controlling retention time and pH

[Douglas Moore]

Sluggo, the retention time behavior may be a function of the compound pKa. If the mobile phase pH is close to the pKa of the compound you are analyzing, small changes in pH can have dramatic influence on selectivity and retention time. Do you know what the pKa of your compound is?

[vincenzoxxx]

i've never observed this kind of variation with 0.05 change of pH scale
i suggest this:
Since i think your compound is completely protoned at 2.4
the error is in my opinion the second readjust of pH, i never do it or see it done.
tea can be useful but there are a lot of vendor who sells column with good perfrormances solving the tailing problem without using tea (you may try a column with a high surface area like symmetry or synergi playing with the strong solvent in case of too much long retention times).
vincenzo

[sluggo]

It now looks like the issue was due to high sensitivity to organic %.

I am now using a different method for this compound.

thanks