Ask help for seperation DOTA & DTPA related compounds!

[Z.-X. JIANG]

I have some difficulties in seperation some compounds like DOTA & DTPA which contain 3-4 COOH groups and 4 tertiary-amine groups. Those compounds came out either at the dead time (reverse phase column) or disappeared (normal phase column). Is there anybody with any experience on such compounds? Thanks !

[Rafael Chust]

One way of dealing with this stuff is playing with buffers - if your column allows it - frpm pH 2 to pH 11, and see how your analytes reacts.

I assume you are doing RP at low pH, otherwise you should ge retention.

[Patrik Appelblad]

I'd say that your compound should be run under HILIC conditions.
Compounds that elute in the void on RP columns or require addition of IP-reagents are those best suited for HILIC. I would also bet that your compound have a very high interaction with the NP column you tested, which incidently would be the same if you tried a silica HILIC column.
There are though other HILIC phases available, check previous post @ this forum, and our zwitterionic phases might be one suitable alternative.

If you are not familiar with HILIC as technique, a copy of our "HILIC guide" can be ordered via our homepage.

[yangz00g]

HILIC will definitely work. You may also want to try ion exchange.

[SIELC_Tech]

Z.-X. JIANG,

We have a method for DOTA and related compounds on Primesep D column. It is not on the web yet but if you provide us with your email I will send you technical note on DOTA retention/separation.

Regards,

Vlad