HP1090 erratic...everything

[gavinolm]

Hi first time poster here

I have an HP1090
Buffer A = 0.1M TEAA pH 6.0
Buffer B = 75% ACN in H2O
Buffer C = 100% ACN

We noticed a pressure that fluctuates between 7 and 16 BAR. I changed the seals and Heads of the metering pump in question, but yet the problem persists.

I tried to run a known sample and I got a jungle.
Any help from the seasoned vets would be much appreciated.

Also anyone got extra HP1090 they wanna part with ?$?$?$?

Thanks in advance,
Lou

[Consumer Products Guy]

First, put something like methanol or IPA in your three reservoirs, and purge the lines, etc., keep things simple for troubleshooting. You need to determine whether your pressure fluctuation is from the pump, mixing, bubbles, etc. We assume you are degassing your solvents. If pump pressure is steady with your simplified system, then try your different solvents, to isolate whether variable mixing is the issue (1090 uses high-pressure mixing. Keep it simple to isolate the issue.

[rhaefe]

Lou,

If I remember correctly, the 1090 measures the pressure on the low pressure and on the high pressure side (after the booster pump). Where do you see the pressure fluctuations?
Here some suggestions: check the oil level in the booster pump. If it runs low or is too old it can cause problems. By the way, if you change the oil don't forget to clean the reservoir and the little magnet inside. It is designed to trap metal shavings from the booster pump. Also inspect the stainless steel diaphragm in the booster pump. If it showes any signs of wear, replace it. Also the big pulse dampener could be the source of your problems. Inlet and outlet chack valves are also good canditates...

As you see, no direct answer but I hope it helps.

cheers,

Robert

[gavinolm]

Thanks guys for your help, the pressure has levled out but now, I am geting tailing after my peaks. I run a standard and after each peak i get an alligators back of peaks that continue until the end of the run.

I have put a brand new column on and it still persists.

My Boss thinks the mixer may be too old and is crapping out, also I noticed that the 3rd pump is running at half the programmed flow rate (100% ACN), could this be attibuting to the problem.

This HP1090 is just a barrel of headaches. Thanks in advance again
Lou

[tom jupille]

The third channel flow rate problem certainly needs to be fixed, but it may not be the cause of your tailing problems. If you see the same kind of tail on all the peaks, the usual cause is a "funny" flow pattern somewhere in the system between the injector and the column. Look for a transfer line with too-large an internal diameter or, more likely, a bad fitting with excess dead volume. A column headspace or partially-plugged frit can give the same symptom, but you've already eliminated that by changing the column.

[Consumer Products Guy]

Check to see if the solvent reservoir inlet frit on the bad channel is partially clogged, decreasing flow.