Chromatography Forum

Dear Forum,

I am getting erratic pressure on Waters UPLC which also cause peak split and RT shift in the middle of run. After few injections like this, the pressure comes back to normal. Please see


https://drive.google.com/open?id=0B4Mjb ... JYelpfVWc0

Any idea? The technician have checked the inline degasser, replaced check valve but the issue still persist. What do you think?

Thank you,
Pratheep

You did not include ANY HPLC info (flow rate, mobile phase, column, detector, scales????) so difficult to provide answers which apply to your situation.

In general, the pressure plot (with no scales shown) may imply that the piston seal(s) are worn out. Have you performed a proper pressure test of the pump to confirm correct operation? If the pump is mixing solutions, have you verified correct metering at each channel and mixing??? Have you checked for pump cavitation (again, no information provided about what you are doing).

Is there someone there with some practical HPLC experience whom can help you? This should be very easy to troubleshoot.