TFA for Ion pairing

[MestizoJoe]

Does anyone know the best TFA concentration to use for ion pairing? I know the column can only adsorb so much. Using a concentration higher than that which will cause max adsorption is useless, but I don't know the concentration. It's probably dependant on organic concentration, too.

Thanks,

[SIELC_Tech]

The impact of TFA as ion-pairing reagent for analysis of small molecules is overrated. What kind of analytes you are trying to analyze?

[MestizoJoe]

I'm sort of asking what the rating is.

I know I can use other IPR's but unfortunately I don't have time for that.

[SIELC_Tech]

The rating is 1

Concentration of TFA depends on your analyte and column. You need to make sure that your column can tolerate low pH (2 and below). I would start with 0.1% TFA

[MestizoJoe]

I am guessing going above 0.1% won't help much. I looked at Practical Method Development by Snyder and he has some really nice graphs showing retention vs ion pairing reagent concentration but nothing for TFA. Probably because it's better used as a modifier. Oh well haha.

[SIELC_Tech]

That is because TFA is not very good IP, try something else:
http://www.tciamerica.com/useful-info/p ... A1084E.pdf

alternatively you can use Primesep column with IP reagent embedded on the surface of silica gel:
http://www.sielc.com/pdf/SIELC_June_2004.pdf (in these applications TFA is not ion-pairing reagent but source of ions facilitating ion-exchange mechanism)
http://www.sielc.com/pdf/SIELC_June_2009.pdf

We never used IP in our lab, for us IP is dead