Chromatography Forum

Guys hope every one having a good day. HP 1090, Chemstation, manual injection, three solvents delivery system, 70:30 methanol:water mobile phase. I have high pressure around 80 bar than other HPLC Agilent 1100. Also, every thing else working perfectly without any fluctuation in the flow rate or the pressure. The pressure after the syringe pump is 4 bar, after the inline filter is 6 after the injector is 8 bar, before the column is 10 bar, after the column is 200 and with the column is around 262 (it should be 182). Any help will be appreciated. Faris

First thing I would do is pump the column in reverse. You may have particulates deposited on the frit at the inlet. Let it pump that way for a while, at least 2 column volumes, then try turning it back around. If the pressure does not come down, you could flush the column with a series of solvents varying in polarity. That would remove particulates that may have gotten past the frit and settled on the packing or perhaps particulates that have fallen out of solution partway through the column or been absorbed for other reasons.