Why back pressure increases 100%MeOH mobile phase

[montana]

I have experienced that when I run on HPLC for several days that the back-pressure increases (4300 PSI) with 100% methanol as mobile phase and flow 1ml/min . I analyze serum samples ( Deproteinization with methanol)
What is the reason for that? and what is the solution
Thank you

[Vlad Orlovsky]

if you are using silica column, there is a chance that you solubilize silica or "rip off" tiny particles of silica, thye travel to filter in the column and plug it.

[montana]

if you are using silica column, there is a chance that you solubilize silica or "rip off" tiny particles of silica, thye travel to filter in the column and plug it.

I am using C18 column,so what is the solution that you suggest.

[Vlad Orlovsky]

look at other brands, don't leave column in MeOH overnight, get away from MeOH (by using EtOH, for example), flip column from time to time, replace filter on the column (not a trivial task for many columns), redevelop method with ACN.

[montana]

Thank you very much Vlad Orlovsky.

[tom jupille]

And you may still have residual protein in there (MeOH does not remove 100%).