Chromatography Forum

Hello everybody

I am developing a method for HPLC-analysis of Risedronate. I have 1 mM EDTA in my mobile phase to prevent tailing of my main peak. Unfortunately EDTA causes system peaks.
Here at Chromforum I have read, that one can use NTA og DTPA instead of EDTA. These compunds should make system peaks at other retention times than EDTA.
Can anyone suggest how much NTA or DTPA I should add to my mobile phase?

Thank you for your help.

Susanne

Suzanne,

I would suggest that you substitute NTA, DTPA, or CDTA at the same molarity that you use for EDTA. It's possible let you might need to double the concentration for NTA relative to EDTA but I would try the same molarity first since most complexes are 1:1 with these chelating agents.

I flush the column with EDTA solution - methanol for 20 column volume before I run with mobile phase. It help to reduce tailing.

Thank you for your replies.

Chris Pohl: I will try 1 mM NTA or DTPA. Thanks:)
syx: Since I plan on analysing many samles in a row, I don't think your suggestion will work for me. But thank you anyway:)

Susanne

Not prior to each run, but the initial run of the system. It helps to reduce the tailing on mine.

What column are you using?
Try Dionex Ion Pac AS4 with EDTA mobile phase.