Chemical Analysis of Diesel Particulate Matter and an Evaluation of Artifact Formation

Abstract

Methods for the sampling and analysis of diesel particulates have been evaluated. A number of different solvents were utilized for the extraction of diesel particulates. Benzo(a)pyrene (BaP) standards spiked on glass-fiber or quartz-fiber filters were found to be oxidized during the sampling of ambient air or exhaust gases. Such degradation was largely reduced by using filters with more inert surfaces, such as Teflon membranes. The results suggest that sample degradation due to gas-BaP reactions requires the presence of a reactive or catalytic medium, such as the glass-fiber filter surface. Such reactions can be minimized with the proper choice of a more inert filter surface such as Teflon. Oxidation of BaP was also observed in diesel extracts during analytical procedures or prolonged storage for several weeks in the dark. The implication of the sampling and analytical artifact problem is a question not only of analytical recovery but also of whether significant biologically active conversion products are produced. Analytical methods to study the extraction efficiency for BaP from diesel particulates are presented. High-performance liquid chromatography (HPLC), high-resolution mass spectrometry (HRMS), and gas chromatography-mass spectrometry (GC-MS) are being investigated for the identification and analysis of these species and preliminary results indicate the presence of a number of oxygenated polynuclear aromatic hydrocarbon (PAH) compounds, which potentially could be produced by oxidation during sampling and analysis.

Sampling of vehicle emissions for chemical analysis and biological testing.

“…The major techniques employed for the analysis of organic constituents in diesel exhaust include HPLC (19,37), TLC (13), MS/MS (18), and GC/MS (8,11,12,17,18,35,39). Computer controlled GC/MS (GC/MS/COM) is the most selective and sensitive analytical technique available for these analyses (19).…”

Mutagenic 1‐nitropyrene in wastewater from oil‐water separating tanks of gasoline stations and in used crankcase oil

“…Mutagenic nitrosubstituted polycyclic aromatic hydrocarbons (nitro-PAHs) have recently been found in carbon black and toners, airborne particulates, and diesel exhaust particulates [Jager, 1978;Lee et al, 1980;Lofroth et al, 1980;Rosenkranz et al, 1980;Gibson et al, 1981;Morita and Fukamachi, 1981;Pederson and Siak, 1981;Schuetzle et al, 1981;Tokiwa et al, 1981;Salmeen et al, 19821. These nitro-PAHs are readily produced when PAHs are exposed to nitrogen dioxide (NO2) [Pitts et al, 1978;Tokiwa et al, 19811.…”

Sampling of Vehicle Emissions for Chemical Analysis and Biological Testing

“…Lee (11,64) showed that the oxidation of PAH is greatly enhanced by the direct deposition of the PAH on the quartz or glass fiber filters used in the experiments by Pitts and Lane, and that PAH deposited on Teflon filters or adsorbed in particulates are much more stable toward chemical conversion. These effects are demonstrated by the recovery of BaP during various conditions of ambient air sampling as shown in Figure 3.…”

“…In order to determine the reactivity of PAH in the presence of diesel exhaust, extensive recovery experiments have been undertaken on PAH compounds in this laboratory (11,64,65) and at Battelle-Columbus Research Laboratories (66). Figure 4 summarizes results from several of these studies using fluoranthene (F), chrysene (C), pyrene (P) and benzo(a)pyrene (B).…”

“…Pitts (9,10) and Lee (11) reported the facile oxidation of PAH during ambient air and exhaust sampling and analysis, respectively, and the identification of PAH reaction products. Lee (11) and Schuetzle (12) initially demonstrated the presence of nitro-PAH in diesel particulates. Lee (11) and Schuetzle (12) initially demonstrated the presence of nitro-PAH in diesel particulates.…”