I am using shimadzu make hplc system, in this system am using mobile as ( acetonitrile and water 80-20) the pump pressure not stable it will goes up and down, also change the grad column filter, still this problem occur. What can I do for this ?
Are you performing a gradient analysis? If pressure changes follow the gradient, then this may be normal, depending on the individual solvent viscosities.
Are the pump heads functioning correctly? Refer to the pump maintenance
manual
Are all the solvents degassed? Place the mobile phase reservoir in an ultrasonic bath to remove dissolved gases. Sonicate as well the suction filters for some min by dissolving them in IPA.
Purge the individual pump line with your mobile phase for 10-15 min. During purging make sure that purging is happening, pull the mobile phase carrying tube from the reservoir for a while and create an artificial bubbles in the channel that will show you purging is really happening.
We really need to have more precisions on your troubles to answer you. What kind of bump ? like 80 to 100 or 80 to 82 bar ? What about your flow, he is stable ? All the parts of the chromato. can provoque that kind of troubles, the pressure isn't a parameter just a consequence. I'm waiting for precisions.