due to absorption of CO2 from the atmosphere. Our SOP was to use a CO2 trap attached to the vent tube on the solvent reservoir.

We are using alkaline buffers all the time, and especially ammonium bicarbonate at truly alkaline pH without difficulty.

There was discussion about drifting of an ammonium bicarbonate buffer at pH 7. It was a dirty trick that I tried at some point in time to get an MS compatible buffer at pH 7. THIS did not work, due to the fact that we slowly lost CO2, and the "buffer" migrated to alkaline pH.

Ammonium bicarbonate is a beauty, due to the near overlap of the pK of the ammonium buffer and the bicarbonate buffer. You double the fun with double the buffer capacity...

Ammonium bicarbonate is a beauty, due to the near overlap of the pK of the ammonium buffer and the bicarbonate buffer.

That makes sense (which is why I never thought of it! ). We were using sodium bicarbonate/sodium carbonate systems at the time.