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News In Brief: Lipstick smudges reveal their identity

Spectroscopy allows forensics researchers to tell cosmetics apart

By
11:36am, February 26, 2013

WASHINGTON — Discerning one lipstick from the next can be tough for consumers but it’s even harder for scientists. Now forensics researchers have found a quick method to tell apart individual lipsticks, no matter the color or brand. The approach could help investigators analyze evidence in cases in which a smear of lipstick on glass, paper or a piece of clothing becomes important.

Experts typically examine a lipstick’s dyes or its chemical or elemental composition. To distinguish closely related cosmetics, those approaches usually need to be combined, said Paige Gardner of Virginia Commonwealth University in Richmond. She decided to tackle 80 lipsticks with Raman spectroscopy, which zaps a sample with laser light, making some of the molecules vibrate. These tickled molecules emit light of a frequency different from what came in, and researchers can read that shift in frequency like a chemical bar code.

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