It seems like there is a frequent change in the pressure when the instrument is in idle condition, without running any samples having an isocratic flow. The column we are using is Poroshell-120, 2.1x150mm,2.7uM and usually at 5% B the back pressure will be usually 254 bar. Please find the attached image showing the HPLC pressure profile. Please provide me with suggestions.
Thanks in advance,
M
Did you purge the system properly? Gas bubbles can cause pressure fluctuations.
Hi there,
as the pressure is decreasing you could have a problem with the degasser not working correctly, or the seals of the pump might need to be cleaned/replaced.
good luck!
Matteo
One possible reason of changes in pressure in your HPLC system could be that presipitates from buffer reagents is building up while your system is idle condition. Check the compatbility of buffer reagents wit the organic solvents (Methanol, Isocnitrile, etc.)
Thank you all for your suggestions !!!
I don't think there is any problem with the pump seal or purging/bubbles etc, because by using other columns that we do have in our lab, yields better results in terms of pressure when the system is in idle condition.
Is it associated with any kind of contaminant clogging either in the guard column/ column itself??
if it is a problem with the column then I would change the guard column and clean the column thoroughly (check its cleaning in place procedure in the column manual).
This is definitely a problem with your instrument, and not the column. Judging from the column, you are using a method with low flow rate (probably 0.2-0.3 ml/min) and also have a low % of organic solvent in the mf. Did you have your hplc optimized for narrow bore columns?
Without more info one can only speculate, but what could be the issue is sticking of the pump check valves, due to precipitates that form in the lines when 100% ACN is used for extended periods of time.
Do you have these variations if you premix the MF so that the pump draws just from one line?
This seems to me a problem of solvents ..and system. you may want to purge the whole system and filter and degas all your solvents before use. If you feel the problem is the column then you can also reverse the column and run it through 100% methanol or Acetonitrile. and then put it back to check the base line ...
and also if the sample sun if fine with other columns, then also you need to monitor the baseline without running samples..
but as what you have attached a picture here this seems a problem of degassing and purging.
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