Perfectly Consistent baseline dips in PDA of Waters H-Class
Posted: Mon Apr 27, 2020 8:54 pm
by MissRedHead19
Hello Experts! I am seeing consistent negative baseline nips every 10 minutes in my PDA on a Waters H-class UPLC. I can provide images of the dips in the blank injection, though I have been unable to figure out how to add it to this post (new here, sorry!) I am looking for insight as to what the issue may be/what I could do to fix this. I have a ticket into my workplace's metrology, but I am looking for a faster solution/and insight from any experts here in the meantime (as there will be a delay until they are able to take a look I am sure.)
Re: Perfectly Consistent baseline dips in PDA of Waters H-Class
Posted: Tue Apr 28, 2020 1:05 pm
by Multidimensional
Please define "dip" in scientific terms. Using units, please tell us how far the "dip" drops, relative to the baseline and at exactly what wavelength and bandwidth you are monitoring PLUS teh exact mobile phase composition and flow rate used. These are critical, basic parameters that need to be described before any useful advice can be provided for free.
Let's start with the basics:
The source / cause must be identified before the solution can be proposed.
Start by changing the flow rate to either 2x or 1/2 the regular rate (NOTE: Only do this if it is safe for your column, HPLC system and method!). Allow time for re-equilibration. Look at the baseline. Did the negative "dip" change in period? If so, please describe in terms of peak width and time.