Scent of a human
Suppose you took clean (or at least thoroughly analysed) O2/N2/CO2/H2O, chilling it down to nearly liqufaction to get rid of impurities and then heating it back to room temperature. This is the input air for a sealed (baked out) bare room with a recently bathed naked man standing in it. The output air is also chilled to condense out the water and then super-chilled to condense out the other chemicals he has exhaled or exuded from his skin, letting only the O2/N2/CO2 escape.
We already know about the relative rates of exalation of water and CO2. What else is in that puddle we'd condense out of the used air? (Trying to understand the shed skin cells is probably too huge a task.)
I don't know how good we are at "figure out what's in here" chemical searches; though we can figure out ways of detecting known chemicals very well. But there's bound to be a lot of different chemicals present. They may vary by time of day; they almost certainly vary from men to women, and there's a hint that they may very with a woman's menstrual cycle.
Something's there. I wonder what it is? Too bad dogs can't talk.
UPDATE Some people look for things like benzene or chloroform in the breath to measure uptake of contaminants, but these are specific searches. I'm thinking of more basic research. A systematic search using many subjects in many states of health might be useful in finding new diagnostic techniques. How much does your body chemistry change when you get such-and-such a disease? Can you "smell" the difference? Once you know what to look for, it might be easy.
Also, chromatography is a very powerful tool, and can separate out chemicals in several different ways.
Labels: Science