Chromatography Forum

Hey folks

We are starting some work with a molecule that contains three iodine atoms (the molecule is iopanoic acid). I have never come across this before in HPLC.

Does anyone know if I might expect any kind of reaction or strange behavior on a standard reversed phase column.

Any "heads up" would be very much appreciated.

Much thanks in advance.
Adam

I believe it should be fairly strongly retained on a C18 column.

best wishes,

Rod

pH will certainly play a role. You may want to start off around pH 3 where the molecule should be mostly neutral to get best retention. What detector are you using?

You might try 0.1% Trifluoroacetic in your mobile phase which converts your acid group to COOH rather than COO- giving you good potential for retention on a C18. In short though as long as you're below the pKa you should be alright.

I suspect that nitrogen will start to protonate below pH3 (according to Marvinsketch), so if you go too low your retention may suffer. That's why I suggested pH 3 which you could get with formic or acetic acid.