Would you mind prescribing more about your procedure? I could not understand why you are using trifluoroacetic acid and is there not any substituent solvent?
I am using mobile phase A as HPLC water containing 0.1% TFA and B as methanol
it was from one preocedure I read. My queation is after purification a little TFA will be there in my pure compound and how it will give a good NMR without removing this..? and if so any easy methods available to remove TFA?
In your question you mention 1 % TFA, but in your reply it's 0.1 % TFA. I'm assuming the latter is the correct one?
The b.p of TFA is indeed 72 C, but it would form an azeotrope with water with a b.p of 105 C. If you want to remove traces of TFA, you could use Polymeric SPE devices. Polymer Labs (acquired by Agilent Technologies) has anion-exchange SPE for TFA removal.
One can use a C18 column or cartridge. Condition the cartridge with methanol followed by water. Evaporate the methanol from your fractions, then load them on the cartridge. Wash with water; the C18 hold your compound while the water washes the TFA. Elute your compound with methanol. This procedure both removes the acid (this method can also be used for salt buffers), concentrates your compound, and also replaces the water with methanol, which is easier to evaporate. I've attached a draft application note describing the procedure for someone that has a flash chromatography system. The procedure can also be used for removing DMSO and similar solvents from NMR samples.
Assuming your terpenes are very non-polar, you can also try evaporating the organic solvent from your fractions and extracting the terpenes into ethyl acetate, dichloromethane, or another solvent. Wash the organic extract a couple of times with aqueous saturated NaCl to remove residual TFA, dry over sodium sulfate, then evaporate the extract. My C18 method above works fine, this may be a little easier and cheaper...
I am also using 0.1TFA (v/v) in HPLC, to separate flavolignans with MeOH/H2O.
When I rotate I see some brown substance. How can be sure that the TFA is already removed? It will be enough evaporating?
I'm glad I found this post, my problems with TFA is my compound became TFA salt after remove solvent. The compound was dissolved in MeOH, partially dissolved in EA, I will use Jack's method to flash the compound through C18 again with MeOH
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