University Of Arkansas Researcher Studies Pollution, Polymers

FAYETTEVILLE, Ark. - A University of Arkansas researcher has received over $1.3 million to study particles and polymers, the first to determine the role of particulate matter in harmful pollution, the second to better understand the properties of polymers - commonly found in cars, clothes and other household goods. His work may also one day have applications in fighting bacterial infections.

Charles Wilkins, Distinguished Professor of chemistry and biochemistry and director of the Center for Sensing Technology and Research (CSTAR), has received funding from the National Science Foundation and matching university funds to create an instrument that will allow the mass spectrometric analysis of small particles.

In recent years, the Environmental Protection Agency has regulated small particulate matter because researchers believe that such matter may be dangerous to human health. Small particles stay in the lungs longer than large particles, sometimes for months, creating more time for contact of hazardous materials with human tissue.

Currently, however, science has no method for accurately characterizing all chemicals in single particles.

"If you could analyze a single particle for both size and chemical composition, you could generate a list of particles of different sizes and the types of chemicals found on each particle," Wilkins said. "Then you could make a more informed evaluation of which particles are the most dangerous."

Wilkins plans to modify a Fourier-Transform Mass Spectrometer to analyze particles one at a time and determine the particle’s source and the chemicals it contains on its surface. To do so, he will use multiple lasers as "electric eyes" to measure the speed of the particle as it is shot into the chamber.

Using the speed, the researchers will know when to fire a laser to ionize the chemicals contained on the particle’s surface. They can then use the mass spectrometer to analyze those materials and identify them.

The researchers can also turn up the power of the laser and blow the particle into little bits to analyze the particle itself. Particles come from many different sources, including soil, sea salt and diesel fuel exhaust.

"Knowing the composition of the particles may be useful in determining their origin," Wilkins said. "If you don’t know their origin, you can’t do anything to control them."

This technology may also be applicable to bacteria, which correspond to the particle size range Wilkins plans to study. The mass spectra could serve as signatures for particular types of bacteria, which could then be compared with a library of such signatures. This could solve a current problem facing medical laboratories, where it often takes days to grow enough bacteria to determine their specific identity.

"Most of the time, treatments for infection must be an educated guess based on the symptoms," Wilkins said.

Wilkins has also received NSF money to use the mass spectrometer to analyze synthetic polymers, commonly found in household plastics, synthetic materials and automobiles. Polymers typically consist of chains of chemical units linked together in certain patterns. Changes in those patterns change polymer properties - from solid to liquid, for instance. So when companies produce a new polymer, they want to know its detailed structure so they can relate it to the molecule’s function.

Polymers typically remain stable under most conditions, but using a laser, they can be fragmented and turned into ions, which scientists can analyze using mass spectrometry. Then the researchers take the fragments and put them together to determine the structure.

"It’s a little like working crossword puzzles," Wilkins said.

The grants have allowed Wilkins to purchase materials to develop the new aerosol mass spectrometer and update an existing mass spectrometer so that these techniques can be incorporated into the machine’s daily use. The use of mass spectrometry in particle analysis has not been attempted in this way before, but Wilkins has a history of innovating new techniques in the field of mass spectrometry. He was one of the first to introduce analytical Fourier-Transform Mass Spectrometry, a technique commonly used by analytical chemists worldwide, in 1980, and has won the 1997 American Chemical Society Franklin and Field Award for Outstanding Achievement in Mass Spectrometry for his efforts.

"Building this addition is like building a car by buying the parts and assembling it, except no one’s built this kind of machine before," he said.

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