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Fingerprints have substance. They are physical residues of the grease from the fingers. Current fingerprint analysis looks at the pattern in which this grease is deposited, but sometimes this is smeared, small or otherwise inadequate.
I propose that considerable information could be gained from
the grease itself. The components of this grease varies from adults to children (link) and I suspect it would also show considerable variation between individuals. Gas chromatography / mass spectroscopy could be used to define and quantify components of a fingerprint, which in turn might provide information about the sex and race of the individual - or possibly even more information might be learned.
Mass spec on fingerprints.
http://www.ornl.gov.../mr19950327-00.html
[bungston, Oct 04 2004, last modified Oct 06 2004]
Related idea.
http://www.halfbake..._20genome_20project
[bungston, Oct 04 2004, last modified Oct 05 2004]
DNA from fingerprints
http://www.futurepu...rchives/001568.html
[DrCurry, Oct 04 2004, last modified Oct 06 2004]
Skin lipid profiling.
http://www.jlr.org/...ntent/full/43/5/794
[bungston, Oct 04 2004, last modified Oct 06 2004]
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//information about the sex and race of the individual//... I'm not sure you can glean that much information from fingerprints. There isn't any DNA in them, and the composition could vary tremendously depending upon external contaminants, ie. food. |
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<pitchforks and torches>I say we round up all those Specs and get their oily prints!</pitchforks and torches> |
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Why on Earth try to figure out what mass spectroscopy can tell you about identity when you can already extract DNA...? (See link.) |
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The majority of what you'll get in fingerprints is lipid (ie fats) from the fingers, mostly triacylglycerols but some cholesterol as well (finger lipids are a common contaminant in our trace lipid analysis lab). There is insufficent variation between individuals to make this suitable for the kind of forensic stuff you have in mind. You can't always even determine animal species from the lipids, unless you use complementary techniques such as compound specific isotope ratio mass spectrometry. |
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You will also get a small amount of genetic material, but this isn't suitable for GC/MS analysis as it stands because it's the molecules are too large. You'd have to hydrolyse the DNA and then you'd lose the personal information it carries. As [Dr C] points out, there are good ways to do this using other techniques. |
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Skeptics - you understand that this idea has nothing to do with DNA, which I agree could not be meaninfully analyzed with GCMS. The lipids and other volatiles on human skin are extremely complex. I fooled around a little with this back in the day and was amazed at the number of peaks that could be obtained by an ether rinse of skin. I have always wondered about whether such patterns were consistent from day to day - an interesting study would be to collect samples from a classroom on several different days, then collect a final sample and see how many could be identified based on this data. |
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Hazel - you assert there is insufficient variation between individuals as regards these volatiles. Linked is the only study I could find on this (sorry for those w/o full text access). These folks found great complexity. If you know different I would love to learn. Or even better, if you have a lipid analysis lab would be to do the experiment! |
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I believe that we secrete RNAses from our skin to defend against RNA viruses. Perhaps these RNAses would vary from person to person and could be sequenced. |
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The study does say they find great complexity but they also say |
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//analyses of ethanol extracts from six different individuals showed a relatively homogeneous composition with the presence of the same compounds (hydroxylated FAMEs, Sphes, Sphas, Phyts, and 6oh-Sphes) in relatively close molar compositions// |
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which suggests they think there isn't sufficient variation to identify individuals. However, they also point out that |
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//the composition could be extremely different between different skin extracts [from the same person], especially due the conditions of skin washing before performing the ethanol extract// |
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suggesting that it may be possible to determine from finger lipids whether someone had washed their hands etc before leaving it. So there may be some forensic use in that way. |
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[UB] - or one that just had a lot of time on their hands. |
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ahh those bored, idle forensic scientists. Where would we be without them? |
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