Real-life "tricorder" for chemical analysis.

Purdue University researchers have created a handheld sensing system that its creators liken to the Star Trek "tricorder" that characters in the television series use to analyze the chemical components of alien worlds. The real-life system has down-to-earth applications such as testing of foods for bacterial contaminants like Salmonella.

This ultrafast chemical-analysis tool promises to have numerous uses in detecting everything from cancer in the liver to explosives residues on luggage and "biomarkers" in urine that provide early warning of diseases.

The instrument consists of a miniature mass spectrometer combined with a technique called desorption electrospray ionization, or DESI. The device and the technique were developed by a team of researchers led by R. Graham Cooks, the Henry Bohn Hass Distinguished Professor of Analytical Chemistry in Purdue's College of Science.

"Conventional mass spectrometers analyze samples that are specially prepared and placed in a vacuum chamber," Cooks said. "The key DESI innovation is performing the ionization step in the air or directly on surfaces outside of the mass spectrometer's vacuum chamber."

Unlike conventional mass spectrometers, which are cumbersome laboratory instruments that weigh more than 300 pounds, the new handheld device weighs less than 20 pounds and can be used in the field.

"We like to compare it to the tricorder because it is truly a handheld instrument that yields information about the precise chemical composition of samples in a matter of minutes without harming the samples," Cooks said.

The researchers at Purdue look for compounds that indicate the possible presence of a particular substance, such as cocaine or explosives residues. If these indicators are found, the equipment performs a more in-depth analysis to determine the exact chemical structure.

The research team has used the device to analyze clothes, foods, and tablets, and to identify cocaine on $50 bills in less than 1 second.

Two startup companies have been established on the basis of DESI and the portable mass spectrometer: Prosolia, Inc., of Indianapolis, has commercialized the DESI source, and Griffin Analytical Technologies LLC, of West Lafayette, Indiana, has commercialized miniature ion trap mass spectrometers.

For more information, contact R. Graham Cooks at [e-mail].