Chromatography Forum

Hi Guys,

I have been using Agilent 1200 series UPLC with quaternery pump for regular analysis.Of late I have noticed that for isocratic 60/40 methanol:water with flow rate of 1mL/min, the pressure goes as high as 400 bar. I use a Zorbax XDB column.The peak shape looks normal (no column fouling)

Can you let me know how I can figure out if the problem is because of column or the pump?

Thanks in advance

What particle size, column dimensions, & flow rate?
Has the pressure always run this high or has it increased?
If it has increased, was it gradual or abrupt?

If you have small particles and a long and/or narrow column, that pressure might be normal. If the pressure has increased substantially, the easiest test is to swap in a new column. If the pressure stays abnormally high, it's the pump.

Additionally would be good to know what pressure of the mobile phase is without column (there might be problem with pump pressure sensor) and without any flow (is it 0?).

Could be some particles present in the injected sample solution? Something that could "stick" to the column (some polymers?)? When not in use is column stored in the same solvent or other composition is used? Presumably column is not used for other tasks?

If you still get high pressure without column as first check the solvent filters.
You can also check the ptfe frit located in purge valve (if your pump model have it).