gradient sloping downwards

[shadow]

Hi and thanks in advance for helping out.
I am using acetic acid adjusted to pH 5 with ammonium hydroxide on A and 100% MeOH on B and I am monitoring at 230nm using a phenyl column. My problem is that the baseline slopes downward and I would like to correct for it and don't know how, any help would be appreciated.

[seamoro]

your going to get slope when using a gradient you really cant help that. . You could try to raise your wavelenght higher to a region where there is less absorption but you may lose sensitivity or you could go isocratic

[danko]

Hi Shadow,

Acetate and 230 nm detection is a bad combination. Use another acid/salt instead of acetic acid/acetate.
What is the pH in you mobile phase by the way?

Best Regards