Retention time shift on an Agilent HPLC system was reported during routine runs, affecting method consistency and data reliability. Initial flushing revealed abnormally high back pressure even with the purge valve open, pointing to a restriction within the pump.
Diagnostics confirmed a clogged PTFE frit inside the pump as the root cause of the pressure issue. After replacing the frit, system pressure returned to normal levels. A follow-up leak test initially failed, which led to further inspection of recent maintenance performed on the system. The inlet and outlet check valves had not been properly tightened, and once corrected, the leak test passed successfully.
Additional evaluation included a gradient test to assess overall system performance. The system completed all checks without errors, and the switching valve was verified to be functioning correctly. After service, the HPLC system returned to stable operation with consistent retention times.
