Blue Growth

[skirchmann]

Recently on our Waters HPLC instrumentation, we have been seeing a blue growth at the base of the pumps near the check valve housing. We do not seem to have this problem with our other HPLC. The growth is blue, crystalized in structure, and leaves blue stains on the metal when it is cleaned off. Cleaning with IPA and water generally remove most of the growth for a couple of months, but we are not sure what this is. Anyone have any ideas?

Thanks for the help,
Stephanie

[scottythree]

Anyone using Copper sulfate in their mobile phase?

[skirchmann]

Not that I am aware of. Although there are various different mobile phases used, I don't belive we have any methods using copper sulfate.

[nonagon]

This sounds like salt precipitation, corosion of metal parts (pump, degasser) or both.
are you using high salt or boric acid in mobile phase?
are you running buffered aqueous solutions and organic solvents from same channel without washing?

[skirchmann]

We are running buffers and organics in our mobile phases. I am hoping that the instruments are being rinses thoroughly before they are being used, but with so many analyst using the instruments, it's impossible to tell. Also, why would the salting turn blue? We have had our instruments salt out before, but can't figure out why the precipitant is turning blue.

[nonagon]

Are you using an alliance 2690/2695? (I'm writing as if you do)
try this
check the check valve if it is properly tightend and see if the cartridge is positioned correctly (arrow pointing to pump housing) you may want to replace the cartridge to be on the safe side, give everything a proper cleaning, follow manual at all times.
as for the blue colour - check for corrosion. the best place to start is the degasser, you can (or better yet have a certified technician) remove the side cover and visualy inspect the degasser, in case of corrosion the degasser gets it faster and harder. Then check the pump; parts in the piston housing (seal, washers, plunger etc.) may loose their integrity due to corrosion or drying and bleed out as blueish precipitate with salts from mobile phase.
I hope this is a simple check valve issue with some extraneous blue thingy. other problems are quite expensive.