Well, I did a lot of looking, and couldn't find much info about specific chemistry of perfume decomposition. Only two things. (Just to explain why I didn't find more of this stuff - I can't use my usual sources, since this ain't work-related).
I found one case where a natural frag chemical (guaiazulene, in blue chamomile) in a sunscreen was exposed to artificial sunlight for 3 hours (including both UVA and UVB), and the content of guaiazulene in the sunscreen was reduced to only 21% of the original amount! Meaning almost 80% was destroyed in just 3 hours of direct sun, even in the presence of UV-absorbing substances, and boo-koo of them. Ouch!
The other thing I found is actually very helpful, but it's not about frags, per se. It's about the fragrance of beer (sorry about that, Dullah, but beer does appear to be useful for something - in this case helping us to understand frags!
). I turns out that the chemistry of "skunky" beer has been a mystery for many years, but the final answer wasn't found until fairly recently. I won't get too deep in the chemistry, because it's pretty complicated. But the lowdown is that:
1) Skunky beer comes from small amounts of sulfur-containing compounds which are formed due to light exposure.
2) It happens due to visible
3) It happens with clear or even green glass, but is diminished by amber glass.
4) The basic mechanism is that a substance other than
the fragrance chemicals themselves absorbs the light, and that substance
is the bad actor that starts everything. The fragrance chemicals are never themselves electronically excited by the light, which in their case would have to be UV. In the case of beer, the bad actor is riboflavin.
5) The substance that does absorb the (visible) light then steals an electron from the fragrance chemicals, and that starts a path which not only eats up the fragrance chemical, but also creates a new, stinky one.
6) The implications for frags are: (a) glass can mostly stop UV, but your frags are still at risk for sunlight damage by visible light, unless they are in dark or opaque glass (as Astaroth said). (b) although UV normally does more damage per photon, it is the specific frequency activating whatever bad stuff is actually possible that is the most dangerous, and (c) whatever happens depends markedly on the total mix of substances which are present in the juice, and what bad things are possible given that mix.
But in any case, I would agree that we have to be careful not to get too retentive about our frags. Cool and dark is good, the more, the better, but not so much that it gets in the way of enjoying your frags. Which is why Luca Turin apparently just sticks his on a shelf where he can see them!
Now, still, I do like Irish's suggestion about actually demonstrating what can happen (even if he was only trying to scam us out of our good stuff!
), so I'd like to do some kind of home experimentation, sorta like a Great Internet Perfume Skank-Off
. We can get pictures and scent reports on pairs (or greater) of vials, one a control, and the other(s) subjected to various skank-inducing conditions. Not exactly hardcore science, but we can't exactly afford to buy a GC-MS on Grant's spare server change. Still we can do some simple bathroom science that's kinda fun, and will definitely give us a feeling for the magnitude of this thing.
So what I'm saying is that we should stop simply whining about those frags we don't like, and actually get a bit medieval on 'em! Whaddaya say, people? <evil scientist laughter>Bwah-ha-ha-ha-ha!
</evil scientist laughter>. Who's with me? <signature revoked below/>