Chromatography Forum

Posted: **Mon May 31, 2010 4:00 pm**

Hi there,

acually I am looking for some hints/tip etc for separating three isomeric steroids.
The following things I have already tried: changing the flow rate, changing my gradient, changing the ph-value of the solvents, changing the solvent from ACN to MeOH.
But nothing seams to be successful.

Thank you!

Posted: **Mon May 31, 2010 4:51 pm**

Details, details, details?

What kind of column? What pH? What buffer?

Reversed-phase in inherently not very selective for isomers, so that suggests that the stationary phase chemistry would be more important than anything you can do from the mobile phase. Shorter-chain packings are probably somewhat better than longer-chain (arguably they allow more silanol interaction). Porous graphite apparently can be quite selective for isomers, so that is another possibility.

Posted: **Tue Jun 01, 2010 7:07 am**

Hi,

I am using an UPLC Acquity from Waters,
Column: Acquity UPLC C18
Solvents water and ACN each with formic acid 0.05 %

I have already tried the Phenyl column from waters
it doesn't work better

Thank You.

Posted: **Tue Jun 01, 2010 2:27 pm**

Which steroids?
We have success with a phenomenex LUNA PFP column.