Chromatography Forum

Hi all,

I have a big problem with separation of phenolic acid on Poroshel 120 SB-C18 column.

I am trying to divide some phenolics on this column , but the more of them have the same RT. For example, p-cumaric acid, rutin, catechin, caffeec acid appear at 36,7 min. The Mobile phase that I use is A: 0.5 % acetic acid , B: AcN in gradient condition - the first 15 min 20%B, to 40th minute 80%B , to 50 min. 100% B and at 50 min 20%B.

What I should to do ?

Thank you!

There are only 6 ways to change selectivity in reversed-phase:
1. Mobile phase strength (gradient steepness)
2. Temperature
3. Organic solvent type
4. pH
5. Additives
6. Column chemistry.

It's a matter of a day to try each of them (make a big change and see if selectivity changes; if it does, then you can optimize).

Hi,

Perhaps you can try a different HPLC column. Imtakt has a new multi-mode column which has anion, cation, and reverse phase ligands on the stationary phase. This column will definitely give you different selectivity. We have an application for phenolic acids/organic acids using our Scherzo SM-C18 column. The link to the application is below:

http://www.imtaktusa.com/site_media/fil ... TI649E.pdf

More information about the Scherzo family of columns is below:

http://www.imtaktusa.com/site_media/fil ... family.pdf

If you would like any more information, feel free to email me at bverma@imtaktusa.com.

Hope this helps!