Trescott E. Jensen

Polar polynuclear aromatic hydrocarbon derivatives in extracts of particulates: Biological characterization and techniques for chemical analysis

A protocol incorporating the concept of “bioasssay directed chemical analysis” has been developed for the analysis of polar polynuclear aromatic hydrocarbon (polar-PAH) derivatives in particulate matter samples. As an example of the protocol, results and are presented for a National Bureau of Standards (NBS) candidate standard reference diesel particulate material (SRM 1650). Good recovery of mutagenicity and mass suggests that compound decomposition/conversion was minimized. Identification of polar-PAH derivatives was undertaken for liquid chromatographic fractions of a heavy-duty diesel particulate extract that were found to contain a large portion of the total extract mutagenicity. Hydroxy-PAH, hydroxy-nitro-PAH, PAH-quinones, and nitrated heterocyclics were tentatively identified in the polar fractions of the diesel extract. The compounds of most interest at this time, because of their relatively high mutagenicity, are multifunctional nitrated-PAH (e.g., hydroxy-nitro-PAH) and nitrated-heterocyclics. Several new techniques are described that could greatly facilitate the identification of specific isomers of polar mutagens.

Advanced Emission Speciation Methodologies for the Auto/Oil Air Quality Improvement Research Program - I. Hydrocarbons and Ethers

An analytical method for the determination of hydrocarbon and ether emissions from gasoline-, methanol-, and flexible-fueled vehicles is described. This method was used in Phase I of the Auto/Oil Air Quality Improvement Research Program to provide emissions data for various vehicles using individual reformulated gasolines and alternate fuels. These data would then be used for air modeling studies. Emission samples for tailpipe, evaporative, and running loss were collected in Tedlar bags. Gas chromatographic analysis of the emissions samples included 140 components (hydrocarbons, ethers, alcohols and aldehydes) between C1 and C12 in a single analysis of 54-minutes duration. Standardization, quality control procedures, and inter-laboratory comparisons developed and completed as part of this program are also described. (Copyright (c) 1992 Society of Automotive Engineers, Inc.).

Mutagenicity studies of p-substituted benzyl derivatives in the Ames Salmonella plate-incorporation assay

The mutagenicity of 24 benzyl derivatives, containing a variety of substituents and leaving groups, were assayed in strain TA100 using the Ames plate-incorporation assay. p-Nitrobenzyl chloride (12 000 revertants/mumole), p-nitrobenzyl tosylate (6100 revertants/mumole), and p-acetoxybenzyl chloride (100 revertants/mumole) were mutagenic; none of the remaining 21 compounds were mutagenic. p-Nitrobenzyl chloride was also found to be mutagenic in strain TA98 (700 revertants/mumole), but not in strain TA98NR (a strain deficient in nitro reductase activity). p-Acetoxybenzyl chloride was nonenzymatically hydrolyzed to p-hydroxybenzyl alcohol and p-acetoxybenzyl alcohol. These findings suggest that nitrobenzyl derivatives were mutagenic due to nitro reductive metabolism and that p-acetoxybenzyl chloride was mutagenic due to the intermediate formation of p-hydroxybenzyl chloride during the hydrolysis of p-acetoxybenzyl chloride.

GC/MS-FID analysis of BSTFA derivatized polar components of diesel particulate matter (NBS SRM-1650) extract

SummaryHydroxy and acid compounds, present in the polar HPLC fraction number 8 from the NBS-SRM 1650 (diesel particulate extract) were derivatized with N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA) to form the trimethylsilane (TMS) derivatives. This improved the gas-chromatographic separation to give an improved characterisation using GC-MS. TMS derivatives were only observed in the acid extract of an aliquot of HPLC fraction number 8 which had undergone an acid-base fractionation. A number of previously unidentified compounds in fraction 8 could be characterised using mass spectroscopy. Ion mass chromatograms, recorded at m/z 73, 89 and 147 were correlated with the total ion current (TIC) to identify derivatized compounds. Only single, two and three ring derivatized aromatics were observed. The compounds identified in this polar fraction of the extract included p-nitrophenol, benzoic acid, hydroxy-benzoic acids, hydroxy-benzaldehyde, hydroxy-phthalimide, benzene dicarboxylic acids, naphthalene dicarboxylic acids, anthracene/phenanthrene dicarboxylic acids and, for some of these, the C1 to C3 alkyl homologues. Several methyl esters were also observed including biphenyl dimethyl ester and benzene trimethyl ester.

1-Nitropyrene in used diesel engine oil

It has been shown that engine oil may contribute 16 to 80 percent of the mass of organic-solvent-extractable particulate matter in diesel engine exhaust. This raises the possibility that the 1-nitropyrene in the exhaust is coming from the crankcase oil, having formed or accumulated there. To evaluate this possibility, 1-nitropyrene exhaust emissions from a light-duty diesel vehicle were measured, along with the 1-nitropyrene content of its engine oil and of new oil. Results indicate that new oil did not contain 1-nitropyrene at the detection limit of 0.1 ppm. 1-nitropyrene did collect in oil to a concentration of 0.5 ppm at an oil usage and vehicle travel distance of 9000 km. Even though 1-nitropyrene was found in used diesel engine oil, this 1-nitropyrene does not appear to account for the 1-nitropyrene found in diesel exhaust emissions.

Direct-acting mutagenicity of diesel particulate extract is unchanged by addition of neat aromatic compounds to diesel fuel

While there appears to be no consistent evident to suggest that an increase in the aromatic content (compounds >C/sub 14/) of diesel fuel will have an adverse affect on the emission of mutagenic material the effect of adding a large amount of a single aromatic compound (less than or equal to C/sub 14/) is unknown. Compounds were selected for this study, in part, because they are among the major aromatic compounds present in diesel fuel and because they are at a concentration less than 1 percent. Fourteen aromatic compounds were used in this study. It was concluded that the addition of neat aromatic compounds containing less than fourteen carbon atoms, with a variety of structures, to diesel fuel did not significantly alter the direct-acting mutagenicity of extracts of particles or the emission rate. A mechanical factor, injectors, did affect the direct-acting mutagenicity of the samples. The sensitivity of direct-acting mutagenicity to specific injectors should be investigated.