How to clean Varian LC-380 ELSD detector?

[bunnahabhain]

Hello everybody

The PQ specs of the Varian LC-380 ELSD are 0.3 mV noise with 1 mL/min water. The best I can achieve is about 0.55 mV. There is no possible combination of gas flow, nebuliser and evaporator temperature that gives better values. I carried out the recommended cleaning procedure (acetone:water overnight, isoprop:water overnight, pure acetone for some hours, poured acetone through the exhaust line etc.) but nothing really helped. I'd like to do some mechanical cleaning, but I don't know how to disassemble the drift tube without damaging the glass. Any experience in doing this around here? Maybe a service manual pdf?

Thanks for any assistance
Jörg

[Chris0000]

Dear Jörg

I you give me a E-Mail Adress, I can forward you the Manual.

Best regards/beste Grüße
Chris

[bunnahabhain]

Dear Chris0000

<edit>
Received the manual. Thanks a lot!
</edit>
Jörg

[bunnahabhain]

After some months I finally took the time to disassemble the ELSD and found that the spring ring that should hold in place the diffusor in the evaporator cartridge is broken (see photo).



I have googled and found that the complete cartridge (Part # PL0890-0475) is about 400 €, this seems to be way too much for such a metal piece. Any idea or hints where I can get this spring? Should not be very expensive.

Edit: I found it on several metal parts supplier's sites: This is a DIN 472 retaining ring (see http://www.norelem.de/de/de/Produkte/Pr ... ungen.html) and costs almost nothing, compared to the complete cartridge...

Regards
Jörg

[bunnahabhain]

OK, replaced the part but my baseline noise is still too high (whatever combination of temperatures and flow I use, noise is always above 0.5 mV.
So I disassembled the optical assembly to see if there are contaminations, but all glass parts were clean. No cloudy parts to be seen, so I'd exlude this as a reason.
Any idea how to get the device back into good working condition?

Thanks a lot
Jörg