October 14, 2004

Purdue chemists give an old laboratory ‘bloodhound’ a sharper nose

WEST LAFAYETTE, Ind. – Purdue University chemists have developed a fast, efficient means of analyzing chemical samples found on surfaces, resulting in a device that could impact everything from airport security to astrobiology to forensic science.

mass spectrometer "wand"
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A team, including R. Graham Cooks, has improved the mass spectrometer, a device well known to chemists for its ability to provide information on the composition of unknown substances. Mass spectrometers, essential tools in any modern chemistry lab, are often used by law enforcement to test suspicious-looking residues that could indicate the presence of explosives or drugs inside packages. But while most mass spectrometers are unwieldy, cabinet-sized machines that require samples to undergo hours of intensive preparation before testing, Cooks’ team has found a way to test untreated samples right where they are found with a mass spectrometer that can fit in a backpack – all by creating a wand that can gather the samples from the environment quickly.

"We’ve essentially given an old bloodhound a new nose," said Cooks, who is the Henry Bohn Hass Distinguished Professor of Analytical Chemistry in Purdue’s School of Science. "While mass spectrometry is one of our best ways to determine the makeup of a substance, the time and effort needed to prepare samples for analysis have made it difficult to use them in the field. With luck, this research will change all that."

The research, which appears in today’s (Friday, Oct. 15) issue of the journal Science, was conducted by first author Zoltán Takáts with Justin M. Wiseman, Bogdan Gologan and Cooks, all of Purdue.

Gologan said that the team’s innovation was inspired in part by the desire to use one of chemistry’s most powerful tools in less limiting environments than the laboratory.

"Testing an unknown sample using standard mass spec can take up to half a day," said Gologan, a graduate student in Cooks’ laboratory. "You have to dissolve the sample, then dilute the solution, then add additional compounds before you can stick it in the spectrometer. It’s a generally effective process, but it’s not so attractive in situations where time is of the essence."

To simplify these preliminary steps in the process, the team developed a technique known as desorption electrospray ionization (DESI) – a mouthful of a name for a method that is relatively simple to conceive.

"Our device sprays a sample with a stream of high-velocity gas that contains some reac