AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Interpretation of Regression Parameters for Quantification of Organic Aerosol Mass Components with Infrared Transmission Spectra
SATOSHI TAKAHAMA, Ann Dillner, Ecole Polytechnique Federale de Lausanne, Switzerland
Abstract Number: 35 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract In this work, we present a comparison of two regression approaches for quantitative analysis of vibrational spectra for laboratory-generated aerosols and particulate matter collected on IMPROVE network filters. Infrared spectroscopy provides a method for non-destructively analyzing the organic functional group abundance and total organic aerosol mass (OM) on off-line filters with high mass recovery (Russell, 2003).
The first method for quantification considered, explicit band-fitting (Takahama et al., 2013), proceeds by sequential application of non-linear least squares regression to apportion spectrum extinction to substrate (PTFE) interference and molecular bond absorption according to separate constraints provided by laboratory standards. The second method, partial least squares regression (Coury and Dillner, 2008; Ruthenburg et al., 2014), trains a set of regression parameters on laboratory standard mixtures by projection to and rotation of latent factors to maximize predictive power. We will discuss the relative merits each method and also present a mechanistic interpretation of regression parameters generated mathematically from the partial least squares calibration, and use this interpretation to additionally assess our capability for prediction of thermal optical reflectance OC, EC, and TC from infrared absorption spectra.
Coury, C, Dillner, A.M. (2008). A Method to Quantify Organic Functional Groups and Inorganic Compounds in Ambient Aerosols using Attenuated Total Reflectance FTIR Spectroscopy and Multivariate Chemometric Techniques, Atmospheric Environment, 41, 9309-9323.
Ruthenburg, T.C., Perlin, P.C., Liu, V., McDade, C.E., Dillner, A.M. (2014). Determination of Organic Mass and Organic Mass to Organic Carbon Ratios by Infrared Spectroscopy with Application to Selected Sites in the IMPROVE Network. Atmospheric Environment 86, 47-57, http://dx.doi.org/10.1016/j.atmosenv.2013.12.034.
Takahama, S., Johnson, A., Russell, L.M. (2013). Quantification of Carboxylic and Carbonyl Functional Groups in Organic Aerosol Infrared Absorbance Spectra. Aerosol Science and Technology 47, 310–325, doi:10.1080/02786826.2012.752065