A sequence of 15 samples (ID: LIR-20251123-A) was being run for the quantitative analysis of [Specify Compound/Analyte] in [Specify Matrix, e.g., pharmaceutical tablet, environmental water sample]. The sequence included standards, blanks, and quality control (QC) samples.
Point of Interruption: The interruption occurred during the analysis of the 7th sample (ID: LIR-20251123-A-07), approximately 3 hours into the run.
Observation: The instrument’s software reported a “System Suitable Failure” message, immediately followed by the sequence stopping. The solvent flow dropped to 0.000 mL/min.
🛠️ Immediate Actions Taken
The analyst immediately attempted to check the software error log and instrument status.
Verified that the solvent levels were adequate (A, B, C, and D channels all above 50%).
Checked for any visible leaks at the pump heads, injector, or detector—none were observed.
The system was placed into “Standby” mode to preserve column integrity and prevent pressure build-up/damage upon restart.
Notified the laboratory supervisor, [Insert Supervisor Name].
🔬 Investigation and Root Cause
Software Log Analysis: The primary error message indicated a “Pump Head Pressure Low Limit Exceeded” just before the System Suitable Failure flag. The pressure trace showed an instantaneous drop from P \approx 1200 psi to P \approx 0 psi.
Hardware Inspection: A physical inspection revealed that the main power cord to the HPLC stack (specifically the pump module) had been partially dislodged from the wall socket.
Root Cause: The power interruption to the pump caused an immediate loss of solvent flow, leading to the rapid pressure drop and subsequent triggering of the “System Suitable Failure” safety protocol, which halts the sequence. The initial pressure drop was the true precursor, and the System Suitable warning was the result of the system not being able to achieve the required pressure/flow parameters.
✅ Corrective Actions
The power cord was securely reseated in the wall socket.
The HPLC pump was restarted and allowed to prime for 30 minutes to ensure a stable baseline and removal of any potential air bubbles.
A System Suitability Test (SST) was run using a fresh standard to verify instrument performance (checked parameters: Tailing Factor \leq 1.5, theoretical plates N \geq 5000). The SST passed.
The entire sequence (LIR-20251123-A) was re-run from the beginning with fresh sample preparations where stability was a concern (or restarted from sample 1, if stability was confirmed).
⚙️ Preventative Actions
Labeling: All critical instrument power cords and sockets (especially for HPLC and GC) will be marked with “Do Not Unplug – Critical Instrument” labels.
Cable Management: Cable ties/straps will be used to secure critical power and communication cables, minimizing the risk of accidental disconnection.
SOP Review: A reinforcement training session on checking instrument cable connections and general system pre-run checks will be scheduled for all analytical personnel.
Signature of Analyst: _________________________
Signature of Supervisor: _________________________
