mobile phase, HPLC

[sophieUMB]

May I use more aqueous phase than organic phase for reverse phase HPLC column, such as C18 column?
like 60% aqueous phase, 40% organic phase?


I am an newer for HPLC. Hope it is not silly question.

Thanks,
Sophie

[Consumer Products Guy]

May I use more aqueous phase than organic phase for reverse phase HPLC column, such as C18 column?
like 60% aqueous phase, 40% organic phase? I am an newer for HPLC. Hope it is not silly question.
Thanks, Sophie

Yes. We go low organic-high aqueous frequently as starting point for gradient elutions for polar species.

There are some C18 columns that cannot well tolerate less than 5% organic, so to go that low, check with supplier.

[Gerhard Kratz]

For a standard RP column I would recommend to follow the 5% rule. Keep always minimum 5% aqueous phase or on the other side 5% organic phase.