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MEETING NEWS
A portable mass spectrometer capable of performing underwater analyses could play an important role in policing U.S. coastal waters, ports, and harbors for illicit chemical spills unleashed by terrorists or accidents, say researchers from the University of South Florida (USF). They envision outfitting unmanned, underwater vehicles with an MS device currently under development for environmental monitoring and oceanographic research to serve as a constant monitoring network for chemicals of concern. The primary advantage “is that you can actually get real-time information, allowing you to map out chemical plumes in lakes and coastal systems or give you a warning when something exceeds a certain threshold,” explains R. Timothy Short, a sensor development engineer at USF. He admits that their existing unit cannot yet detect the chemical and biological warfare agents that homeland security experts are concerned about. However, alternative membrane interfaces—in particular, an automated solid-phase extraction interface—should allow them to detect some of the more polar compounds making up chemical warfare agents, he says. Short and colleagues have constructed
systems based on both linear quadrupole and ion trap mass analysis; a polydimethylsiloxane membrane interface provides parts-per-billion detection limits for various volatile organic compounds, including toluene, benzene, and chloroform, and dissolved gases such as methane. Other groups pursuing similar research include the Massachusetts Institute of Technology, NASA’s Jet Propulsion Laboratory, and the University of Hawaii. The USF researchers have used the systems for both pollution monitoring and basic marine science, deploying them mostly in shallow waters on small or unmanned vehicles. They’re working on extending the system’s analysis capability down to depths of 200 m. Other potential applications include industrial outfall management, water intake protection, and underwater oil and gas exploration, says Robert Haydock of Applied Microsystems Ltd., which has licensed the technology from USF. The device is particularly powerful for outfall and intake control because of its capability of monitoring for multiple contaminants on a real-time basis, allowing managers to take immediate steps to protect a facility or correct operations at a petrochemical plant,
UNIVERSITY OF SOUTH FLORIDA, CENTER FOR OCEAN TECHNOLOGY
Underwater MS for defense?
An unmanned vehicle with a mass spectrometer on the underside maps chemical plumes.
for example, before contaminants cause widespread harm in the environment. In the case of undersea exploration, Haydock foresees the device being used to sniff out hydrocarbon vents or seeps and provide guidance for exploratory drilling. For this application, however, researchers would have to expand the system’s analysis capability down to 1500–2000-m depths, he notes. Other enhancements under development include increasing the number of chemicals the unit can detect and reducing its size from the current standard configuration (40 in. long and 7.5 in. diam). a —Kris Christen
GOVERNMENT AND SOCIETY Lowering the bar on perchlorate detection The U.S. Environmental Protection Agency (EPA) decision in July not to move forward with developing a drinking water regulation for perchlorate caught many by surprise, given the concern over potential health effects at low concentrations and possible widespread environmental contamination. A major factor in this decision, agency officials say, is the need to improve low-level detection methods. Perchlorate is the primary ingredient used in the manufacture of solid propellant for rockets, missiles, and fireworks, and it is a high-priority substance on EPA’s list 494 A
of unregulated contaminants of concern, which is known as the Contaminant Candidate List. The agency has confirmed perchlorate releases in ground- and surface waters in more than 20 states and recommended a preliminary drinking water limit of 1 ppb in 2002. The National Academy of Sciences is reviewing the risk assessment on which this draft limit is based. Perchlorate has also been found in lettuce irrigated with water contaminated by rocket fuel in California and Arizona, and a study in Environmental Science & Technology (2003, 37, 4979– 4981) turned
A N A LY T I C A L C H E M I S T R Y / D E C E M B E R 1 , 2 0 0 3
up perchlorate in samples of supermarket milk in Texas. Such findings, as well as the uncertainty surrounding the severity of health effects at various concentrations, are driving the development of selective, highly sensitive detection methods. Andrew Eaton of MWH Laboratories, a coauthor of EPA’s Method 314, says that this method, which uses ion chromatography (IC) with a conductivity detector and has a minimum reporting limit of 4 ppb, is the only one approved for perchlorate monitoring. It was developed in 1999 under EPA’s Unregulated Contami-
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nant Monitoring Rule (UCMR). Because of perchlorate’s high visibility as an environmental contaminant, however, “It is critical that methods be able to reliably and accurately provide quantitative data at levels down to below 1 ppb,” Eaton says. He and his colleagues have been trying to modify Method 314 to reduce the reporting limit without significantly increasing the cost of the analysis. Using various sample treatment techniques, coupled with modifying the IC operation, they’ve been able to accurately quantify perchlorate in the 0.5-ppb range, provided that the total dissolved solids (TDS)— chloride, sulfate, and bicarbonate—contained in the matrices are
