I have been working on a method for quite a while now and I suspect a contaminant/degredant in the TEA I am using in my mobile phase (during buffer filtration, the filter (tried nylon, poly carbonate and C18 extraction)becomes pink in color). The buffer contains H2O and TEA pH adjusted to 2.1 with phosphoric acid (creating TEAP). Unfortunately, after trying multiple lots of TEA, I still see the same problem. I have contacted the vendor(s) and they assure me the TEA I have been using has no stabilizers added. Using a C18 guard cartridge even after filtration show the pink substance on the guard column. Problem is, this mobile phase works extremely well for resolution of component peaks in my sample, but the contaminant/degredant is affecting accurate quantitation for the chromatography. Two questions:

1) has anyone seen similar problems using TEA in their mobile phase preps? and more importantly,

2) Can anyone suggest a viable alternative to using TEA which would produce similar chromatographic resolution/ retention?

We usually works with TEA in our mobile phase and I have not seen any pink color in the filter if the solution is preapared just to use. If you try to reuse an old phase with TEA is a waste of time !!

Good luck

This problem rings a bell with me. Almost two decades ago we had the same problem crop up. We found the only solution (pardon the pun) was to buy the TEAP commercially if I remember correctly. And we did not have success immediately in finding a vendor with good material. The pink contamination is a side reaction to the mixing of the base and acid phases. I don't remember if adding the two together first in an organic solvent helped or not. Sorry I cannot be of more assistance. You may have to do some research and vary the manner and the amounts you mix together or the temperature at which you mix them to solve your problem.