Fireworks linger long after colors fade.For scientists at the University of California, Riverside The University of California, Riverside, commonly known as UCR or UC Riverside, is a public research university and one of ten campuses of the University of California system. , the Fourth of July Fourth of July, Independence Day, or July Fourth, U.S. holiday, commemorating the adoption of the Declaration of Independence. Celebration of it began during the American Revolution. means more than picnics, pyrotechnics pyrotechnics (pī'rōtĕk`nĭks, pī'rə–), technology of making and using fireworks. Gunpowder was used in fireworks by the Chinese as early as the 9th cent. , and patriotism. It gives them an opportunity to do some chemistry. During a fireworks fireworks: see pyrotechnics. fireworks Explosives or combustibles used for display. Of ancient Chinese origin, fireworks evidently developed out of military rockets and explosive missiles and accompanied the spread of military explosives westward to show on July 4, 1995, Kimberly A. Prather and her colleagues first tested a method they had developed to monitor airborne particles. Called aerosol time-of-flight mass spectrometry This article is about the mass spectrometry technique. For other uses, see time-of-flight. Time-of-flight mass spectrometry (TOF-MS) is method of mass spectrometry in which ions are accelerated by an electric field of known strength. , the technique rapidly provides information on both particle size Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. and chemical composition. Other methods measure only one or the other, says Prather. She and her coworkers monitored the air outside their lab from July 3 to July 7. Most of the particles they detected probably came from a fireworks display on Mount Rubidoux, about 3 miles west, Prather says. The fireworks show was an ideal test source of particles because it had a well-defined start time and location. Also, "it had a distinctive [chemical] signature, so we could pick it out easily," Prather adds. The peak number of particles arrived the morning of July 5, about 12 hours after the start of the show. The number didn't trail off significantly until 7 hours after that, and particles were still detected as late as July 19. The group's findings appear in the May 15 Analytical Chemistry. Most other techniques rely on collecting particles on filters, which can take hours. The material must then be sent away for expensive and time-consuming analysis. "There's no way to say what's out there now," Prather says. The ability of their technique to give immediate results makes it good for applications such as detecting biological and chemical warfare. The group is testing new, portable versions of the device now. "This is a demonstration of the ability to pick out one modest source among a complicated mix of sources," says Glen R. Cass of the California Institute of Technology California Institute of Technology, at Pasadena, Calif.; originally for men, became coeducational in 1970; founded 1891 as Throop Polytechnic Institute; called Throop College of Technology, 1913–20. in Pasadena. Concern over the health effects of particles (SN: 5/6/89, p. 277) and the Environmental Protection Agency's upcoming standards on atmospheric particles indicate "there will be more interest in measuring them," Cass says. |
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