thienopyridines

[Ivo]

Hi to everyone

I am working on thienopyridine class of substance and have some problem with selectivity of two. I am using C18 100x2.1, 1,8 um but I am wondering is there any better choice for thienopyridines... I was thinking of Phenyl-Hexyl or Fluoro-Phenyl phase column. Any suggestions?

Thanks
Regards,
Ivan

[schlepro]

Dear Ivan,

Without a little more information, all I can say is check the column catalogs/lit. The structures look like something that could run just fine on a C18, and you'll probably need acid (e.g. 0.1% TFA) in your aqueous channel in order to get Prasugrel to resolve. My experience is that there is nothing sacred about ones stationary phase, so I doubt you will gain much from using a phenyl-hexyl column or similar. Can you provide more about your run conditions (H/U plc, mobile phase, gradient, temperature, flow)? Which compounds are coeluting? Do you need the method to work with, say Cysteine as well?

Sincerely,
Keith

[Ivo]

Dear Keith,

Thank you very much for replay. I was out of lab over holidays so I reposted with some delay... btw, have a successful new year... with lots of fun, of course

I am working on Ticlopidine, 5-(2-Chlorobenzyl)-4,5,6,7-tetrahydrothienol[3,2-c]pyridine. It nearly coelut with similar impuriti.. only difference is sulfur position in thienopyridine ring (---tetrahydrothienol[2,3-c]pyridine). Second imp. wich I would like to separate more is N-(2-chlorobenzyl)-2-(thiophen-2-yl)ethanamine (basically ticlopidine with open N-ring). Run conditions are: UPLC; mob A (Na-pentansulfonate, monohydrate buffer), ph 3.4 with H3PO4; mob B (100% MeOH); gradient (initial 30%A-70%B, 10 min 70%A-30%B, 11 min 30%A-70%B, 13 min 30%A-70%B); flow 0.5 ml/min; temp: 45 cels/deg; 220 nm.
I have tried different mobile phases and gradients and I find this most satisfactory, though, I will appreciate any comments regarding those conditions or any other. I was thinking about phenyl columns because all analytes contains some kind of ring and according to catalogs have some advance over C18.

Sincerely,
Ivan

[Vlad Orlovsky]

Since all your compounds are ionic and hydrophobic, your best bet for separation is mixed-mode. Here is how mixed-mode can be used for separation of isomers:
http://www.sielc.com/Compound-O-Toluidine.html
http://www.sielc.com/Compound-4-Aminosa ... -Acid.html
http://www.sielc.com/Compound-3-5-Dihyd ... -Acid.html

Contact me if you have questions.

[Ivo]

Vlad, thank you very much for replay and info.
I´d feel free to contact you for more questions.

Sincerely,
Ivan