May 15, 2000 MANHATTAN -- An article in the most recent issue of Chemistry and Industry magazine describes a powerful technique for analyzing a wide variety of samples without destroying them in the process. Authors of the article, Kansas State University chemist David Wetzel and John A. Reffner, technical director at SensIR in Danbury, Conn., are leaders in the field of infrared microspectroscopy.
The invited article by the two scientists, "More information from less sample," describes how the new technique helped solve the bombing of the World Trade Center, using only fragments of debris collected at the scene. Infrared microspectroscopy combines a special infrared microscope, infrared spectrometer and computer. This instrumentation makes it possible to analyze the localized chemical content of extremely small specimen -- single cells, single fibers, single crystals, and botanical parts. The technical advance eliminated the need to grind up a sample or stain it. Instead, slicing it "thin enough" -- to 1/10th the thickness of a human hair -- is all that's needed to probe its chemistry.
Select wavelengths of infrared radiation that strike the target sample are either absorbed or transmitted by the molecules, thus providing a chemical signature. That infrared signature tells an analyst what's present and how much. Being able to achieve spatial resolution has been a long-time goal of scientists, and the microscope pinpoints the target of only a few microns. By analyzing a sample in a grid pattern, a map of localized chemistry of the molecules is developed that can be superimposed over the visible physical microstructure under study.
This rapidly emerging technology has increasing applications for biological and other research. The tiniest particle can be analyzed -- a paint chip from a hit and run case to a single red blood cell to study rare blood disorders.
"Even a single cell in the cross-section of a wheat kernel, surrounded by cell walls and tissue, can be isolated with image masks and its unique infrared absorption spectra recorded for analysis," the authors say.
Wetzel has worked at the cutting edge of this technology since the modern infrared microscope was developed and patented in 1989. Almost immediately, Wetzel carried sectioned wheat samples to the inventor's labs for analysis on the new instruments, thus becoming one of the first researchers in the world to test its capability for analyzing biological materials.
The quality of the data from those first wheat experiments became the basis for a scientific presentation, and subsequent scientific publication.
According to Wetzel, inside a wheat kernel or other tissues, there are localized miniature biochemical factories with raw material, intermediate material and end products. "With an infrared microspectrometer, we could begin to see how each factory is working, and analyze it on the spot," he explained.
For more information contact David Wetzel at K-State's department of grain science and industry, Microbeam Molecular Spectroscopy Lab, department of grain science and industry Microbeam Molecular, at 785-532-4094 (office), 785-539-2509 (home) or e-mail Dwetzel@ksu.edu; or at SensIR Technologies, 203-207-9700.
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