What makes blood smell metallic?

Swedish researchers asked that exact same question. Odorants, molecules that dissolve in air and find their way into our nasal mucus membranes to interact with our olfactory receptors, must be volatile. So, first, they extracted volatile compounds from mammalian blood. Then they separated and analyzed them for their chemical composition using gas chromatography-mass spectrometry.

(Guess Chem class is good for something!)

Next, to determine which chemical is responsible for “blood smell” they tested each extract with human subjects. Turns out just one compound smells like blood: trans-4, 5-epoxy-(E)-2-decenal. Say that five times fast!

Finally, to make sure this compound could attract large, dangerous predators (to answer questions about animal behavior and olfaction, not to weaponize it…I hope), they compared the responses of wild dogs and tigers to blood, blood odorant, a fruity odorant, and a control solvent by soaking wooden blocks in the substances. Turns out dogs and tigers love blood odorant as much as the real thing.

Tigers don’t know it’s not blood!

1 thought on “What makes blood smell metallic?”

  1. Here’s how I found this out. First I went to Web of Science through the Clemson Libraries page. Then, I searched for blood odorant. This turned up 751 articles. So I refined my search using the keyword “metallic”. This narrowed the field to just 4 articles.

    I can quickly scan just 4 articles!

    The first article was a chemistry paper about how to synthesize the odorant, but didn’t explain how it was discovered. The second article was the one linked above and explained the isolation (via a reference to a masters thesis, I believe), and the interesting tests to confirm the metallic odor.

    If you perform a Google search I think you can also find a blog that cites (and links to) this study.

    Note: the other 2 articles seemed irrelevant, so I didn’t read them.

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