high delta

Dear all,I have some problems with my system pressure and I don't know the reason. I have a very high delta pressure. My conditions: flow=0.05 mL/min, A1=ACN100%, B2=ACN70%, A1/B2=50/50, system pressure=3608psi, delta=589 (see attach). Column ACQUITY UPLC BEH C18 1.7 um, 2.1x150 mm and guard column C18 1.7um. Thank you.


  • Hello

    First, you need toestablish where the pressure is coming from, starting at the waste line from the outlest of the detector break that connection and see if that causese the pressure drop. Reconnect and do the same for each piece. I do suspect the column or the guard, but it is possible that you have a clog.

    After this please let us know. Then we can proceed from there.


  • look like 5 broad peaks, its simple you 1st prime the pump with 10% MeOH & observe primary A&B from Sample Manager,... & also A&B outlet (you can see solvent coming steadily)...if priming OK,means problem outside the BSM region... disconnect column & vanguard from column inlet & set flow rate high...so that you can see stable pressure..... if still high pressure ups&down....i suspect your BSM mixer (near A&B outlet) is clogged....to confirm, open BSM mixer outlet,,, & again set flow to observe pressure.....if mixer clogged pressure never stable

    i also see you have TUV communication failure in your UPLC picture....... but ithink your guard column is clogged....

    --- Salman

  • hallo,

    after I post the message I did exactly the steps that you told me to do and I found out a 5500psi pressure on my guard, so I have changed and now it's ok.

    thank you.


  • hallo,

    you are right. it was the guard (I had ~5500psi pressure on guard) so I've changed it and now everything it's ok.

    thank you,


  • Valantina

    Please monitor the time before the guard goes high pressure again. Maybe keep track of the pressure once a day or so on this column.

    While the purpose of the guard is to protect the column, this may be a one time blockage, but it may be that the quality of your solvents or additional sample prep may be necessary to limit the reoccurance.

    Hope all goes well,


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