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posted by janrinok on Sunday February 23 2020, @03:24AM   Printer-friendly
from the whorl-new-world dept.

Chemists use mass spectrometry tools to determine age of fingerprints:

Fingerprints are telling us more and more about the people that left them behind.

Sure, we all know the unique whorls, loops and arches in a print can identify a person. But now researchers are studying how the natural and environmental compounds within them can also offer clues about a person's lifestyle, gender and ethnicity.

But even as researchers discover new information in fingerprints, they still hadn't found a way to determine a basic fact about a print: How old is it? That's information that could potentially tie a suspect to a crime scene. And that's information chemists at Iowa State University are beginning to provide.

Paige Hinners was using a computer algorithm to objectively analyze the degradation and spread of fingerprint ridges over time—potentially a way to determine the age of a fingerprint—when she noticed something else in her data. The unsaturated fatty oils in a fingerprint were disappearing from her measurements.

"If we're losing them, where are they going?" asked Hinners, who in December completed her doctorate in analytical chemistry at Iowa State and now works as a senior chemist for Ames-based Renewable Energy Group Inc. She worked on the fingerprint project while she was a graduate student in the research group of Young-Jin Lee, a professor of chemistry at Iowa State. Madison Thomas, a former Iowa State undergraduate student, also assisted with the project.

Eventually the research group found answers: As the unsaturated fats—triacylglycerols, to be exact—disappeared from the data, other compounds resulting from reactions with ozone—or ozonolysis—started showing up.

That led to numerous trials and steps to confirm that ozone was causing the degradation of the unsaturated fats in fingerprints. And that led to the conclusion that, with more study, this could turn into a useful tool to determine the age of a fingerprint.

The Iowa State chemists' discovery was recently published online by the research journal Analytical Chemistry and is featured on a supplementary cover of the current print edition.

The paper describes how the chemists used a tool called matrix-assisted laser desorption/ionization mass spectrometry imaging. It's technology that uses a laser to analyze compounds left on a surface then records the mass and electrical charge of each component within a sample, such as the various oils in a fingerprint. The imaging tool allowed the chemists to track the degradation of unsaturated oils due to reaction with ozone in the air.

Residues in fingerprints hold clues to their age

More information: Paige Hinners et al, Determining Fingerprint Age with Mass Spectrometry Imaging via Ozonolysis of Triacylglycerols, Analytical Chemistry (2020). DOI: 10.1021/acs.analchem.9b04765

Journal information: Analytical Chemistry


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  • (Score: 0) by Anonymous Coward on Sunday February 23 2020, @04:49AM (8 children)

    by Anonymous Coward on Sunday February 23 2020, @04:49AM (#961299)

    ~45 years ago I remember visiting a small precision machine shop. The owner offered up a polished bit of steel to show me what kind of surface finish he could achieve...and then hesitated before handing the sample to me.
    "Do you rust?" he asked. I asked for clarification. "Some people leave fingerprints that cause steel to rust very quickly, others not". I reassured him that, when rebuilding small engines, I hadn't noticed any rusty fingerprints after handling degreased parts. Then I got to handle his sample.

    Anyone know if there is truth to this? Or if this machinist was just blowing smoke, trying to impress me (an impressionable kid).

  • (Score: -1, Flamebait) by Ethanol-fueled on Sunday February 23 2020, @04:52AM

    by Ethanol-fueled (2792) on Sunday February 23 2020, @04:52AM (#961300) Homepage

    Fuck Jew shit. Good night, motherfucker, Bernie is good. Now let's laugh at all our misfortune! HAHAHHAHAHHEEHHEEOOOOOOOOOOOOOOOO!

    And, FUCK YOOOOO!

  • (Score: -1, Offtopic) by Anonymous Coward on Sunday February 23 2020, @07:13AM

    by Anonymous Coward on Sunday February 23 2020, @07:13AM (#961331)

    > Then I got to handle his sample.

    You sound like you were a impressionable kid growing up in morally flexible times. Don't stress about it, things happen and no your wife doesn't have to know. Move along, nothing to see here.

  • (Score: 1, Informative) by Anonymous Coward on Sunday February 23 2020, @07:39AM (4 children)

    by Anonymous Coward on Sunday February 23 2020, @07:39AM (#961337)

    Some people's skin oil is more acidic or basic than others. I've heard of this before, and steel-stringed guitar players can confirm. He could have de-greased the object after you handled it but didn't want to be put to that much trouble.

    • (Score: 2) by Runaway1956 on Sunday February 23 2020, @09:36AM (3 children)

      by Runaway1956 (2926) Subscriber Badge on Sunday February 23 2020, @09:36AM (#961358) Journal

      That much effort? https://nanomoldcoating.com/power-clean/ [nanomoldcoating.com]

      There are dozens if not hundreds of similar products on the market. Degreasing is as simple as a child spraying for cooties with this stuff. I take stuff apart, and degrease the parts. When I drill and tap holes, I degrease the holes before putting bolts into them with oil tolerant Loc-tite. I doubt there is a machine shop anywhere that doesn't have a few cans of one of these products sitting around.

      The same site offers five different mold protecting rust preventatives - again, there have to be dozens, if not hundreds, of similar products on the market.

      Degreasing most parts may take all of a minute. Something with caked on grime may take that minute, plus a quick wire brushing, then a few more seconds of spraying. Spraying that part down with a preservative will take almost ten seconds.

      • (Score: 2) by Pslytely Psycho on Sunday February 23 2020, @10:55PM (2 children)

        by Pslytely Psycho (1218) on Sunday February 23 2020, @10:55PM (#961607)

        Since you obviously know this subject well, I must ask.
        He stated this was forty-five years ago. Was it this simple to de-grease a highly polished piece made specifically to show off how good of a surface the shop could produce at that time?

        --
        Alex Jones lawyer inspires new TV series: CSI Moron Division.
        • (Score: 2) by Runaway1956 on Monday February 24 2020, @03:07AM (1 child)

          by Runaway1956 (2926) Subscriber Badge on Monday February 24 2020, @03:07AM (#961696) Journal

          I believe that it probably was. Almost certainly was. There are two people at work who learned the trade directly from George Washington Carver. I can ask them when these mold cleaners were made available to the industry.

          Commercial preparations aside, acetone has been available for all of my life. If I had nothing but acetone available, I'd dunk a sample product like that into some acetone, wipe it with a rag, and never give it another thought after some creature with grubby paws handled it.

          • (Score: 0) by Anonymous Coward on Monday February 24 2020, @04:30AM

            by Anonymous Coward on Monday February 24 2020, @04:30AM (#961717)

            Acetone does a great job but I hate the smell. In many cases isopropyl 91% (drugstore) does a fine job without that bite.

  • (Score: 2) by Runaway1956 on Sunday February 23 2020, @09:43AM

    by Runaway1956 (2926) Subscriber Badge on Sunday February 23 2020, @09:43AM (#961359) Journal

    I leave fingerprints on stuff all the time, like most people do. I don't think that I'm special, in regards to fingerprints, but sometimes I will return to a piece of work to find corrosion starting at a fingerprint. I've never given it much thought, really. Sometimes, my hands are wet. Or, I may have dirty hands. Or, I may have some chemicals on my hand from some product I handled previously. Most of the time when I am at work, my hands probably have oil on them. Hydraulic oil, machine oil, cutting oil, way-lube, some kind of oil.