This is why you do not let artificially smelly people stand next to the Q-Exactive

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

BSA Base peak with Engenieer wearing Cologne standing near QE


Next BSA after engineer leaves


normal BSA


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) .

According to

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…


Posted in Proteomics Blog
5 comments on “This is why you do not let artificially smelly people stand next to the Q-Exactive
  1. Very vivid description. Thanks for sharing!

  2. Chloe says:

    Well, the graphs have shown it clearly, but I was wondering whether it is cologne that causes those differences.

  3. John Neveu says:

    ABIRD is the answer to these problems! Come and get them while they are hot!

  4. John Neveu says:

    Polycyclosiloxanes are everywhere! We will all die pickled by their omnipresent accumulation in our fats and brain cells. At least ABIRD can keep our instrument baseline consistent while we slowly choke on our own synthetic chemicals.

    • Mark says:

      In case you never figured it out, decamethylcyclopentasiloxane is a major component of most deodorant/antiperspirants.

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