BEH C18 Column high pressure issue
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.My conditions are belowC18 column: uplc BEH C18, 2.1x100mm, 1.7umflow rate: 0.5ml/mingradienttime %A %Bintial 69 314 69 319 40 6010 40 6012 69 31Mobile A: waterMobile B : MethanolI 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!