The Q-exactives seem to be much more sensitive to environmental contaminants than our pervious instruments (LTQ’s and LTQ-FT’s). Here is an example of two BSA QC’s run back to back .The only difference is that for one of them a HPLC service engineer with a lot of cologne was standing next to the Q-exactive. Notice the 371 background ion goes from 10^5 to 10^8 and totally swamps out the base peak ion chromatograms!
BSA with cologne wearing engineer nearby
Next BSA after engineer leaves
I’m going to have to put up a sign or something, Only naturally occurring body odor allowed in the instrument room!
Just a small update (oct 13 2014). So you maybe wondering what that 371 ion is (it’s actually seen all the time with nano-spray) .
Interferences and contaminants encountered in modern mass spectrometry which BTW is the definitive guide to such things.
371.10 is a Polysiloxane, specifically (decamethylcyclopentasiloxane) . Keller actually states that the 371 ion should be followed by a 388 (which we do not see) but it’s a good bet that’s what the 371 is. What is Polysiloxane doing in perfume. No idea…A Google search on the topic does pull up some clues. Such as this and this. Apparently it not only “leaves a silky smooth feel on your skin” it really wreaks havoc on my instruments….sigh…