Instrument Automates Sampling of Atmospheric Pollutants
By automating the collection of data, the Particle-Into-Liquid-Sampler (PILS) developed at the Georgia Institute of Technology can measure particulate pollutants several times an hour, giving atmospheric scientists detailed time-dependent information not previously available. In a recent study, this ability to make frequent measurements revealed previously unknown peaks in the levels of two key pollutants.
"Chemists have made significant advances in measuring trace species," said Rodney Weber, assistant professor in Georgia Tech's School of Earth and Atmospheric Sciences. "We are applying those technologies to measure the composition of atmospheric particles. In combination with the ion chromatograph, this instrument provides some unique insights that could not be obtained before.
Developed by Weber and colleague Douglas Orsini with help from Brookhaven National Laboratory, the PILS system uses small quantities of steam to form water droplets on individual aerosol particles entering the instrument. The water droplets containing the dissolved aerosols can then be captured and analyzed by ion chromatography techniques to detect as many as 15 different chemical species.
The instrument can operate unattended for extended periods of time on the ground or in research aircraft, and can take samples as often as every four minutes.
Scientists analyzing airborne particulates had previously relied on filters that collected the aerosol particles over a long period of time, usually 24 hours. The particles were then removed from the filters and dissolved in water for ion chromatograph analysis. These long time-integrated measurements have provided the air quality data to study the effects of aerosols on human health.