peak shape problem!!

[Uwe Neue]

I don't get why one would want to use an ion-pair reagent for the chromatography of astragalosides. There are no ionic functions in this thing. Maybe such additives would be useful for an enhanced MS response, but TFA does not strike me as the best choice for this purpose either.

[Bruce Hamilton]

Agilent offers a Compendium of HPLC methods for Traditional Chinese medicines ( downloadable from their site or as CD 5989-6595EN ),

That uses a Zorbax Extend C18 column with 65:35 H2O:CH3CN, and a WWW search of " astragaloside iv HPLC " reveals similar simple mobile phase systems, some with buffers.

Maybe your peak shape is caused by other issues, such as column choice.

Bruce Hamilton

[jonathonswq]

thank to bruce and uwe!
i was confused by TFA, because i don't think astragaloside iv need ion pairing agent either.
then i'll find the information from agilent.
thanks!