Unusual High backpressure with organic solvent?

Hello, it's 2 days my HPLC show strange back pressure in gradient mode when organic % increase, the method is

Zorbax C8

0 min -  1L/min -  40% Metanol / 60 % water  PRESSURE 140 bar

10 min -  1L/min -  40% Metanol / 60 % water  PRESSURE 140 bar

20 min -  1L/min -  90% Metanol / 10 % water  PRESSURE 200 bar

with a mountain signal out of the detector 220nm

This happen also with blank injection

what could happened?

  • Hi

    Without column, it's showing back pressure or not..

  • Hi dmarchini,

    You have to isolate which module is blocked so we can resolve the issue.

    Try removing the column, releasing some connections from the pump, ALS and detector (one at a time) might help identify what is giving unnecessary pressure to the system.


  • Hello,

    On the initial part of the gradient when you get 140 bar, is that normal and expected?  If yes, then you don't have a clog in the system because the pressure would be higher then.  Methanol/water combination has a peculiar pressure profile in that it rises into a "hump" as the percentage of Methanol increases then slowly comes back down.  So it's possible there may not be anything wrong.  You are changing from 40% to 90% Methanol and if you watch the pressure profile, you are going to see that slow increase then decrease over time.

  • Did you get a solution to this?

    The pressure profile looks backwards to me.  Maybe a crazy question, but did you get the bottles the wrong way around?  I'd expect 40% methanol in water to be more viscous than 90% methanol in water.


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