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Lipstick smears are not a particularly common piece of trace evidence – they’re more often found in hardboiled detective novels. Nevertheless, the colorful chemical mixtures do appear amid the chaos of a real-life crime scene from time to time.
But analysis of the cosmetic compounds is complex, and has traditionally taken time-consuming processes to identify accurately.
Now a group of scientists at Western Illinois University contend they have perfected a simpler method to analyze the particular lipstick for forensic analysis, that they’re presenting at a major conference today.
The method involves adding an organic solvent to remove the oils and waxes in the cosmetic. A second solvent then isolates the remaining residue.
That residue is a particular recipe for the lipstick brand and make – and the analysis of the molecules by gas chromatography then identifies the unique signature.
“Working on this investigation has opened my eyes to the fact that TV has it wrong – things take much longer in real life,” said Bethany Esterlen, an undergraduate researcher who led the project.
The team has a library of 40 lipsticks they can identify – though they’ve only worked with smears on paper so far, they said.
“Right now we are just lifting samples off of paper, but in the future we are hoping to use different articles and media that could be found at a crime scene,” said Brian Bellott, the assistant professor of chemistry whose laboratory hosted the work
The techniques would require no new tools or technologies for current forensic labs, Bellott added.
The team is presenting their results at the annual meeting of the American Chemical Society in San Diego this afternoon.
Other methods of lipstick have been used in forensic analysis in recent years. Paper chromatography is used in some labs. A more-advanced analysis using Raman spectroscopy was announced by British researchers at the University of Kent in 2013 – but is more time-consuming and expensive than the new gas chromatography technique, according to the Western Illinois University team.