Chromatography Forum

Hi All,

The pressure in our GPC has gradually increased over the past 4 months. When the latest sample was run, the pressure just got too close to pumps' auto shut-off for comfort and we began trying to repair the system. We checked the pressure drop across all the detectors, replaced the in-line filters in the autosampler, purged the autosampler, purged the needle, replaced the guard column, and replaced the a faulty column. With all this we reduced our pressure by about 50psi, but we are still about 150psi above the total system pressure when we set up the instrument 4 months ago. Any suggestions are greatly appreciated! Thank you.

Since most of the job done , the remaining possible sources for higher pressure are:
Tubings , pulse damper , pump outlet filter ( if any ) , rotor seal , flow cell (s) and waste out tubing.

Step by step , you can localize the problem , first loosen the tubing connection between pump and autosampler , and check the pressure at normal flow .
You may also check the pump pressure with increased flow such as 5ml/min and it must be also reasonable.

Then tighten the connection between pump and autosampler but do not connect the column.
Check pressure , if it is high , possible problem is rotor seal.

Connect a piece of tubing instead of column and check pressure.
If it is high , possible problem is clogged flow cell or waste tubing.

Hi

What system do you have?