Chromatography Forum

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

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

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

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.

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

Sincerely,
Ivan