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Any problems/impurities with TFA?
Posted: Fri Feb 04, 2005 5:40 pm
by redzilla
Hi,
Has anyone experienced mobile phase impurities when using TFA? I use 0.1% TFA and methanol, and I've been having a ton of junk showing up all the way across the baseline. I've run the methanol alone, and the baseline is much, much cleaner.
My TFA is >99.0%, but I'm wondering if it has degraded. Any experiences with this? Suggestions on shelf life? (of the TFA alone, not as a 0.1% solution)
Side note, I've ordered more TFA, but I'm hoping for some tips on how to maybe "clean up" the mobile phase in the mean time until my order comes in (I have a ton of samples to run!).
Thanks!
Posted: Fri Feb 04, 2005 7:43 pm
by adam
TFA can be problematic. I think it is inherently unstable, and reacts with oxygen. A very simple way to significantly reduce this problem (assuming you don't want to change the method) is to order TFA in 1 mL ampules, instead of in a large bottle. This way the TFA does not sit around for a long time - exposed to air - before it is used.
I think we get ours from JT Baker.
Hope that helps.
Adam
Posted: Sat Feb 05, 2005 7:47 am
by maris
At low wawelenghts TFA may couse the problems. Purity of 99.0 doesn't mean too much. There are some manufactures of HPLC grade TFA, loon on web and re-try.
Re: Any problems/impurities with TFA?
Posted: Sun Feb 06, 2005 8:41 pm
by dcobice
Hi, Just i try to devolopment a HPLC methods with a gradient elution, the mobile phase is water and methanol with 0.1%.I have no problem with the baseline altougth I have seen only a pair of peaks at the end of the run.( maybe solvent peaks) at the end of the run, the concentration is about (65% of methanol)
Try to buy ampulles of TFA, in our case I get it by PIERCE and I havent seen any issue in baseline.My wavelength is 220 nm.
Regards!
TFA reaction with MeOH
Posted: Mon Feb 07, 2005 5:12 pm
by Rob Burgess
We've seen that TFA can react with MeOH to form the corresponding ester. Could this be your problem with your MP? The best way round this would be to mix TFA and MeOH online rather than premixed.
Posted: Mon Feb 07, 2005 5:18 pm
by redzilla
Thanks for all the info. This has been a problem only within the last month or two, that's why I figured something might be wrong with the mobile phase (new column, so I ruled that out). The mobile phase is indeed mixed and degassed online. I'm hoping my new order of TFA will help clear everything up, but unfortunately it won't be here for a few days!
I'll see what I can do in the meantime...
Thanks!
Re: TFA reaction with MeOH
Posted: Mon Feb 07, 2005 6:57 pm
by dcobice
We've seen that TFA can react with MeOH to form the corresponding ester. Could this be your problem with your MP? The best way round this would be to mix TFA and MeOH online rather than premixed.
A question? can TFA react with Meoh in mobile phase containig 0.1% in 80:20 water:methanol?It´s posoble? I have seen an esterification process on a Drug substance Impurities during a run in my gradient profile.
It´s posible? the column temperatrure was 40.
Thanks!