Chromatography Forum

Hello,

I am running on a dionex ultimate 3000 and have been noticing some inverse "shark fin" peaks in my baseline. Initially I thought bad seals or a bad connection. So I ran a "general leak test" to try to see the leak in my system. None was found, but my system still failed the test. The test started around 440 bar and dropped to about 340 bar in the 5 min. So I replaced the seals and am still getting a failing result with approximately the same value.

I do notice a large amount of precipitate on the face of the outlet unit. That is the weird part, because I don't believe any solutions should be near that specific area. The face is only electrical to my knowledge.

All help and ideas are appreciated, and thanks in advance for your assistance.


Tim

Inlet check valve?

Tom - Already replaced.

So the next steps I have gone through were:

Take pump apart and sonicate and clean all parts. Replaced seals. Put pump back together. (I did have a large amount of precipatate on one of my pistons. I wore in the seals, and tried the test again. Starts at about 430 bar, and ends at 310 bar. ---> Fails general leak test again.

So I have ordered new pistons in case there is a scratch I didn't see on them ( I looked carefully)

Do these machines normally fail the general leak test???

Thanks for your help

General leak test)) Looks they have sensor for this trick.
Like in shimadzu detector under flow cell... Try to replace it.

Yes, correct. I check manual http://www.dionex.com/en-us/webdocs/756 ... 01-1-6.pdf

But it is not reason of such peaks... Then you not run pump baseline is ok?

We have Dionex Ultimate 3000 systems and if the leak test fails tightening all the pump fittings will normally fix this, also put the blind nut directly into the purge block, and try a new blind nut as they can beocme worn and difficult to seal.

Can you post a chromatogram of the "shark fin"?
If it is a regular pattern then most like from the pump, if irregular then most likely from detector.
We have had trouble with the mirrors of our VWD-3000RS detectors degrading, could be worth looking at.