Chromatography Forum

Morning Everyone,

I am currently using an Agilent 1260 binary pump with a 10mm, 1uL flow cell with a max pressure of 60 bar. Part of my everyday analysis includes looking at different acrylic resins, which means i'm injecting these resins into my system on a consistent basis. The issue that I'm having is that my flow cell is constantly getting clogged resulting in a massive increase in pressure throughout the entire system and run during analysis. I do not want to spend $3k to replace the flow cell so what is the best option to clean it and reduce the pressure?

please help

I assume that you've isolated the pressure build up to the flow cell and not build-up at the head of the column or guard column.

Typically one would find what the sample is very soluble in, then pump that through the flow cell at a slow rate to keep the pressure below the cell maximum. Maybe try a reverse flush too.

I'd be curious if you ran the same sequence without injecting or just injecting blank solvent if the same pressure build up would occur. Because I'd "guess" that it would take a while to deposit crud on a flow cell.

Correct I have isolated it to the flow cell.

Acetone seems to work pretty well. I do not have HPLC grade Acetone on hand currently but I am tempted to use it anyways specifically for this purpose of cleaning. Would there be any adverse effects on the rest of the system by not using an HPLC grade/purity solvent?

I'm not sure what you mean by your last statement? Do you think this is something related to the mobile phase for the run and not the samples I am injecting?

Is it possible that the acrylic resins react under UV irradiation and build a polymer plug in the flowcell, or in the outlet tubing part? You should notice this not only in the pressure rise, but also in decreased sensitivity or increased noise in the chromatogram.
I would not reverse flush the cell: If the plug is in the outlet tube, you will push it into the flow cell and the problem will be back soon. If forward flushing does not help, open the flow cell and then flush from both directions. A plug would come out then.

Good luck
Jörg

I do not have HPLC grade Acetone on hand currently but I am tempted to use it anyways specifically for this purpose of cleaning. Would there be any adverse effects on the rest of the system by not using an HPLC grade/purity solvent?

Filter the acetone first through a 0.45 micron membrane.

Be careful running pure Acetone with your LC pump.. If the seals are not up to it they might start degrading.. Many pumps have special Normal Phase seals.

Personally I would flush the flow cell with Acetone (if that is would you have found that acetone works) manually with a syringe.. and preferably in reverse to avoid pushing the clog further into the cell.

We use an old Shimadzu system for this purpose:cleaning flowcells, capilaries, valves and such.We do this because we learned the hardway what it means to clean a stubborn part "online" so to speak.We have all kind of mechanical adaptations so we pretty much cover all the major parts manufacturers.So, if in doubt, my advice is to clean a part "offline".