September 13, 2008

Fingerprints Go High-Tech

By Castelvecchi, Davide

New tests can reveal signs of explosives, drugs Fingerprints can tell a lot more about people - what they've touched, what they've eaten, what drugs they've taken - than just their identities. A new analytic tool could make it easier to spot terrorists and diagnose diseases from telltale chemical markers.

The method, described in the Aug. 8 Science, can map a fingerprint based on the presence of virtually any water-soluble chemical. "It's the difference between a black-and-white picture and a full-color picture," says chemist Graham Cooks of Purdue University in West Lafayette, Ind.

Cooks' team singled out traces of chemicals such as the explosive RDX and cocaine.

The researchers used a technique called DESI, pioneered by Cooks and collaborators in 2004. In DESI, researchers spray microscopic droplets of water onto a sample. The first droplets that hit the sample form a film that dissolves chemicals on the surface. When additional droplets splash onto the liquid film, some droplets bounce back and are sucked into a tube.

There the droplets are dried to isolate any chemicals in the sample. Mass spectrometry then identifies molecules according to their molecular weights.

Traditional mass spectrometry requires samples to be analyzed in a vacuum, while DESI can be used in the field.

"DESI is extremely powerful and promising," says chemist Facundo Fernandez of Georgia Tech in Atlanta.

DESI might also be useful for medical diagnosis. Fingerprints may contain chemicals that are not found with blood or urine tests and that indicate a disease's presence.

Copyright Science Service, Incorporated Aug 30, 2008

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