Agilent 1100 HPLC air bubble and baseline problem

[MitchHowell]

Hi everyone,

I encountered strange problem on Agilent 1100 Quart pump

My method uses 90% water and 10% methanol with C18 column. Recently I saw some bubbles coming out from MCGV valve and the pressure fluctuated between 80 bar to 120 bar (up and down, down and up) gradually. Sometimes the air bubble is moving in and out from active inlet valve (AIV).

I have replaced the MCGV, AIV and bubbles were reduced, but the bubble is still coming out after I pumped for 10 minutes. I have also changed the whole pump head (piston, seal, outlet ball valve, purge valve, frit), pump head driver motor and damper unit. I have also bypassed the degasser.

If I use single channel, say B at 100% (methanol 100%), the pressure is stable at 80 bar. The same stability goes with A at 100% (about 110 bar, constant). Once i use 90% water and 10% methanol, the ripple reading will start to go up from 1% to 12%! Both mobile phases have been replaced with new ones from brand new source in case of contamination. A new column is used too.

There are no change in method settings include compressibility, minimum strokes etc.

Does anyone have such experience before? Thanks for sharing.

Mitch Howell

[Consumer Products Guy]

I have also bypassed the degasser.

That's not a good thing !!!

Question: are you purging ALL FOUR channels at 5.0ml/min. for 5 minutes EACH, sequentially, even though you are only using two channels? This is IMPORTANT.

[agilentchina]

Your problem about Agilent 1100 is because of your degasser chamber contaminated. You can purge all the channel with 30% nitric acid for more than 30 minutes, then purge with water for 30 minutes. you must not connect the column and detector when you clean the channel. If the method doesn't work, you had to change the degasser.

I need some used Agilent 1100 HPLC, 1200HPLC, 6890GC, and 5973 or 5975MSD,if you know some information about these, please connect with me. thanks. My email is wululing@yahoo.com

[DSP007]

Hi, sorry for the "Pigeon Inglish, native Russian
Yes , it is degasator problems. But its not contamination problem, its membrane destruction problem. For localisation problem - off line degasator , and use vaccuum degasation phase from Buchner / TFE filter. Realy , need the technical servise

[MitchHowell]

Hi everyone,
Thanks for reply.

I also realised it is more like degasser problem. I opened the degasser and found liquid inside the degasser chamber and vacuum pump. I have replaced the degasser chambers, vacuum pump, solenoid. The ripple dropped to 1-2% gradually and pressure is stable.

Unfortunately the problem did not go away. After 1-2 hours, the ripple climbed up again to 15%. I am almost fainted because I do not know what to change now.

Thanks.

Mitch

[MitchHowell]

Hi Agient China,

I also want the used Agilent system. Why does Agilent China want the used systems? Sell to customers or to support obsolete products? Thanks.

Mitch

[MitchHowell]

Hi Consumer Products Guy,

Thanks for your recommendation on flushing all channels. I flushed a and b only and leave c and d capped.

Unfortunately I do not have another degasser to work with. Is there anyway to degass the mobile phase. Helium sparging is out because I do not have helium. Can ultrasonicating the solvent work?

Thanks.

Mitch

[Jiri Urban]

Can ultrasonicating the solvent work?

10 - 15 minutes of ultrasonication every morning should be ok.

[Consumer Products Guy]

Hi Consumer Products Guy,

Thanks for your recommendation on flushing all channels. I flushed a and b only and leave c and d capped.

Flush them all !!!!
Did I say to flush them all ???

Is there anyway to degass the mobile phase. Helium sparging is out because I do not have helium. Can ultrasonicating the solvent work?

Ultrasonic can help to degas. So can stirring while pulling good vaccuum. So can vacuum filtration through a membrane. But you'll still need to flush all four channels. Did I make that clear ??

[AMIR HAIDER]

Mitch Howell,
You have given complete detail of your performed exercise it is very helpful for conclusion.
You said ''I have replaced the MCGV, AIV and bubbles were reduced, but the bubble is still coming out after I pumped for 10 minutes. I have also changed the whole pump head (piston, seal, outlet ball valve, purge valve, frit), pump head driver motor and damper unit. I have also bypassed the degasser."
but you haven't mentioned the use of filter/spargers in the mobile phase. If you are using filter/spargers do some more take glass beaker in which your spargers/filters completely dipped in both respective solvents like methanol and water and sonicate them on ultrasonic bath for 10 min, and bring that both small beakers near your HPLC system after sonication don't expose your spargers/filters expose to air before fixing tubing, fix the instrument solvent delivery tubing of your mobile phase in respective filter/spargers and starts flow you mobile phase, some time air trapped in these filter/spargers.

You are using Agilent 1100 Quart pump and I again appreciate you because you have already done what an outside hired HPLC technician should check as you said
"If I use single channel, say B at 100% (methanol 100%), the pressure is stable at 80 bar. The same stability goes with A at 100% (about 110 bar, constant). Once i use 90% water and 10% methanol, the ripple reading will start to go up from 1% to 12%! Both mobile phases have been replaced with new ones from brand new source in case of contamination. A new column is used too."
If the above mentioned case is, then it’s clear from your statement that the problem is raised from the gradient pump which is taking air bubbles during taking mobile phase from different reservoirs,so make a single mobile phase for working until some outside hired HPLC technician replace the mixer in your pump.
Regards
AMIR HAIDER

[DSP007]

Hi
Water after distillation or reverse osmosis system contains a small amount of dissolved air
If degassing is dead, air bubbles are distinguished by mixing water with an organic solvent for the pump, which leads to a pressure jump and in the detector - which leads to false peaks

[carls]

Check the tightness and condition of all tubing and fittings on the degasser, the MCGV and the AIV. Air leaks after the degasser can cause this. In case you're wondering, yes, it is possible that a fitting will leak air (in) while not allowing liquid to leak (out).

[MitchHowell]

Thanks Carl, DSP007, AMIR HAIDER AND Consumer Products Guy,

I used another loan degasser. For about 3 hours, the pressure was stable with ripple below 5%. I will monitor the pressure for next 12 hours.

I wonder what could be wrong with the my old / faulty degasser. I have replaced the vacuum pump but amber LED always appears. Could be the chambers or solenoid.

Thanks for help,

Mitch

[MitchHowell]

Thanks Jiri Urban too.

[Consumer Products Guy]

I used another loan degasser. For about 3 hours, the pressure was stable with ripple below 5%. I will monitor the pressure for next 12 hours.

Our ripple is routinely under 0.5% (ten times less than what you have). I believe the max spec is 2.0%.

I'm refering to 1050 vacuum degasser here, haven't taken apart an 1100: Check the rubber vacuum tubing for cracks or loose-fitting ends; if found, get some vacuum tubing from auto parts store or from Agilent.