GPC Agilent 1200/1100 system - baseline issues


Our system consists of the following components and stacked like that from top to bottom:

  • Tray with THF Bottle as solvent A/no solvent B and Waters in Line Degasser
  • 1200 Series G1312A Binary Pump
  • 1100 Series G1313A Autosampler
  • 1100Series G1316A Column Compartment with guard column and analytical column in sequence
  • 1200 Series G1362A RI Detector

I am assessing the instrument as it has been sitting for a long time and was not in use.

When I run the system as it is set up with a flow of 1 ml/min and temperature of columns and RI at 55C, this is what I see:

When I change the flow to 2 mL/min the freqency observed of the rhythmically varying baseline does not change (approximately 13 s-1). From what I understand is that that behavior is not caused by the pump as if it was that frequency would change proportionally with the flow.

If I bypass the degasser using degassed THF, this is what I see:

To me that means that the wavy part of the noise came from the degasser, but there still is noise in the system.

After purging RID reference cell (did not know I had to do this as I am just learning about GPC) and changing the T to 35C (to not be at the limit of the temperature range for RID in case that matters). 

After equilibration over night, this is what I see:

I then bypassed sample port and column

It seems that there is quite a lot of noise still. Do I need to purge the system in a certain way in case there are bubbles, etc? Any feedback is welcome on how to further assess and optimize.

Best, Bettina

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