IPEN information

Record: 371

Category: General
Product: C18 (non shodex)
Sample:

Question
I am a student of Masters of IPEN and I am developing a new radiopharmaceutical for PET / CT, the 18F-FAC (fluoroacetate), but I’m not getting results in HPLC. I have used a C18 column with the solvent ethanol / water (10/90), but there is no separation of the 18F and 18F-FAC.

Answer
Are you follwing a method used by someone?
Since F and F-FAC are probably in ionic state under your mobile phase, I think they are not retained on RP system.
I am wondering if you can use buffer to control the pH of mobile phase.
e.g. http://shodex.net/index.php?seitenid=1&applic=1407
By using acidic condition, two components will become non-polar, suitable for the RP analysis.
If controlling the pH does not work and if you need to work with a C18 column, next step might be use of ion-pair reagent.
I would recommend you to try changing the mobile phase pH first. As I indicated in the last email, you may use acidic buffer like 5mM NH4H2PO4 (pH 2.4).
Other options may be 0.3M sodium phosphate buffer (pH 4.4) or combination of acid and methanol/ethanol/acetonitrile.
e.g. 0.1%acetic acid (aq) or phosphoric acid/organic solvent =70/30.

I’m sorry to say but I cannot say which one will work the best.. It will require you to do trials to optimize the condition.
One mobile phase may work better over the other.
Please do not leave the buffer solution in the column at the end of the analysis.
If you use buffer, please flush the column with mobile phase without buffer or water and then fill with 10% organic solvent (MeOH/EOH/ACN) for short term storage. For longer term storage, please use 70% MeOH.

 
 
Additional Comments

Download or Print PDF