Chromatography Forum

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

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.

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.