It is known that some volatile organic compounds smell good at low concentrations but smell unpleasant at high concentrations. For example, certain perfume components. Can anyone give some specific compound names?
Hello Kan - there are a few compounds that are associated with just an opposite effect to which you described, i.e., they have offensive odor at low concentrations that tends to be less offensive with higher concentrations. These compounds are common to livestock waste. These are p-cresol (4-methyl-phenol), and to some extent, indole. P-cresol at low, diluted concentrations (e.g., downwind) is a 'signature' for livestock waste. At very high concentrations, the compound has more 'medicinal', 'cleaning agent'-type notes. Curiously enough, indole is also used in perfume formulations which initiated your question.
The observed effect for p-cresol is described for example here:
Koziel, J.A., L. Cai, D. Wright, S. Hoff. 2006. Solid phase microextraction as a novel air sampling technology for improved, GC-Olfactometry-based, assessment of livestock odors. Journal of Chromatographic Science, 44(7), 451-457.
I hope it helps a little bit. With kind regards,
Jacek
http://chromsci.oxfordjournals.org/content/44/7/451.abstract
Hi Dr Koziel,
Thanks so much for sharing with me your thoughts. Along with your line of your thought, I checked out indole and understood a little bit about it. Looks like it has something to do with the number of olfactory receptors that respond to the odor.
http://www.leffingwell.com/olfact5.htm
Kan
Hi Kan,
I’m agree and fully support Jacek. From the physiologist’ point of view, the ratio of components in the mixture rather than concentration play the important role in animal olfaction and social recognition by smell. Currently we know about 35 chemical compounds in Mammals with pheromone activity and by analogy with the alphabet – the ratios of these compounds (letters) in the mixture form countless combinations (words) which form the whole sentences also. This chemical language organizes «individual fingerprints» (=perfume bouquets) or olfactory signatures in Animal Kingdom. Also the great importance plays the recipient genotype and his experience.
Best regards,
Sergey
Hi Dr Nivikov,
Thanks for your answers which offered deep perspective and new insights. May I ask how many different olfactory receptors are in the human nose? And how many are there in, for example, dogs? I believe with your expertise, you will shed more light on this topic.
Best,
Kan
About 220 millions in dog, about 5 millions in humans. About 1200 different receptors in Mammalia...
That's OK?!
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