Enalapril UPLC

[kalko]

Hi All!
Does anybody have an experience with Enalapril onto UPLC? I have a problem with it, because I detect it like a saddle when I try to transfer HPLC method to UPLC. (Just to remind, Enalapril peak is a pretty wide peak on HPLC, with Tailing about 1.6.)
I am assuming that I am dealing with diastereoisomers or something like that.
Please help!

Milosh

[Uwe Neue]

There are many post on the subject. Enalapril has two conformers that rotate around the nitrogen in the proline group. They can give separated peaks with a step in between. One can fix this by speeding up the equilibrium, either at lower pH or at higher temperature or both.

[Bryan Evans]

I'm curious as to whether the phenyl phase might be better for this
type of application (as opposed to the C18 phase).

If for example, one used Unison UK-Phenyl with ACN (as opposed to
MeOH) - one should get less selectivity (since the pi-pi interaction
on phenyl group can be masked using ACN).

Below is an example of branched chained alkylbenzenesulfonates
on Cadenza CD-C18 and Unison UK-PhenyL
http://www.silvertonesciences.com/files/TI300E.pdf
http://www.silvertonesciences.com/files/TI301E.pdf

Molecular recognition and steric selectivity are better on the ODS phase
than compared with the phenyl phase. Perhaps the conformers could co-elute on the phenyl phase
(as opposed to being separated on ODS phase).

It's just a thought - but maybe it's worth a try.