Chromatography Forum

Hi,

I am new to HPLC and have a question. We have an Agilent 1100 HPLC and are running Chemstation for LC 3D, Rev A.08.01 [783].
While running the sample and watching the online plot, I continue to miss seeing peaks of interest even though the X axis is zoomed in to the point I am seeing a second or two at a time. When I complete the run and view the spectra at the end, there are peaks that show up that aren't there during the online plot view. Can anyone advise me as to what I may be doing wrong? Thank you.

You need to double check that the online view is showing the correct trace, if you have multiple UV windows stored it is very easy to select a different one for the on-line and processing pages. Check what the method is set up to display for the on-line view (it's the window where you can overlay such things as pressure or solvent gradient)

I only use the Online Plot as a rough "guide".

Hi,

Thank you for the suggestion. We are having to use the online plot to look for a particular fraction we are interested in, and when we see the peak on the online plot, we have five seconds to manually begin collecting the fraction. So in this case I need to be able to see what is happening in real time so that I can collect the sample.

Chris

Thank you so much to everyone who helped! This fixed the problem and what I see happening in the online plot window looks like what I am seeing when I print the final result.