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

1 achieved by using specific solvents (or solvent mixtures) for the elution of compounds from
2 chromatographic columns. Schuetzle and co-workers ( 1985) proposed that standard chemical
3 compounds be selected for establishing reference points for the fractionation of diesel POM into
4 nonpolar, moderately polar, and polar fractions by normal-phase HPLC. They proposed that the
5 elution of 1-nitronaphthalene would define the end of the elution of nonpolar compounds and the
6 beginning of the moderately polar fractions. In a similar way, 1,6-pyrene quinone would define
7 the end of elution of moderately polar compounds and the beginning of the polar region.
8 For diesel engine emissions, ::::57% of the extracted organic mass is contained in the
9 nonpolar fraction (Schuetzle, 1983). About 90% of this fraction consists of aliphatic
_1 0 hydrocarbons from approximately cl4 to about c40' with a carbon number maximum at c22 to c26
11 (Black and High, 1979; Pierson et al., 1983). Polycyclic aromatic hydrocarbons and alkyl-
. 12 substituted P AH account for the remainder of the nonpolar mass.
13 The moderately polar fraction ( ::::9% w/w of extract) consists mainly of oxygenated P AH
14 species and nitrated P AHs. The polar fraction (:::: 32% w/w of extract) is composed mainly of
15 carboxylic and dicarqoxyli-c acids ofPAH, hydroxy-PAH, hydroxynitro-PAH, nitrated
16 N-containing heterocyclic compoimds, etc. (Schuetzle, 1983; Schuetzle et al., 1985).
17 Limited recovery studies have shown that there is little degradation or loss of diesel POM
18 on the HPLC column. More than 90% of the mass and 70% to 100% of the Ames
19 S. typhimurium-active material injected onto the column have been recovered (Schuetzle et al.,
·20 1985).
21
22 2.3.2.3.3. Polycyclic aromatic hydrocarbons. Particle-bound P AHs and their derivatives
23 (mainly nitrated PAH) attracted considerable attention relatively early because of their mutagenic
24 and, in some cases, carcinogenic properties (see, for example, National Research Council, 1982).
25 The most widely used methods ofPAH analysis included thin layer chromatography (TLC),
26 capillary gas chromatography (GC), gas chromatography/mass spectrometry (GC/MS), and
27 HPLC with ultraviolet or fluorescence detection (Levsen, 1988). Table 2-8 lists the P AHs and
28 thioarenes identified and quantified by GC/MS in three LDD particulate matter extracts (Tong
29 and Karasek, 1984). Data listed in this table reveal the presence of a large number of alkyl
30 derivatives of P AH, which are sometimes more abundant than the parent P AH.
31 Table 2-9 compares the emission rates of several representative P AHs from HDD, LDD,
32 and gasoline (with and without catalytic converter) engines.
33
34 2.3.2.3.4. Nitrated polycyclic aromatichydrocarbons. Nitro-PAHs (nitroarenes) have been
35 shown to be present in diesel particulate extracts, though in much lower concentration than the
36 . · parent PAHs (Schuetzle et al., 1981, 1982; Paputa-Peck et al., 1983). Because many nitroarenes
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