Shimadzu LCMS-2020

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

5 posts Page 1 of 1
Greetings,

Our department has a Shimadzu LCMS-2020 and we have been having some problems with mass detection. Using direct injection, I am able to tune the detector. Running through the internal self check everything comes back as working. When we inject a sample though we do not see anything but noise at the detector.

Any feedback would be appreciated.

C
I am sure that there are folks here that could help. They will probably need to know a little bit more such as what is the analyte, column, method parameters, sample prep details, and possibly a few other things.

I have had similar problems over the years with instruments and the solutions ranged from changing the preparation methodology to hitting the instrument with a hammer.

Have you tried hitting it with a hammer?
Just kidding - don't do that.....yet
Alright, I think i have narrowed down the problem to a mostly clogged ESI source. Does anyone have a manual for the Shimadzu LC-MS 2020? I would prefer not to wing it just in case.

C
Shimadzu should be able to send you a pdf of the manual, but look at your hard disk first, if the engineer's got any sense they'll have left the manuals somewhere on the disk when they did the installation.

I assume you mean the "DL" desorbation line is blocked (ion transfer capillary in other manufacturers' language); if so, it's easy to remove and clean, you don't even need to vent the instrument.
If you can't find the instructions: remove the ESI spray thing from above the spray chamber (turn the two metal clips and lift, after undoing tubing etc.). If you have a dual ion source, remove the APCI needle (pull to left). Remove the spray shield (circle with a bit lopped off one side, surrounding the end of the DL; held by two screws, careful with these, they are a bit delicate. Make sure there is some metal mesh in the drain hole so that you don't lose them if you drop them).
Then loosen the two allen-key bolts on the big circular plate at the back of the spray chamber, and pull the whole plate forwards to remove it (it plugs in round the back to some electrical connections which unplug as you withdraw it). Behind you'll see the DL itself is plugged in electrically by a small white plastic connector top left; undo this. The DL is held by two allen-key bolts that fit into slots on two metal plates; loosen the bolts (don't remove) and rotate the DL assembly slightly, and you can pull the whole thing out, forwards. If it's really bad, buy a new one (not cheap). Otherwise, you can force solvent through it, push wires through it, or anything else that seems appropriate to get it clean. Assemble as above, in reverse order! Good luck!
If the DL is really bad, the orifice behind it may also be dirty, or even the ion optics. These are also easy to clean, but the further you go, the better it is to have the manual to guide you.
The only thing that worries me is that if you can see the ion by direct injection, there can't be anything too wrong with the MS (unless you're having to inject a huge amount to get a tiny signal) - so do make sure that it's not a chromatography issue.
post-script: you should have, as part of your installation tool kit, a small Perspex cylinder to support the ESI source when it's been removed, and avoid risk of damaging the end of the ESI capillary.
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