Pressure Problem using a 1290 Infinity Binary Pump with a  2.1 x100mm 1.8 micron 600 bar column

Hi:

I am having an increase in pressure when I try to analyze samples on an Agilent 2.1 x 100 mm 1.8 micron column using a starting gradient of A1: 95% H2O w/ 10mmNH4Oac and B1: 5% Acetonitrile w/ 0.1% Acetic Acid.  The gradient increases to 30% Acetonitrile.  The pressure starts out, even on a new column fine, but increases to almost the max column pressure which is 600 bar.  We have run this gradient successfully numerous times using this column.  Even with analyses of blank runs, the pressure may start out low for the first 20 runs, then increases so that it may or may not be able to do all 50 blank runs.  The problem appears to be connected to the column, but I'm not sure if it is the column itself.  We have tried flushing the solvent lines with 100% IPA; without any buffers in water or acetonitrile; changing 0.12 tubing on the entire LC system, but nothing seems to be working.  Any suggestions???

  • Hi fchl235,

    I moved your post to liquid chromatography for better visibility.

    Regards

    James 

  • I don't have any answers, but lots of questions that may help you troubleshoot the problem.   Everything seems to point to some sort of particulates in the mobile phase...

     

    Do you prepare the mobile phases freshly, each time and put in clean bottles?  (How do you prepare the mobile phase?) Can you discount particulates in this mobile phase?  Do you filter mobile phase A?  

     

    What happens if you simply leave the column connected with just starting conditions.  Does the pressure increase with time?

     

    You say that you've run this method successfully numerous times, so what else has changed since it last worked?  Have you started a new container of ammonium acetate, for example?

     

    What are you using to obtain the water for the mobile phases?  If it is a water purifier, are there filters that need to be replaced?

     

    Probably more questions along the same lines...

     

    /Andy

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