NJIT chemists pave way for cheap, usable field test for polluted, toxic, water, air, food

03/23/04

Such nanoparticles abound now as trace chemicals in polluted air or water. Although they can be identified through current laboratory processes, the task is expensive and time consuming.

"We're hoping our research will pave the way to create a lab-on-a-chip that can identify trace pollutants in the field or at home," said Somenth Mitra, PhD, professor of chemistry at New Jersey Institute of Technology (NJIT). Eventually with the aid of such a versatile instrument any worker or homemaker will be able to whip out a cheap, throw-away sensor--just like the ones drug stores now sell for early pregnancy tests--and quickly learn if a toxic chemical is in the air, food or water.

Mitra will deliver his data at the American Chemical Society's 227th national meeting in Anaheim, CA, March 31, 2004 at 9:15 a.m. PST (12:15 p.m., E.S.T.). The name of the presentation is "Self-Assembly of nanoparticles For Preconcentration in Environmental Sensing Platforms." (Editors and reporters may call Sheryl Weinstein, 973-596-3436, to arrange in-person or telephone interviews with Dr. Mitra in California or when he returns to New Jersey.)

The growing need for inexpensive, portable monitoring devices has added new impetus to the miniaturization of chemical analysis systems. Miniaturization using nanotechnology yields many functional and economical benefits because of the reduction of a necessary sample size, the decrease in reagent consumption and the lower costs of mass production.

However, scientists cannot sacrifice results to create alternatives. "Yes, the idea behind our work is to miniaturize things or systems using nanotechnology," said Mitra. "But not at the expense of quality. To solve real-world environmental problems, the products must reach certain standards. They must be highly sensitive, selective, able to reproduce, exhibit a short response time as well as exhibit long-term stability."

Mitra's initial task has been to concentrate the materials he has been studying. "Since everything in the environment gets diluted, it is very hard to look for these chemicals without concentrating them," said Mitra.

Mitra has worked on creating two new methods of concentrating nanoparticles. One method concentrates pollutants in air. This method deposits nanoparticles from chemical vapors which in turn allow the tiny molecules to assemble themselves directly on the devices. "Doing this creates quantum interactions on the single wall carbon tubes and makes the analytes fall into lines," said Mitra.

The other approach which can also be used for airborne or liquid pollutants as well as food contaminants uses a chemical process to create a hard gel. The gel glues together the targeted nanoparticles to form themselves into distinct micro channels. Scientists often refer to this hard gel process as a "sol-gen synthesis." This latter approach also involves a solid phase extraction in micro channels through which fluid flows on nanoparticles.

Mitra's research interests include the development of analytical techniques and the applications of chemometrics to analytical and environmental problems. Current projects include: developing instrumentation and methods for continuous, on-line analysis of trace levels of organic pollutants in air and water, using gas chromatography, mass spectrometry, FTIR and total organic carbon analyzers. Scholarly journals and book publishers have published more than 50 of his peer-reviewed academic papers and two recent books: Environmental Chemical Analysis (CRC Press, New York, 1998) and Sample Preparation Techniques in Analytical Chemistry (John Wiley, New York, 2003). Four patents are in his name. He has also made more than 100 presentations to academic peers at scholarly conferences.

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