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- Posts: 4
- Joined: Tue Mar 10, 2020 1:03 pm
I first experienced the problem a week ago. The pressure on the instrument when flowing 1mL/min of Methanol is typically around 1100-1200. When the problem originally occurred, I noticed the pressure of flowing 1mL/min of Methanol was down to ~850psi. I checked all connections of the HPLC and have not found any leaks. I then removed the column and tested the pump at 2mL/min for 20 minutes. I collected the eluent and at 20 minutes the amount was almost spot on at 40mL. I then reconnected the column. After injecting a few samples the retention time of my PCMX peak was extending further and further out. Initially the retention time was around 4.8 minutes and continued to extend out (5.1min, 5.25min, 5.75min, 17min).
Even though the pump test without the column was successful, I figured there might still be an issue with the pump head. I removed the pump head and replaced the consumables within it (seals, back-up seals, and o-ring). I reconnected the pump head and attempted to flow 1mL/min of methanol through the system. The pressure was back up to 1200psi and was holding consistent. I figured the system might be fixed and started to shoot samples again. I tried to calibrate the instrument 4 or 5 times across 2 days. The calibration never came out great; however, the retention time for the PCMX peak was very consistent. The next calibration I tried, was not as successful. The PCMX peak began to shift later once again. I pushed 1mL/min of methanol through the system again and the pressure was back down to 860psi.
I figured I had deduced that the problem was the pump head, since removing it and rreplacing the consumables seemed to have resolved the issues for ~12 hours of operation; however, I was a bit baffled when the problem reemerged.
I have replaced the consumables in the mixer and I have replaced the inline filter that is after the mixer, but before the injection valve. Nothing has seemed to have helped.
Yesterday I took off the cover on the detector and did notice a bit of salt buildup surrounding the connection to the outlet port of the flowcell. My next thought is to try to clean/replace the flowcell. I have not gone down this path yet, because I'm not quite sure how a flowcell would cause the issues that I'm experiencing.
Does anyone have an idea as to what might be wrong with my instrument?