AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Calibration of the Laser Induced Incandescence-Mass Spectrometric Analyzer (LII-MS) Using Polydisperse Aerosol Particles
CUIZHI SUN, Nobuyuki Takegawa, Tokyo Metropolitan University
Abstract Number: 40 Working Group: Instrumentation and Methods
Abstract Online measurements of chemical composition provide useful insights into the sources and formation processes of ambient aerosols. Routine calibrations of online aerosol instruments are important for assessing the performance of the instruments during field measurements. The choice of materials and optimal size distributions for calibration particles can vary depending on the detection methods and size-dependent collection efficiency of the instruments. The combination of a differential mobility analyzer (DMA) and a condensation particle counter (CPC) is a reliable, conventional method for calibrations. However, the use of a radioactive source as a neutralizer sometimes requires special cares when deploying a DMA for filed measurements because of regulation for using radioactive materials, especially in Japan. The purpose of this study is to propose a simple calibration method without using a DMA and CPC for the recently developed laser induced incandescence-mass spectrometric analyzer (LII-MS; Miyakawa et al., AST, 2014). Polydisperse aerosol particles of some selected chemical compounds are generated by atomizers (Model 226, TOPAS). The size distribution of polydisperse aerosols can be optimized by adjusting the solution concentration, atomizer flow rate, and dilution air. The LII section is used as an optical particle counter for estimating the mass concentration of polydisperse aerosol particles. The accuracy of the LII sizing and counting efficiency is critical for this method and regularly checked by measuring pulse height distributions for polystyrene latex (PSL) particles. Here we present the results for ammonium sulfate (AS), ammonium nitrate (AN), and potassium nitrate (PN). A comparison of this method with the conventional DMA-CPC method in laboratory and its potential uncertainties are presented and discussed.