Measurement of carbonaceous aerosols: validation and comparison of a solvent extraction–gas chromatographic method and a thermal optical transmittance method

Abstract

A solvent extraction–gas chromatographic method was developed for the measurement of four classes of solvent-extractable organic compounds (SEOC), viz., aliphatic hydrocarbons, polynuclear aromatic hydrocarbons, fatty acids and alkanols, in ambient carbonaceous aerosols. The selectivity and recovery of the method using different solvents commonly used in the analysis of SEOC was evaluated. The composition of SEOC in aerosol and urban dust samples was found to vary with the choice of solvent. Such variation was not observed in filters spiked with standards of SEOC. The developed method was validated by the analysis of reference urban dust SRM 1649a from the National Institute of Standards and Technology. The concentrations of selected polynuclear aromatic hydrocarbons in the reference dust were found to fall within the certified and reference concentrations. The thermal characteristics of aerosol samples collected in an urban area of Hong Kong and the four classes of identified SEOC were also studied using a thermal optical transmittance (TOT) method as specified in NIOSH Method 5040. Correlations were made to compare the method-dependent SEOC content obtained by the solvent extraction method and the results for total carbon, organic carbon and elemental carbon obtained by the TOT method.