Quartz Crystal Microbalances Enable New Microscale Analytic Technique
A new chemical analysis technique developed by a research group at the National Institute of Standards and Technology (NIST) uses the shifting ultrasonic pitch of a small quartz crystal to test the purity of only a few micrograms of material. Since it works with samples close to a thousand times smaller than comparable commercial instruments, the new technique should be an important addition to the growing arsenal of measurement tools for nanotechnology, according to the NIST team.
As the objects of scientific research have gotten smaller and smaller—as in nanotechnology and gene therapy—the people who worry about how to measure these things have been applying considerable ingenuity to develop comparable instrumentation.* This new NIST technique is a riff on thermogravimetric analysis (TGA), an imposing name for a fairly straightforward concept. A sample of material is heated, very slowly and carefully, and changes in its mass are measured as the temperature increases. The technique measures the reaction energy needed to decompose, oxidize, dehydrate, or otherwise chemically change the sample with heat.
TGA can be used, for example, to characterize complex biofuel mixtures because the various components vaporize at different temperatures. The purity of an organic sample can be tested by the shape of a TGA plot because, again, different components will break down or vaporize at different temperatures. Conventional TGA, however, requires samples of several milligrams or more of material, which makes it hard to measure very small, laboratory-scale powder samples—such as nanoparticles—or very small surface chemistry features such as thin films.
What's needed is an extremely sensitive "microbalance" to measure the minute changes in mass. The NIST group found one in the quartz crystal microbalance, essentially a small piezoelectric disk of quartz sandwiched between two electrodes. An alternating current across the electrodes causes the crystal to vibrate at a stable and precise ultrasonic frequency—the same principle as a quartz crystal watch. Added mass (a microsample) lowers the resonant frequency, which climbs back up as the microsample is heated and breaks down.
In a new paper.** the NIST materials science group demonstrates that their microbalance TGA produces essentially the same results as a conventional TGA instrument, but with samples about a thousand times smaller. They can detect not only the characteristic curves for carbon black, aluminum oxide and a sample organic fluid, but also the more complex curves of mixtures.
"We started this work because we wanted to analyze the purity of small carbon nanotube samples," explains analytical chemist Elisabeth Mansfield. More recently, she says, they've applied the technique to measuring the organic surface coatings biologists put on gold nanoparticles to modify them for particular applications. "Measuring how much material coats the particles surface is very hard to do right now," she says, "It will be a really unique application for this technique."
The prototype apparatus requires that the frequency measurements be made in a separate step from the heating. Currently, the team is at work integrating the microbalance disks with a heating element to enable the process to be simultaneous.
* See, for example, "Micro Rheometer is Latest Lab On a Chip Device" in NIST Tech Beat, Aug. 31, 2010, www.nist.gov/public_affairs/tech-beat/tb20100831.cfm#rheometer.
** E. Mansfield, A. Kar, T.P. Quinn and S.A. Hooker. Quartz crystal microbalances for microscale thermogravimetric analysis. Anal. Chem. Article ASAP, published online Nov. 16, 2010. DOI: 10.1021/ac102030z
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New Guidance Issued for First Responders Collecting Suspected Biothreat Agents
Suspicious packages and powders have triggered more than 30,000 responses by U.S. law enforcement agencies across the country since 2001. These events are expensive, time-consuming and potentially dangerous. To help first responders at all levels of government deal safely and more effectively with suspected biothreat agents, the National Institute of Standards and Technology (NIST) and a broad team of federal, state and local agencies and other organizations worked together to update an existing standard for sample collection and develop overall guidance for when to collect a sample and how to coordinate with other agencies and organizations.
The original standard protocol for collecting and preserving samples of suspicious powders was developed and published in 2006 at the request of the U.S. Department of Homeland Security by a multiagency team coordinated by NIST and AOAC (Association of Analytical Communities) International. It outlined a two-step process for collecting bulk samples of suspicious powder from a solid surface such as a desktop or tile, and the collection of residual material with swabs for use in field evaluation.
Recommendations for developing new, general guidelines to facilitate sample collection and coordination with a receiving laboratory came from members of two focus groups from the first responder community. With expertise in sample collection and forensic research, and unique relationships with government agencies and stakeholder communities, NIST, together with a coalition of federal, state and local agencies and stakeholder organizations, was able to revise the standard and develop new guidance.
Because many of the organizations involved in responding to these incidents have different concerns and needs for sample collection, broad acceptance of the new standard and guidance is critical. For example, first responders initially assess a situation by performing a risk assessment in coordination with public health response, including the Centers for Disease Control and Prevention, and law enforcement, including the Federal Bureau of Investigation. The primary concern of this assessment is protecting the public while preserving the chain of custody if the incident is a confirmed biothreat event and material is used as evidence in a criminal investigation.
“The new guidance explains that first response agencies should do the legwork now to establish relationships they will need in the event of an incident,” says Jayne Morrow, an environmental engineer at NIST who led the revision project. “For example, it provides recommendations regarding who should be at the planning table, and it even recommends creating a laminated card of phone numbers for expert support to enable first responders to effectively address one of these situations.
“What first responders tell us they like about this guidance is that it’s appropriate for any jurisdiction, regardless of its size and resources,” says Morrow. “And the key message is that, through response coordination and communication, we can effectively deal with an event in a timely and appropriate manner.”
The revised protocol, “Standard Practices for Bulk Sample Collection and Swab Sample Collection of Visible Powders Suspected of Being Biothreat Agents from Nonporous Surfaces” (E2458-10) and the “Standard Guide for Operational Guidelines for Initial Response to a Suspected Biothreat Agent” (E2770-10) are now available from ASTM International, a provider of international voluntary consensus standards.
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2010 Baldrige Award Winners Announced
U.S. Commerce Secretary Gary Locke yesterday named seven organizations as recipients of the 2010 Malcolm Baldrige National Quality Award, the nation’s highest Presidential honor for performance excellence through innovation, improvement and visionary leadership. This marks the first year that three small businesses have been selected at one time and only the second instance in the Award’s 23-year history that a total of seven organizations are being honored.
The 2010 Baldrige Award recipients (and categories) are:
The 2010 Baldrige Award recipients were selected from a field of 83 applicants. All of the applicants were evaluated rigorously by an independent board of examiners in seven areas: leadership; strategic planning; customer focus; measurement, analysis and knowledge management; workforce focus; process management; and results.
The only Presidential Award for performance excellence, the Baldrige Award was established by Congress in 1987 to enhance the competitiveness and performance of U.S. businesses. Manufacturers, service companies, small businesses, education institutions, healthcare organizations, and nonprofit organizations such as charities, trade and professional associations, and government agencies are eligible to receive the award. The award promotes excellence in organizational performance, recognizes the achievements and results of U.S. organizations, and publicizes successful performance strategies. Since 1988, 86 organizations have received the Baldrige Award. It is named after Malcolm Baldrige, the 26th Secretary of Commerce.
The Baldrige Performance Excellence Program is managed by the Commerce Department’s National Institute of Standards and Technology (NIST) in conjunction with the private sector. The program raises awareness about the importance of performance excellence in driving the U.S. and global economy; provides organizational assessment tools and criteria; educates leaders in businesses, schools, health care organizations, and government and nonprofit agencies about the practices of best-in-class organizations; and recognizes national role models by honoring them with.
For more details, read today’s news announcement, “Seven U.S. Organizations Honored with the 2010 Baldrige National Quality Award” at www.nist.gov/baldrige/baldrige_recipients2010.cfm.
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Three NIST Scientists Earn Presidential Early Career Awards
Three NIST researchers have been chosen to receive Presidential Early Career Awards for Scientists and Engineers (PECASE), the highest honor bestowed by the U.S. government on science and engineering professionals in the early stages of their independent research careers.
Named by President Obama, the NIST scientists were among 85 young researchers selected from universities and federal research organizations around the nation. The winners were recognized for the great promise of their early career accomplishments in science and engineering. The three NIST awardees are:
R. David Holbrook, Jr., chemical engineer in the Surface and Microanalysis Science Division, whose research interests include the behavior of engineered nanoparticles and microanalysis of environmental samples.
Daniel S. Hussey, physicist in the Physical Measurement Laboratory, who specializes in applying and extending the technique of neutron imaging at the NIST Center for Neutron Research.
Ian B. Spielman, NIST physicist and a fellow at the NIST-University of Maryland Joint Quantum Institute, who uses highly controlled ultracold atoms, trapped in crystals of laser light, to create quantum materials that shed light on problems in solid-state physics.
PECASE awardees are selected for their pursuit of innovative research at the frontiers of science and technology and their commitment to community service as demonstrated through scientific leadership, public education or community outreach.
Read the presidential announcement at www.whitehouse.gov/administration/eop/ostp/pressroom/11052010
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