Chromatography Forum

I was setting up a method for some b vitamin samples and while running a standard I went over pressure. I was using an Agilent advanced bio peptide plus column 2.7 100A
I realize its not ideal for vitamins but its what I had installed. While out of the room the instrument went over pressure. When i tried turning pump back on it immediately went over pressure again. Using an Agilent 1100, binary pumpi G1312A


1st I removed column and left guard column on. pressure was ~50 at 1ml/min

2nd i tried column only and pressure rose quickly. I tried back flushing at starting at 0.1 ml/min and worked up to 0.5ml /min, pressure went to 400.

3rd removed column and opened purge valve, pressure did not go down. Pressure is now going down about 1 bar per minute. I removed purge valve to check gold seal and it looked new, was just recently replaced. With purge valve removed pressure did not go down.

4th I removed the line running from pump to autosampler, pressure didnt change. pressure is at 388 at this point with pump not running. I turn on pump set at 0.1ml/min 100%MeCN within 2 seconds shuts off at 418 bar. Is decreasing at about 1 bar/min.

5th shut down instrument, shut down chemstation, power cycle. No change.

Blockage seems to be somewhere in pump, but not sure what to look at next. Any ideas?

Update i loosened the capillary going into the bottom of the damper and I heard a hiss and sprayed in the face with solvent(lab glasses were on) pressure went to zero.

After releasing pressure I set the pump to 0.1ml/min and it slowly crept up to 385 and rising when I shut the pump off.

I then disconnected the capillary that runs to the bottom of damper at the "T" split. Pump runs and pressure does not go up. Does this mean I need to replace the damper?

You may also loosen the other capillary connection of damper , in order to locate the blockage.

If the pressure drops , damper is ok.

Then you may proceed to check the capillary tubing .

Can you set up to backflush the damper with low flow rate of solvent-only to waste?

That's how I would also flush a heater core in a vehicle !!

While running at 0.5 I loosened the other line on the damper and pressure went down. I also tried disconnecting at both sides of the solvent mixer one at a time and pressure went down each time. With pressure built I have disconnected each spot that is highlighted in the image and the pressure has gone down. The capillary from the pump to the autosampler was loosened individually at both connections, pressure did not change. Any new thoughts?


https://i.imgur.com/YmJ9ndb.jpeg

i missed a connection. coming off the mixer it connects to a block that the purge valve is attached to. i dont have a luer lock adaptor for a syringe but i tried to push solvent through it and had no luck. I think it may be the issue. Any idea of a part number for that little bent tube? or thoughts on how to unclog it. Sonicating it now in MeOH.

When I was working, I would just make my own tube from either stainless steel tubing or plastic HPLC tubing, and nuts/ferrules. I cannot imagine trying to do HPLC without such routine parts around.

I just wasn't sure what the internal diameter was. I ended up making something from some tubing I had lying around. Ran a few standards and all the retention times have stayed the same so I think i'm good to go now.

i missed a connection. coming off the mixer it connects to a block that the purge valve is attached to. i dont have a luer lock adaptor for a syringe but i tried to push solvent through it and had no luck. I think it may be the issue. Any idea of a part number for that little bent tube? or thoughts on how to unclog it. Sonicating it now in MeOH.

Sonication with back-pressure applied is probably your best best.