My peaks disappeared

[dw237606]

I’ve only been doing HPLC (the reverse phase style) for a few weeks now, so please bear with me and talk to me like a child. I’ve been having some difficulties this week with respect to not getting “peaksâ€

[Schmitty]

What is the "new" detector make and model? Perhaps you only have the UV lamp turned on, and not the VIS lamp, so as not to be able to go to the longer wavelengths? Check for leaks!

Good luck!

[HW Mueller]

One always looks at the point where problems started to get at the cause, in your case it seems obvious: the methanol is too strong a solvent for the sampe, it "washes in" the analytes, or at least part of them, giving these broad peaks. There are a lot of mentions of sample solvent incompatibilities (with the mobile phase) in this forum.