tailing of sugar compounds

[hajdaei]

We all know that amine containing compounds are the classic compounds which show tailing on reversed phase HPLC columns. But right now I am running compounds that contain a lot of OH groups. Specifically arbutin and Kojic Acid. It is not clear to me why these compounds should be tailing, but they are...even with 0.1% phosphoric acid in the mobile phase (and we've tried 2 different columns).

Any ideas

[tom jupille]

Assuming you have ruled out "physical" causes (e.g., strong diluent; large injection volume, extra-column effects, etc.), all that is required for tailing is that you have a reasonably low population of "active sites" which retain your analyte strongly. In the case of amines, active silanols are the usual suspect.

Both of these compounds look like they would chelate residual metal ions on the stationary phase surface. As a first guess, I would expect them to tail more on older, "type A" packings (which presumably have a lot of residual metal cations) and less on newer, "type B" packings, which are based on higher purity silica.

Based on that hypothesis, maybe adding something like EDTA to the mobile phase will help.

Just out of curiosity, what columns did you try?

[hajdaei]

We tried a C30 (YMC carotenoid) column and thermo hypersil C18 AQ