AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Application of Positive Matrix Factor Analysis in Heterogeneous Kinetics Studies: OH Initiated Oxidation of Organophosphate Flame Retardants in PM
JOHN LIGGIO, Yongchun Liu, Shao-Meng Li, Environment Canada
Abstract Number: 51 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Organophosphate flame retardants (OFRs) are widely used in North America and Europe to depress the formation of flames in various commercial products despite the inherent toxicity of some of these compounds. These compounds are increasingly being measured in ambient particulate matter around the globe, suggesting that they are rather persistent in the atmosphere. However, there remains very little kinetic data on the heterogeneous processing of these compounds on ambient PM. In the current study, a mixed-phase relative rate approach for determining organic aerosol particle heterogeneous reaction kinetics been improved by performing Positive Matrix Factor (PMF) analysis of Aerosol Mass Spectrometry data. PMF analysis thereby removes the influence of m/z fragments from reaction products on the reactant signals used to derive kinetics. To demonstrate the advantages of this approach, the heterogeneous reaction between OH radicals and citric acid (CA) and several organophosphate flame retardant compounds was investigated using a photochemical flow tube coupled to a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS). The measured heterogeneous rate constant (k2) for particulate-phase organophosphates (TPhP, TDCPP, and TEHP), were found to be greater than previously reported utilizing individual m/z fragments. The effect of particle size, relative humidity, and the internal/external mixture of OFRs with other ambient organics is also investigated and found to have a significant effect on the ultimate particle phase lifetime of these, and presumably other toxic PM components.