Dear Sir,

Good day! It's looks like you have Polypropylene glycol in your system (or, I think, in your solvents)... Have you tried to stop mobile phase and look at the background? Are this ions still high or they are going down? If they are still high - look at your tubes from N2 generator. I had problems with polyamide tubes (m/z 214, n-BBS), but when I changed them to the teflon - all problems have gone.

P.S. But I think that this is problem with solvents...

P.P.S. Sorry for me English :-)

Best wishes,

Azamat

Thanks Azamat!  Good suggestions.  We have tried no flow to the MS, and there is still background.  We replaced the oil and hydrocarbon trap on the N2 generator, and still no change (we did have problems with the N2 generator before though, even though all the tubing is teflon).

I'll look more at the possibilities for polypropylene contamination - we've been running a lot of heptane on the system, so yes, it's possible that this is causing some sort of plastic to leach out of the system.

Dear Alastair,

Do not ask me the question I cannot answer.

We do not have  any MS at all.

Best regards

AK

Hi Alastair

Did you figure out what the m/z 417 was? And how did you manage to get rid of it? I am having the same issue. 

Thank you,

Ali