Monday, July 27, 2009

Sample, don't trample

The Scientist (Bob Grant)

Historical, archaeological, and paleontological artifacts are precious. And often preciously small: a 500-millimeter fossil fragment, 2 milligrams of charcoal from a prehistoric fire. Decoding the chemical composition of a material—especially things like bone, shell and teeth—can yield a wealth of information about the organism and time to which it belonged. But often studying something means dismantling it, and the thought of grinding some part of these tiny treasures into a fine powder for analysis makes museum curators cringe.

In a lab at the Smithsonian Institution's Museum Conservation Institute in early spring, scientist Odile Madden fingers tortoise shell hair combs and samples of elephant tusks. She explains that one technique can differentiate between an object made out of ivory from an engendered elephant species and one made from cow horn, for example.

Raman spectroscopy can peer into the molecular interstices of many materials, fingerprinting their composition and the nature of their chemical bonds in great detail without harming the object it's probing. Other nondestructive techniques, such as infrared spectroscopy, analyze molecular structure with less resolution. "Infrared spectroscopy can tell you that you have a protein. It can't tell you if you have keratin, which is the protein of horns and hair and turtle shells," Madden says.

See the above page for the full story.

No comments: