BEH C18 Column high pressure issue

<p> Ive had  a high pressure issue for over 2 months now with this method im using (waters explosive method). Ive tryed everything and the problem still isnt resolved! I suspect its particles clogging the column from the mobile phase even though i buy 0.2um filtered mobile phase i also filter the mobile phase inhouse and have a guard column and the column still clogs up. We have gone through 3 columns now and the same issue occurs. My filtering technique is good and i have also used a wide range of filters with not much sucess (filters recommended by waters). I have used 0.2um RC,GHP, PTFE and the same pressure still occurs which i find ridiclous. I have had also waters technican pull apart the UPLC and do a full PM but the pressure issue still continues. All my solvents are hplc grade or better. The glass wear i use has only ever been used for this purpose only (uplc). Yesterday i tryed a new column again and same thing happened. I filtered the Methanol with PTFE and it all apeared good when running 100% through the column then i added the water in a gradient (intial gradient of method is 69:31 water/methanol) and the pressure rose from 5000psi to 10000psi and stayed stable for 1 hour and then the pressure starts to rise again!.I stop the flow and start the flow again and i cant even get 0.100ml/min without a psi of 8000psi! I backed flushed the column today and put the column back on the system and managed to get improvement with a psi of 13500psi at my expected flow rate of 0.5ml/min so thats not bad....but its slowly building again very slowly.</p><p>My conditions are below</p><p>C18 column: uplc BEH C18, 2.1x100mm, 1.7um</p><p>flow rate: 0.5ml/min</p><p>gradient</p><p>time   %A   %B</p><p>intial  69    31</p><p>4      69     31</p><p>9      40     60</p><p>10    40     60</p><p>12    69     31</p><p></p><p>Mobile A: water</p><p>Mobile B : Methanol</p><p>I have also used a variety of suppliers of my solvents. Im about to give up on this cause i cant see anywhere else i can improve or change!...any advice!</p>


  • Hi Seamus,

    I'm not clear if you saw this pressure rise without doing a sample injection or if you injected your sample and then ran the gradient.  If you have injected a sample then I would suspect that it is your sample that is causing the clogging.  If not then something in your mobile phase (as you have said) or something in the plumbing for the A line is causing the problem.  Do you add anything to your water?  Have you changed the solvent filters?  Did the engineer replace seals etc. or not?  These are things I would check but you may already have done them.  Good luck.  Please report back.

  • I believe it was the filters i was using. Today i didnt filter and removed the inlet frit in the column inlet and had a perfect run there after...fingers crossed it is!

  • atus

    You can try to install an inline particle filter between the injector and the column. I have installed one on my UPLC. I also put an inline particle filter in the fitting before every guard cartridge and column. It is much cheaper to replace the particle filter. Besides Waters inline guard cartridge, you can look into Optimize Technologies, or Analytical Sales & Products Inc for more user-friendly equivalent .

    You may still want to protect the pump with solvent titanium filter, and consider replacing the solvent filters more frequently or clean them by sonication.

    Good luck.