NEWS OF THE WEEK ANALYTICAL
CHEMISTRY
CHEMISTRY ON THE FLY New technique couples airborne chemistry to sensitive Raman method
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HEMICAL REACTIONS
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curring in tiny airborne droplets can now be monitored with vibrational spectroscopy. The new molecule-specific method can detect minute quantities of organic compounds and may help advance efforts to miniaturize techniques in analytical chemistry Reducing the size of analytical instruments—and the samples analyzed with them—from conventional benchtop dimensions to miniature scale offers a number of advantages. For example, the change in scale can increase mass- and heat-transfer efficiencies, which in turn boosts reaction and separation efficiencies. But progress in microsystems has been moving slowly because only highly sensitive techniques can be used with tiny sample quantities. Now, two teams of researchers have shown that a high-sensitivity variation of Raman spectroscopy can be used to measure vibrational spectra of dilute sample solutions as droplets of the solution are suspended in air. One study used surface-enhanced Raman spectroscopy (SERS) to detect femtogram levels of test compounds such as 9aminoacridine in nanoliter-sized water droplets suspended in air via an ultrasonic lévitation technique [Anal Chem., published online April 4, http://dx.doi.org/10. 1021/ac0263081}. The work was carried out by analytical chemistry professor Bernhard Lendl and coworkers in the chemical analysis and vibrational spectroscopy group at Vienna University of Technology, Austria, together with scientists at BabesHTTP://WWW.CEN-ONLINE.ORG
Bolyai University in Romania and Lund University in Sweden. Taking advantage of the high sensitivity of the SERS technique requires depositing analyte molecules on roughened silver or o t h e r metal surfaces. Lendl and coworkers create such a surface on the fly by employing a microdispenser system to deliver streams of picoliter-sized droplets of silver nitrate and basic hydroxylamine solutions to the acoustic node of an ultrasonic levitator. T h e solutions react, forming nanoliter-sized airborne droplets containing colloidal silver particles. Then the group spikes the suspended par-
ACS
ticles with tiny quantities of analyte molecules and records Raman spectra. "This is a very exciting report," says Peter R. Griffiths, a chemistry professor at the University of Idaho, Moscow Griffiths, who is widely known for his innovations in vibrational spectroscopy methods, explains that there are few techniques that give moleculespecific information onpicoliter quantities of materials at submillimolar concentration. In another study m Analytical Chemistry {published online April 4, http://dx.doi.org/10.1021/ ac026302w], Stafian Nilsson and colleagues at Lund University AstraZeneca R&D in Sweden, and the University of Tennessee, Knoxville, describe similar techniques for studying crystallization in two model compounds: benzamide and indomethacin. The group detected two forms of each compound, suggesting an application for the new method in polymorph investigations.—
Lendl
MITCH JACOBY
NEWS
ACS Honors Public Service
M
embers of Congress and the ACS Board and their guests gathered on Capitol Hill on April 9 to honor Reps. Rush Holt (D-N.J.) and Judy Biggert (R-lll.) with ACS Public Service Awards. The awards—which were introduced by ACS Immediate Past-President Eli M. Pearce and presented by ACS President Eisa Reichmanis and President-Elect Charles P. Caseyrecognize non-ACS members who have made outstanding contributions to the development of public policy that benefit chemistry and the
sciences. Shown here (left to right) are Pearce, Holt, Biggert, Reichmanis, and Casey. Holt, a Ph.D. physicist, has worked hard to increase federal R&D funding. "We need help ... from scientists and engineers, people who can help illuminate the technological and scientific facets of the many issues that we deal with," Holt said. Biggert strongly supports increasing participation of women and minorities in science. She cosponsored successful legislation to increase the authorization amount for the Κ-Ί2 Math & Science Partnership Program. "I promise to continue to be a strong ad vocate for federal funding of scientific research for as long as I am in office," she said. She has high hopes for a bill she introduced that would increase funding for the Department of Ener gy's Office of Science. The awards cap a two-day legislative summit held by ACS to increase Congress' awareness of science issues.—AALOK MEHTA
C & E N / A P R I L U , 2003
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