Real-time Detection of Gaseous Chlorinated Paraffins at Multiple Field Sites with Chemical Ionization Mass Spectrometry

DANIEL KATZ, Bri Dobson, Harald Stark, Manjula Canagaratna, Mitchell Alton, Douglas Worsnop, Eleanor Browne, University of Colorado Boulder & CIRES

     Abstract Number: 438
     Working Group: Aerosol Chemistry

Abstract
Chlorinated paraffins (CPs) are polychlorinated alkyl compounds which are considered persistent organic pollutants due to their toxicity to humans and wildlife, long lifetimes, and ubiquity in the environment. CPs are synthetic compounds with a wide range of industrial applications and are typically produced as a mixture of compounds with a range of carbon numbers and degrees of chlorination. CPs are released to the environment throughout their production, use, and disposal lifecycle. While much of the scientific investigation of CPs has focused on short chain chlorinated paraffins (SCCPs), measurements of medium chain chlorinated paraffins (MCCPs) are scarce. Increased regulation of SCCPs, including under the Stockholm Convention, is expected to precipitate an increase in the production of MCCPs as replacements for SCCPs. As MCCPs account for a larger portion of CP production, understanding the cycling and fates of MCCPs in the environment will be increasingly important. Measurements of atmospheric CPs have typically relied on polyurethane foam samplers which require long sample collection times and obscure the temporal behavior of CPs in the ambient air. Here, we present the first real-time detection of gas-phase CPs using nitrate ion chemical ionization mass spectrometry (NO3-CIMS). The detected CPs have a range of carbon and chlorine atoms in their formulas. Due to the number of carbon atoms in the detected CPs, we classify them as MCCPs. Ambient measurements from multiple disparate field sites will be presented. We show that the diel behavior of MCCPs is explained in part by partitioning of MCCPs between the particle phase and gas phase. The presence of MCCPs in the particle phase suggests they may be transported over long distances in the atmosphere. The predicted particle fractions of the detected compounds vary with alkyl chain length and degree of chlorination, which impacts the lifetimes and fates of different MCCP compounds.