3 pointsby PaulHoule9 hours ago1 comment
  • fuzzfactor7 hours ago
    Looks like progress is being made in this area.

    Lots of these VOCs detected are industrial chemicals too.

    But I was disappointed there was not even one spectrogram in the paper, with all the data they collected.

    For the human test subjects they used "analysis by gas chromatography and time-of-flight mass spectrometry (GC-qToFMS)."

    That's some sophisticated gear.

    For the mice, it's a different rig:

    >breath from all mice was characterized using two-dimensional gas chromatography (GCxGC)-MS

    Actually these GCxGC instruments can accomplish more challenging separations in some ways but are less traditional and even more complex, with fewer qualified operators.

    The code & data appears to be available, with spectrograms at https://massive.ucsd.edu/ProteoSAFe/static/massive.jsp but you have to have an account with the university to look at the files, plus in their standard raw format you need similar instrument software in your lab or workstation to open the files properly, which Windows nor Linux won't even try otherwise. Oh, well I was hoping to take a look.

    Now here's a related paper (no human subjects though) which better depicts other researchers' complex system of sampling, and there is an example GC-spectrogram (Figure 3) from their GC-MS using this next instrumentation:

    >The separated compounds were detected and identified by tof-MS (Bench TOF-dx, Alsmco International, Llantrisant, Wales, UK) using electron ionization at 70 eV with 5 Hz scanning rate and a mass range of m/z 36–350.

    The rest of this raw data, like the example is from, is basically even less accessible without special request, nothing like UCSD which should be turnkey for authorized researchers.