ATMOSPHERIC CHEMISTRY

Measuring Particle Composition

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Science  02 Nov 2001:
Vol. 294, Issue 5544, pp. 961
DOI: 10.1126/science.294.5544.961b

Earth's atmosphere contains many different types of particles, from natural substances such as sea salt to anthropogenic by-products such as soot. These particles play important roles in climate—for example, by seeding or suppressing rain or by consuming protective ozone. Atmospheric particles also contribute to health problems in densely populated areas. Detailed measurements of particle compositions, sizes, and distributions would be useful, but particle morphologies and compositions are complex and evolve with time.

Aerosol mass spectrometry has been used to monitor the composition of individual particles in real time, but the techniques have required careful calibration, and quantitative results have been difficult to obtain. Now, Reents and Schabel describe quantitative mass spectrometric determination of the atomic composition of individual particles, without the need for calibration. High laser power density converts the entire particle into atomic cations whose ion signals reflect the composition of the particle, and helium, instead of argon, is used as the carrier gas. This enables them to achieve an accuracy of 20% for the major components of multicomponent particles.—JU

Anal. Chem., 10.1021/ac010436c.

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