underivatized amino acids in the gas phase

[Peter Apps]

I found a reference to analysis of underivatized amino acids from the headspace of blood using a z-nose, which has a very short GC column programmed very rapidly; http://www.estcal.com/TechPapers/Odor_of_Blood.doc

Two things surprised me; amino acids being in the headspace of an aqueous sample in the first place, and underivatized amino acids surviving GC analysis (albeit under extreme conditions).

I am trying to determine what compounds African wild dogs use to send chemical messages, and if amino acids have to be added to the list of potential messengers the task will be more difficult.

Does anyone know of work that confirms the presence of vapour phase amino acids, with reliable identifications by GC-MS rather than just retention time ?

Thanks
Peter

[Ron]

There are several light amines that have significant vapor pressures and can exist in the headspace above a sample. For example, putracene and cadavarene are two amino acids given off by rotting flesh that are part of the aroma from decaying bodies.

[bhuvfe]

Peter,

It's indeed bizarre that aminoacids are visible in those conditions. But from what I understood the Z-nose uses a kind of dynamic headspace. You trap your volatiles on tenax and then thermally desorb them on a very short column. Besides that the sensitivity of the detector is claimed to be in the pg range.

I have a DHS system from Gerstel (I've just started to use it..) and I've seen that SVOC till mw 530 (irganox 1076 a polymer additive) are visible in scan mode.

If I find some standards of aminoacids hanging around in the lab I might give it a try (no promises..).

Regards,
bhuvfe

[Peter Apps]

Hi bhuvfe

If you do get a chance to check this out it would be very interesting.

Ron, cadaverine and putrescine are not amino acids, they chromatograph nicely on an inert system, being neither very polar nor thermally labile under GC conditions, and they have enough vapour pressure to get unmistakably ! into the vapour phase.

The z-nose "identifies" things by comparing retention times with those of standards, it is possible that both the experimental and the standard amino acids were decomposing on column in the same way. This still leaves amino acids in the gas phase of the sample, but confirms that they are not amenable to GC unless derivatized.

I recall seeing a paper in which ambient electrospray MS found a range of "non-volatile" compounds floating around in the air. For sure some of these are adsorbed to particles but quite a few "non-volatile" compounds seem to have enough vapour pressure for them to be detecable by GC (if they survive the heat) and certainly by odour - if their structure gives them a smell.

Peter