The Problem
An Agilent HPLC system was showing retention time shift during routine runs. This type of instability can affect method consistency, peak identification, and data reliability, so the investigation focused on both pressure behavior and pump performance.
Diagnostics
Initial flushing showed abnormally high back pressure even with the purge valve open. That result pointed to a restriction inside the pump rather than a downstream column or method issue. Further inspection confirmed that a PTFE frit inside the pump was clogged.
Repair
The clogged PTFE frit was replaced, and system pressure returned to normal. A follow-up leak test initially failed, so the service review continued into recently maintained pump components.
The inlet and outlet check valves were found not fully tightened. After the valves were corrected, the leak test passed successfully.
Performance Verification
ScientifiCo performed additional testing to confirm that the system was ready for analytical work. A gradient test was completed to evaluate overall system behavior, and the switching valve was verified for proper function.
Result
The HPLC completed all checks without errors. Back pressure normalized, the leak test passed, and the system returned to stable operation with consistent retention times.
