Monday, October 23, 2017

At Your Fingertips

Oct 2017, BBC

"[Your fingerprint] contains molecules from within your body but also molecules that you have just contaminated your fingertips with, so the amount of information there potentially to retrieve is huge."
-Dr Simona Francese of Sheffield Hallam University for the BBC

And this information is now set to be used in courtrooms.

It comes as a surprise to me that this technique is only being used now. We've known since the dawn of the microscope that the labyrinthine ridges of our fingertips are stuffed with bacteria and whatever else in the world we recently touched. We've also been using this mass spectrometer tool since the 1900's, which is also when fingerprinting itself came out.

I’m adding this to the archives here because the mass spectrometer, combined with the gas chromatograph, is the primary tool for detecting odorous molecules. It’s the closest thing to an artificial nose that we have, and it’s the only we to determine with certainty what’s in a smell.

I’ve added below a chart taken from Sigma Aldrich, a supplier of essential oils for the flavor and fragrance industry. It shows the fingerprint, if you will, of the smell of orange.
The smell of orange, as seen in gas chromatograph analysis, courtesy of Sigma Aldrich.

As you can see, the smell of orange has in it way more than just “orange.” In fact, there’s nothing called “orange” in there at all. Limonene and Citronellol might sound like they belong there, but the others are probably foreign to most.

image: Imperial College London site, where you can grow your own fingerprint bacteria on an agar plate 

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