Agilent 1100 quaternary pump ripple issue

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14 posts Page 1 of 1
Hopefully someone can point out what I'm missing here. We started experiencing a persistent ripple of > 1% with out standard method. Rather than go into the details of the method, here's what I've done so far: replace line filter, replace PTFE frit filter, replace pump seals, replace active inlet check valve, swap outlet check valve from another system. The ripple of > 1% persists even if I completely bypass the mixer (solvent line directly to pump inlet) pumping 100% IPA. The degasser is a Systec 4 channel with all lights green and it appears to be working well. Running the Agilent Tools leak test, it fails with the slope of all plateaus being negative. I swapped the entire pump head from another 1100, and surprisingly the ripple is still 1-1.5%. The only thing left in the troubleshooting guide is a leaking pulse dampener, since if that's the cause, swapping the pump head wouldn't solve the issue. But in all my years of doing HPLC, I've never seen that be a problem. Any tips or suggestions here would be greatly appreciated, since other than swapping the dampener, which is a bit of a chore, I can't think of what else to do.
It looks like you've done many of the logical steps.

If it was my system, I would de-gas the IPA the old fashioned way (vacuum-filter through 0.45 micron membrane) and temporarily route the IPA directly into the pump, and see how the test goes.
could it be a misconfigured solvent compression setting?
Did you calibrate your solvent with that special "calibration tubing"?

(I don't have much experience with Agilent. Just remember a similar issue from my colleague. Don't know if this was a special issue with that sytem/software/method or a general thing on Agilent 1100)
It appears you may have answered your own question. Your wrote: " Running the Agilent Tools leak test, it fails with the slope of all plateaus being negative."

Time to do maintenance on the pump head. Replace the piston seals, inspect the piston for scratches, wear and/or any damage (replace if needed). Clean and service the pump. Flush with degassed IPA, than run the pressure leak test AGAIN. *You mentioned that you replaced the seals. Did you use AGILENT factory seals? Did you replace the pistons too? What were the test results? Basic troubleshooting should reveal if there is an issue with the AIV or MCG. Be sure to use fresh liquid and test only ONE channel at a time (100%).

BTW: "Green" status lights on the degasser are of little value. Even the so called "error status" lights on these standalone degasser modules are near worthless. None can tell if there is internal damage or flow path contamination (which there will always be after a period of time as the parts wear down).

    IF it is more than 5 years old and a standard G1322A, then it is probably damaged internally, contaminated and due for professional service.

    If it is a G1322A with after-market Systec kit (0.5 mL chambers inside) installed and is 4 or 5 years old, then it is probably damaged internally, contaminated and due for professional service. Compared to the original G1322A degasser, the typical Systec kit has poor chemical compatibility so can easily be damaged from use with THF, chloroform, Hexanes etc. The Systec kit also by-passes the factory error system so you can no longer use the Agilent/HP status indicators to determine if the system is broken. It may appear OK when it is in fact damaged.

    If it is a G1379A or B, and is more than 3 years old, then it is most likely damaged internally and due for service (these modules last a short time).

Professional HPLC Vacuum Degasser Service: http://www.chiralizer.com/hplc-degasser-repair.html
Some useful info to know.... and more comments.

What flow rate are you running?
What solvent are you using?
What is the normal back-pressure on the system when it is running?

ALL testing should be done with a restriction capillary in place of the column to provide enough back-pressure to stabilize the system (Usually 50 bar or greater). Failure to maintain sufficient pressure in the system will result in poor pump performance.

Did you install fresh clean solvent pickup filters?
Did you clean the bottles? Is the tubing clean and are all the connections proper with no leaks, damaged threads etc?

BTW: Do not by-pass the bead mixer. Do not by-pass the pulse dampener (which also acts as mixer to).
"Diagnosing & Troubleshooting HPLC Pressure Fluctuation Problems (Unstable Baseline) "; https://hplctips.blogspot.com/2014/01/diagnosing-troubleshooting-hplc.html
Consumer Products Guy wrote:
It looks like you've done many of the logical steps.

If it was my system, I would de-gas the IPA the old fashioned way (vacuum-filter through 0.45 micron membrane) and temporarily route the IPA directly into the pump, and see how the test goes.
Thanks for the suggestion. And that's exactly where I ended up. It was still performing poorly (ripple consistently > 1%)
Hollow wrote:
could it be a misconfigured solvent compression setting?
Did you calibrate your solvent with that special "calibration tubing"?

(I don't have much experience with Agilent. Just remember a similar issue from my colleague. Don't know if this was a special issue with that sytem/software/method or a general thing on Agilent 1100)


Actually that's a great suggestion, and what I stumbled upon prior to reading your response. So while basically doing what Consumer Products Guy had recommended, pumping IPA through a restriction line at about 2500 psi, I switched the pump's compressibility setting from 'auto', or whatever it was to the value recommended for IPA, and tightening down all fittings and connections a lot more than I would think was necessary, the ripple went from > 1% to < 0.25%. The system then passed the Agilent Leak and Pressure tests.
Multidimensional wrote:
It appears you may have answered your own question. Your wrote: " Running the Agilent Tools leak test, it fails with the slope of all plateaus being negative."

Time to do maintenance on the pump head. Replace the piston seals, inspect the piston for scratches, wear and/or any damage (replace if needed). Clean and service the pump. Flush with degassed IPA, than run the pressure leak test AGAIN. *You mentioned that you replaced the seals. Did you use AGILENT factory seals? Did you replace the pistons too? What were the test results? Basic troubleshooting should reveal if there is an issue with the AIV or MCG. Be sure to use fresh liquid and test only ONE channel at a time (100%).

I did mention in my original post the piston seals had been replaced along with the AIV, solvent line filters, the PTFE filter. All parts are from Agilent. The pistons appear to be in very good shape. Also, I mentioned I swapped the ENTIRE pump head, with all its parts (AIV, outlet check valve, pistons, piston seals, etc.) from another 1100. The results were the same.

BTW: "Green" status lights on the degasser are of little value. Even the so called "error status" lights on these standalone degasser modules are near worthless. None can tell if there is internal damage or flow path contamination (which there will always be after a period of time as the parts wear down).

    IF it is more than 5 years old and a standard G1322A, then it is probably damaged internally, contaminated and due for professional service.

    If it is a G1322A with after-market Systec kit (0.5 mL chambers inside) installed and is 4 or 5 years old, then it is probably damaged internally, contaminated and due for professional service. The typical Systec kit always has very poor chemical compatibility compared to the original degasser so can easily be damaged from use with THF, chloroform, Hexanes etc. The Systec kit also by-passes the factory error system so you can no longer use the Agilent/HP status indicators to determine if the system is broken. It may appear OK when it is in fact damaged.

Thanks. It's not an Agilent degasser. It's a stand-alone, 4-channel Systec degasser. Not a Systec kit for an Agilent degasser. You're right - even though the pump is still working, it's probably due to be replaced.

    If it is a G1379A or B, and is more than 3 years old, then it is most likely damaged internally and due for service (these modules last a short time).
Multidimensional wrote:
"Diagnosing & Troubleshooting HPLC Pressure Fluctuation Problems (Unstable Baseline) "; https://hplctips.blogspot.com/2014/01/diagnosing-troubleshooting-hplc.html



Thanks. Yes, I've seen that. It's worth posting here for reference for others that stumble upon this thread.
"HPLC PUMP SOLVENT COMPRESSIBILITY VALUES"; https://hplctips.blogspot.com/2011/10/h ... ility.html
Jake wrote:
Multidimensional wrote:
"Diagnosing & Troubleshooting HPLC Pressure Fluctuation Problems (Unstable Baseline) "; https://hplctips.blogspot.com/2014/01/diagnosing-troubleshooting-hplc.html

wordle

Thanks. Yes, I've seen that. It's worth posting here for reference for others that stumble upon this thread.

You have created a special value for this website, hope many users will find it useful.
Went through exactly the same thing with two of my sustems. Replaced as Jake did. Ripple went down to below 1% for some time. Now when i turn pumps in the morning the ripple is 6-10%, need to go through a few 5 ml/min cycles and then it goes below 1% only to come back next day. Will try to do the same as Multidimensional described.

P.S. MultiD, Thank you for sharing your wisdom :). If you need a free multidimensional HPLC column I can provide you with one free of charge.
Vlad Orlovsky
HELIX Chromatography
My opinions might be bias, but I have about 1000 examples to support them. Check our website for new science and applications
www.helixchrom.com
We had Agilent 1050 and 1100 systems. When we got our first 1050 unit, we were advised to purge ALL FOUR channels for 5minutes at 5ml/min each at start up each day, even if we were only using 2 channels.

So we kept that as our protocol, both at RD and at our manufacturing facility QC labs, to minimize any chance of issues.....because I knew they'd call ME if things went bad...
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