Chromatography Forum

Hi All,
I am using Agilent 1200 series GPC/SEC. Instrument shutdown after injecting the sample. Error message. Pressure above the set limit (200 bar). While the system is working totally fine before injecting the sample and there is literally no blockages in the system as the pressure is just 15 bar at 1 mL/min flow rate. I already have changes needle and seat capillary. Would be grateful if someone can guide me.
Many thanks

If your system back pressure is: "as the pressure is just 15 bar at 1 mL/min flow rate." then you have the prime purge valve open or no column installed in your HPLC system. Normal operating back-pressure for a conventional HPLC system with std analytical column (4.6 mm ID) is going to be greater than 40 bars just to keep the pump(s) running and stable. Such low pressures would only be encountered when no column was installed or connected to the flow path. Please have someone local with HPLC experience assist you to use the HPLC system.