acetic acid or TFA? - (Feb/24/2009 )
Wht acetic acid or formic is suggested to be replaced by TFA?
Can any1 answer me?
Use of these reagents depends upon the technique you are using.
In reverse phase HPLC:
Formic acid is a counter anion that masks the charges and thus increases the hydrophobicity for better retention on the reverse phase column. TFA is better as it absorbs less (absorption in UV) and is a better ion pairing agent as compared to formic acid
In ESI-MS under -ve ion mode:
There is a lot of signal in the negative ion mode when one uses TFA, so here formic acid is preferred. Also the ionization with TFA is not that good.
Hope it helps.