I'm performing peak purity at 220nm and upon processing I am finding that my main peak is not spectrally pure. I don't believe this is a true result since in the past the peak has been analyzed as pure. I believe this may be because my solvent angle is not accurately represented and/or the solvent interference is problematic.

I'm interested in 1) utilizing 3D Blank Subtraction, or 2) manually calculating my solvent angle.

My questions are this:
1) Would 3D blank subtration be useful for peak purity assessments? If so, can someone point me in the direction of instructions for how to use this field? I can't find specific instruction.

2)I am using a non-corresponding standard (1% relative to the nominal concentration), so taking the maximum solvent angle from replicate injections of the standard is not useful. B/c the peak is so small, the retention time is slightly different-shifted away from a baseline disturbance at the retention time of the main peak. Too at the nominal concentration, the main peak is not "pure". Are there other ways to determine an appropriate solvent angle? If so, please point me in the right direction.

thanks so much!

Melissa