Health Assessment Document for Diesel Emissions - NSCEP | US ...

1 solvent. and this ratio was probably the result of the presence of both oxygenated organic
2 compounds and inorganic sulfates in the extracted mass.
3
4 2.3.2.3.1. Extraction and fractionation techniques. A variety of solvents and extraction
5 techniques have been used in the past for the separation of organic compounds from diesel
6 particles (Levsen, 1988). Although the reports on the extraction efficiencies are in part
7 contradictory, it appears that Soxhlet extraction and the binary solvent system composed of
8 aromatic solvent and alcohol gave the best recovery ofPAHs, as determined by 14C-B[a]P . 9 (benzo[ a ]pyrene) spiking experiments (Schuetzle and Perez, 1981 ). Direct chemical analysis of
1 0 the entire extractable fraction of diesel particulate matter is not generally possible because a large
11 number of compounds of different polarity_ are present. The separation of diesel particulate
12 organic matter (POM) into various fractions according to chemical functionalities is a necessary
13 preliminary step to chemical identification of individual compounds. Open-column liquid
14 chromatography (LC) and liquid-liquid separation procedures have been the most widely used
15 fractionation methods (Lee and Schuetzle, 1983). Open-column LC is very often followed by
16 normal-phase high-performance liquid chromatography (HPLC) if the identification of less
17 abundant components is required.
18
19 2.3.2.3.2. Chemical composition. Table 2-7 lists the general classes of extractable organic
·20 compounds identified in POM from combustion emissions, including diesel emissions.
21 Liquid chromatography methods usually divide the complex environmental mixtures of
22 organic compounds ·into nonpolar, moderately polar, and polar fractions. This separation is
Table 2-7. Classes of organic compounds identified in particulate-phase
combustion emissions
Hydrocarbons
Derivatives• of hydrocarbons
Polycyclic aromatic hydrocarbons (PAHs)
Derivatives of PAH
Multifunctional derivatives of P AH
Heterocyclic compounds
Derivatives of heterocyclics
Multifunctional derivatives of heterocyclic compounds
'Derivatives include acids, alcohols, aldehydes, esters, ketones, nitrates, and sulfonates.
Source: Adapted from Schuetzle ( 1988).
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