Chemical characterization and bioactivity of polycyclic aromatic hydrocarbons from non-oxidative thermal treatment of pyrene-contaminated soil at 250-1,000 degrees C.

In this paper we report yields, identities, and mutagenicities of products from heating a polycyclic aromatic hydrocarbon (PAH)-contaminated, Superfund-related synthetic soil matrix without exogenous oxygen. We heated batch samples of soil pretreated with 5.08 wt% (by weight) pyrene in a tubular furnace under a constant flow of helium gas at 250, 500, 750, and 1,000 +/- 20 degrees C. Dichloromethane (DCM) extracts of cooled residues of heated soil and of volatiles condensed on a cold finger after 1 sec residence time at furnace temperature were assayed gravimetrically and analyzed for PAH by HPLC, HPLC coupled to mass spectrometry, and gas chromatography coupled to mass spectrometry. All four temperatures volatilized pyrene and generated other PAHs, including alkylated pyrenes. We detected bioactive PAHs in the product volatiles: cyclopenta[cd]pyrene (CPP) at 750 and 1,000 degrees C and benzo[a]pyrene (BaP) at 1,000 degrees C. We found a clean soil residue, i.e., no pyrene or other DCM extracts, only at 750 degrees C. Control experiments with uncontaminated soil, pyrene, and Ottawa sand plus 4.89 wt% pyrene revealed no CPP or BaP production from soil itself, but these experiments imply that pyrene interactions with soil, e.g., soil-bound silica, stimulate CPP and BaP production. We detected mutagenicity to human diploid lymphoblasts (in vitro) in volatiles from 1,000 degrees C heating of soil plus pyrene and sand plus pyrene, and in the residue from 500 degrees C heating of soil plus pyrene. Three plausible pathways for pyrene conversion to other PAHs are a) a reaction with light gas species, e.g., soil- or pyrene-derived acetylene; b) loss of C(2)-units followed by reaction with a PAH; and c) dimerization with further molecular weight growth via cyclodehydrogenation. This study shows that thermal treatment of PAH-polluted soil may generate toxic by-products that require further cleanup by oxidation or other measures.

Mutagenicity of C24H14 PAH in human cells expressing CYP1A1.

Relatively little is known about the mutagenicity of C24H14 PAH, a diverse group of five- and six-ring PAH, some of which are present at trace levels in the environment. To better understand the mutagenicity of this class of compounds, 11 C24H14 PAH, including benzo[a]perylene, benzo[b]perylene, dibenzo[a,e]fluoranthene, dibenzo[a,f]fluoranthene, dibenzo[j,l]fluoranthene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene, dibenzo[e,l]pyrene, naphtho[1,2-b]fluoranthene, naphtho[2,3-a]pyrene, and naphtho[2,3-e]pyrene, were tested in a mutagenicity assay based on human h1A1v2 cells. h1A1v2 cells are a line of human B-lymphoblastoid cells that have been engineered to express cytochrome P4501A1 (CYP1A1), an enzyme capable of metabolizing promutagenic PAH. Mutagenicity was measured at the thymidine kinase (tk) locus following a 72-h exposure period. Our results show that nine of the compounds were mutagenic. Benzo[a]perylene, dibenzo[a,e]fluoranthene, dibenzo[a,i]pyrene, and naphtho[2,3-a]pyrene were the most potent mutagens, having minimum mutagenic concentrations (MMC) (i.e., the dose at which the induced response was twice that of the negative controls) in the 1-5 ng/ml range. Benzo[b]perylene, dibenzo[a,h]pyrene, dibenzo[a,f]fluoranthene, and naphtho[2,3-e]pyrene were somewhat less potent mutagens, having MMC in the 10-30 ng/ml range. Dibenzo[e,l]pyrene, which had an MMC of 280 ng/ml, was the least potent mutagen. Dibenzo[j,l]fluoranthene and naphtho[1,2-b]fluoranthene were not mutagenic at the doses tested (1-3000 ng/ml). The most mutagenic compounds were also quite toxic. At the highest doses tested, benzo[a]perylene, dibenzo[a,e]fluoranthene, dibenzo[a,i]pyrene, dibenzo[a,h]pyrene, and dibenzo[a,f]fluoranthene induced > 60% killing, and naphtho[2,3-a]pyrene and naphtho[2,3-e]pyrene induced > 50% killing. Benzo[b]perylene, dibenzo[e,l]pyrene, dibenzo[j,l]fluoranthene, and naphtho[1,2-b]fluoranthene induced < 50% killing at the highest doses tested. Comparing these results to a previous study in which nine other C24H14 PAH were tested for mutagenicity in this same assay, it was found that dibenzo[a]pyrene isomers were generally more mutagenic than the other groups of C24H14 PAH tested. These observations are discussed with emphasis given to identifying C24H14 PAH that may be important environmental mutagens.

Mutagenicity of cyclopenta-fused polynuclear aromatic hydrocarbons and a non-polar fraction from a fuel combustion sample in a Salmonella forward mutation assay without exogenous metabolic activation.

A series of cyclopenta-fused polynuclear aromatic hydrocarbons (PAH) were tested for mutagenicity in a bacterial forward mutation assay based on resistance to 8-azaguanine (8-AG) in Salmonella typhimurium TM677 in the absence of Aroclor-induced rat liver postmitochondrial supernatant (PMS). All of the aceanthrylenes tested were mutagenic in the absence of PMS, whereas none of the acephenanthrylenes were active. The following mutagenic potency series expressed as the minimum detectable mutagen concentration (MDMC) in nmol/ml was obtained: aceanthrylene (AA) (5.5); cyclopent[h,i]aceanthrylene (CPAA)(18.2); 6-methylaceanthrylene (6-MeAA)(112); 1,2,6,7-tetrahydrocyclopent[h,i]aceanthrylene (THCPAA) (166); 1,2-dihydroaceanthrylene (DHAA) (298). Saturation of the cyclopenta rings or methylation at the 6-position of AA reduced, but did not eliminate, mutagenicity measured in the absence of PMS. AA was unusual because it was approximately 4-fold more mutagenic in the absence of PMS than in its presence. The other aceanthrylenes tested were 1.3-10.7 times more mutagenic in the presence of PMS than in its absence to give an MDMC potency series of: CPAA (3.8); 6-MeAA (10.5); AA (19.9); THCPAA (52.9); DHAA (229). Approximately 20% of the PMS-independent mutagenicity in a combustion sample from ethylene burned under fuel-rich conditions was found in a fraction containing only non-polar, 4-7 ring PAHs, widely attributed to be mutagenic only in the presence of PMS. None of this mutagenicity could be attributed to aceanthrylenes, thus other non-polar PAHs appear to possess significant PMS-independent mutagenicity as well.

Mutagenicity of the atmospheric transformation products 2-nitrofluoranthene and 2-nitrodibenzopyranone in Salmonella and human cell forward mutation assays.

The mutagenicity of the atmospheric transformation products 2-nitrofluoranthene (2-NF) and 2-nitrodibenzopyranone (2-NDBP), as well as a related isomer 3-nitrodibenzopyranone (3-NDBP), was measured in quantitative forward mutation assays with bacteria (Salmonella typhimurium TM677) and in two metabolically competent human cell lines (MCL-5 and h1A1v2) that differ in their complement of cytochrome P450s and microsomal epoxide hydrolase. 2-NF was a potent mutagen in Salmonella TM677 both in the absence and presence of rat liver postmitochondrial supernatant (PMS). 2-NDBP was non-mutagenic in the absence of PMS, but was mutagenic in its presence. The converse result was obtained for 3-NDBP. The mutagenic potency series in Salmonella in the absence of PMS, expressed as the minimum detectable mutagen concentration (MDMC) in nmol/ml, was: 2-NF, 2.5; 3-NDBP, 16.9; and 2-NDBP, > 415. With PMS, the potency series was: 2-NF, 1.2; 2-NDBP, 15.1; 3-NDBP, 208. Neither 2-NDBP nor 3-NDBP were mutagenic at the tk locus in MCL-5 or h1A1v2 cells at up to 200 nmol/ml. 2-NF was also inactive in MCL-5 cells, but was a potent mutagen in h1A1v2 cells with an MDMC of 0.02 nmol/ml. Cytochrome P450 CYP1A1, present constitutively only in h1A1v2 cells, was implicated in 2-NF activation because mutagenicity was reduced by 55-80% when alpha-naphthoflavone (ANF) was present during incubation. The lack of mutagenicity in MCL-5 cells was attributed to the inability of 2-NF to induce CYP1A1 activity in this cell line. These data indicate a primary role for ring oxidation in 2-NF activation. Previous emphasis placed upon 2-NDBP as a major mutagen in ambient air may need to be modified in view of the negative results for this compound in the human cell assays and in the absence of PMS in Salmonella TM677. However, these findings support the concern that 2-NF may be a risk to human health.

Improved detection of polycyclic aromatic compounds in complex mixtures by liquid chromatographic fractionation on poly(divinylbenzene) prior to gas chromatography-mass spectrometry. Application to the analysis of diesel particulates.

Polycyclic aromatic compounds (PACs) are preferentially retained over other compound classes during high-performance liquid chromatography (HPLC) on poly(divinylbenzene) (PDVB) columns with a dichloromethane mobile phase. PAC retention during HPLC with PDVB/CH2Cl2 is governed by a multi-mode mechanism that has been previously described. This enhanced retention of PACs makes PDVB columns useful for isolating a PAC fraction from highly complex mixtures such as the emissions from fossil-fuels combustion. The cleaned-up PAC fraction yields a simple chromatogram with easily identified and quantified peaks without significant compound loss or danger of contamination. We illustrate the use of this clean-up method for the isolation of the PAC fraction from a standard reference diesel particulate sample.

Human cell mutagenicity of oxygenated, nitrated and unsubstituted polycyclic aromatic hydrocarbons associated with urban aerosols.

Polycyclic aromatic compounds (PAC) are ubiquitous pollutants in urban air that may pose risks to human health. In order to better assess the health risks associated with this class of compounds, a total of 67 PAC that either have been identified (55) or are suspected to be present (12) in urban aerosol samples were tested for mutagenicity in a forward mutation assay based on human B-lymphoblastoid cells. The cell line used (designated h1A1v2) constitutively expresses the cytochrome P4501A1, which is known to be necessary for the metabolism of many promutagens. The PAC tested included 39 polycyclic aromatic hydrocarbons (PAH). 19 oxygen-containing PAH (oxy-PAH) and nine NO2-substituted PAH (nitro-PAH). A total of 26 PAH were mutagenic. In comparing the minimum mutagenic concentrations of the mutagenic PAH with that of benzo[a]pyrene (B[a]P) it was found that dibenzo[a,l]pyrene (DB[al]P), cyclopenta[c,d]pyrene (CPP), naphtho[2,1-a]pyrene, dibenzo[a,e]pyrene (B[a]P) and 1-methylbenzo[a]pyrene were 24 +/- 21, 6.9 +/- 4.2, 3.2 + 3.0, 2.9 +/- 2.9 and 1.6+/- 1.4 times, respectively, more mutagenic than B[a]P, and that dibenzo[a,k]fluoranthene and B[a]P were approximately equally mutagenic. The 19 other mutagenic PAH were between approximately 2 and approximately 1800 times less mutagenic than B[a]P. Of the oxy-PAH tested only phenalenone, 7H-benz[d,e]anthracen-7-one, 3-nitro-6H-dibenzo[b,d]pyran-6-one, cyclopenta[c,d]pyren-3(4H)-one, 6H-benzo[c,d]pyren-6-one (BPK) and anthanthrenequinone were mutagenic; however, with the exception of BPK, these were over 50 times less active than B[a]P, BPK was approximately 3 times less active than B[a]P. Seven of the nitro-PAH were mutagenic including 9-nitroanthracene, 1-nitropyrene, 2-nitrofluoranthene, 3-nitrofluoranthene, 1,3-dinitropyrene, 1,6-dinitropyrene (1,6-DNP) and 1,8-dinitropyrene. 1,6-DNP was approximately 4 times less active than B[a]P; the six other mutagenic nitro-PAH were between 20 and 380 times less active than B[a]P. These results are discussed in terms of their relevance for determining the most important mutagens in ambient air. Based on reported concentrations of PAC in ambient aerosols, it is possible that CPP, DB[ae]P, DB[al]P and BPK could account for a greater proportion of the mutagenicity than B[a]P in some aerosols.

Seasonal and spatial variation of the bacterial mutagenicity of fine organic aerosol in southern california.

The bacterial mutagenicity of a set of 1993 urban particulate air pollution samples is examined using the Salmonella typhimurium TM677 forward mutation assay. Amibent fine particulate samples were collected for 24 hr every sixth day throughout 1993 at four urban sites, including Long Beach, central Los Angeles, Azusa, and Rubidoux, California, and at an upwind background site on San Nicolas Island. Long Beach and central Los Angeles are congested urban areas where air quality is dominated by fresh emissions from air pollution sources; Azuasa and Rubidoux are located farther downwind and receive transported air pollutants plus increased quantities of the products of atmospheric chemical reactions. Fine aerosol samples from Long Beach and Los Angeles show a pronounced seasonal variation in bacterial mutagenicity per cubic meter of- ambient air, with maximum in the winter and a minimum in the summer. The down-wind smog receptor site at Rubidoux shows peak mutagenicity (with postmitochondrial supernatant but no peak without postmitochondrial supernatant) during the September-October periods when direct transport from upwind sources can be expected. At most sites the mutagenicity per microgram of organic carbon from the aerosol is not obviously higher during the summer photochemical smog period than during the colder months. Significant spatial variation in bacterial mutagenicity is observed: mutagenicity per cubic meter of ambient air, on average, is more than an order of magnitude lower at San Nicolas Island than within the urban area. The highest mutagenicity values per microgram of organics supplied to the assay are found at the most congested urban sites at central Los Angeles and Long Beach. The highest annual average values of mutagenicity per cubic meter of air sampled occur at central Los Angeles. These findings stress the importance of proximity to sources of direct emissions of bacterial mutagens and imply that if important mutagen-forming atmospheric reactions occur, they likely occur in the winter and spring seasons as well as the photochemically more active summer and early fall periods.

Characterization of flame-generated C10 to C 160 polycyclic aromatic hydrocarbons by atmospheric-pressure chemical ionization mass spectrometry with liquid introduction via heated nebulizer interface.

Complex mixtures of polycyclic aromatic hydrocarbons (PAHs) generated from fuel-rich combustion of ethylene-naphthalene mixtures in a jet-stirred-plug-flow reactor were chemically characterized by combined mass spectrometric techniques to yield product composition data that cover the molecular mass region from simple PAHs (naphthalene, 128 u) to large molecules comparable in molecular size (1792 u) to nanoparticles of soot. Two techniques based on atmospheric-pressure chemical ionization mass spectrometry (APCI-MS) were investigated: (1) APCI-MS combined with high-performance liquid chromatography through a heated nebulizer interface was found suitable for PAHs up to C36 (448 u). (2) For the characterization of larger PAHs beyond C36, direct liquid introduction (DLI) of sample into an atmospheric-pressure chemical ionization mass spectrometer through a heated nebulizer gave protonated molecular ions for PAHs over the m/z 400-2000 range. Although unequivocal elemental composition information is unattainable from the unit-resolution DLI/APCI-MS data, by starting with structural data from identified C16 to C32 PAHs, and applying PAH molecular growth principles, it was possible to generate PAH molecular maps from the DLI/APCI-MS data from which values for the elemental composition could be derived for all major peaks.

Bacterial mutagenicity of pyrolysis tars produced from chloro-organic fuels.

Droplets of toluene and three chlorinated organics, ortho-dichlorobenzene, 1,2-dichloroethane, and trichloroethylene, were pyrolyzed in pure nitrogen. The composition and bacterial mutagenicity of the product tars were measured. The presence of organic chlorine was found to affect both pyrolysis product tar composition and total tar mutagenicity. Pyrolysis in the absence of chlorine produced tars whose bacterial mutagenicity was found to be largely due to the presence of cyclopenta[cd]pyrene, fluoranthene, and benzo[a]pyrene. Small amounts of chlorine in the fuel (i.e., Cl/H molar ratios of less than 0.3) enhanced the formation of highly condensed polycyclic aromatic hydrocarbons (including cyclopenta[cd]pyrene) and increased tar mutagenicity. Larger amounts of organic chlorine (Cl/H ratios of between 0.3 and 0.6) resulted in significant yields of mono- and dichlorinated aromatics and higher levels of tar mutagenicity, which could not be accounted for by the presence of mutagens produced by pyrolysis in the absence of chlorine. Furthermore, unlike tars containing little or no chlorine, tars containing aryl chlorine were more mutagenic in the absence of added enzymes (intended to mimic in vivo mammalian metabolism) than in their presence. We hypothesize that at least one of the chlorinated aromatic products is strongly mutagenic. Two specific conditions that gave notably different results were a) the low-temperature (i.e., below 1400 K) pyrolysis of ortho-dichlorobenzene, which produced tri- and tetrachlorinated biphenyls almost exclusively; and b) the chlorine-rich pyrolysis of trichloroethylene, during which mostly perchloroaromatics were formed. Neither of these tars was found to mutate bacteria.

Bacterial and human cell mutagenicity study of some C18H10 cyclopenta-fused polycyclic aromatic hydrocarbons associated with fossil fuels combustion.

A number of isomeric C18H10 polycyclic aromatic hydrocarbons (PAHs), thought to be primarily cyclopenta-fused PAHs, are produced during the combustion and pyrolysis of fossil fuels. To determine the importance of their contributions to the total mutagenic activity of combustion and pyrolysis samples in which they are found, we characterized reference quantities of four C18H10 CP-PAHs: benzo[ghi]fluoranthene (BF), cyclopenta[cd]pyrene (CPP), cyclopent[hi]acephenanthrylene (CPAP), and cyclopent[hi]aceanthrylene (CPAA). Synthesis of CPAA and CPAP is described. The availability of reference samples of these isomers also proved to be an essential aid in the identification of the C18H10 species often found in combustion and pyrolysis samples. Chemical analysis of selected combustion and pyrolysis samples showed that CPP was generally the most abundant C18H10 isomer, followed by CPAP and BF. CPAA was detected only in pyrolysis products from pure PAHs. We tested the four C18H10 PAHs for mutagenicity in a forward mutation assay using S. typhimurium. CPP, BF, and CPAA were roughly twice as mutagenic as benzo[a]pyrene (BaP), whereas CPAP was only slightly active. These PAHs were also tested for mutagenic activity in human cells. In this assay, CPP and CPAA were strongly mutagenic but less active than BaP, whereas CPAP and BF were inactive at the dose levels tested. Also, the bacterial and human cell mutagenicity of CPAA and CPAP were compared with the mutagenicity of their monocyclopenta-fused analogs, aceanthrylene and acephenanthyrlene. Although the mutagenicities of CPAP and acephenanthrylene are similar, the mutagenic activity of CPAA is an order of magnitude greater than that of aceanthyrlene.

C60 and C70 fullerene isomers generated in flames. Detection and verification by liquid chromatography/mass spectrometry analyses.

Fullerenes C60 and C70, generated by combustion, have been shown previously to be produced in controlled laminar flames accompanied by other compounds having fullerene-like characteristics. Analysis of these additional compounds by high-performance liquid chromatography, coupled on-line with mass spectrometry has identified them as isomers of the C60 and C70 fullerenes. The newly observed isomers have characteristic UV spectra and are thermally unstable, undergoing conversion to the more stable fullerenes with a half-life of about 1 h in boiling toluene (111 degrees C). Isomers of C60 and C70 fullerenes previously have been studied theoretically, but not observed experimentally. The flame-generated material also contains C60O and C70O compounds, as well as C76 and higher carbon clusters.

Effect of column and mobile phase modifications on retention behavior in size exclusion chromatography of polycyclic aromatic hydrocarbons on poly(divinylbenzene).

Results are reported from a study, the goal of which was the reduction of the nonsize effects that govern the size exclusion chromatography (SEC) of planar polycyclic aromatic hydrocarbons (PAHs) on poly(divinylbenzene) (PDVB). Thought to arise from electron-pair donor--electron-pair acceptor (EPD-EPA) interactions between column packing and PAH eluate, nonsize effects could be substantially reduced by the addition of bulky substituents to the PAH, thereby perturbing EPD-EPA interactions between column and eluate. In this work we study the effect of adding a bulky substituent to the column material itself and have selected a sulfonated column material for this purpose. The-SO2OH group provides considerable steric shielding of the PDVB phenyl groups from the PAH eluates and thus its presence could weaken column-eluate interactions, but it is also electron-withdrawing and could possibly aggravate nonsize behavior, because the electron-pair acceptor strength of PDVB could be increased by electron-withdrawing substituents. It was found that either an increase or decrease of EPD-EPA bonding could result with the sulfonated PDVB (S-PDVB) columns, depending on the nature of the mobile phase. Size-dependent elution of PAHs could be obtained with S-PDVB for two classes of PAH by the inclusion of a small amount of hydrogen-bonding solvent, i.e. methanol, to the mobile phase. It is thought that the methanol additive, by strongly hydrogen bonding with the S-PDVB sulfonic acid groups, provides the additional steric shielding necessary to minimize EPD-EPA interactions.

Fullerenes C60 and C70 in flames.

The fullerenes C60 and C70 were first identified in carbon vapour produced by laser irradiation of graphite, and have recently been produced in macroscopic quantities by vaporization of graphite with resistive heating. It has also been suggested that fullerenes might be formed in sooting flames, and indeed all-carbon ions with mass/charge ratios suggestive of fullerenes have been detected in flames. These species were assumed to have the cage structures of fullerenes, but the mass spectroscopic evidence could not establish this conclusively. We have now collected samples of condensible compounds and soot from hydrocarbon combustion under a range of conditions, and analysed these using conventional techniques in an effort to detect fullerenes. Spectroscopic studies reveal the presence of C60 and C70 in yields and ratios that depend on temperature, pressure, carbon/oxygen ratio and residence time in the flame. Control of these conditions allows optimal yields of 3 g of fullerenes per kilogram of fuel carbon burned, and variation of the C70/C60 ratio over the range 0.26-5.7.

A high-yield sampler for toxicological characterization of complex mixtures in combustion effluents.

Combustion sampling for toxicological assessment often requires that large (greater than 100 mg) lots of complex organic mixtures of wide volatility range be rapidly recovered from high temperature gases without contamination. A new sampler, meeting these criteria for studies of public health interest, has been developed and demonstrated. The device provides high sampling rates and intimate contacting of the samples stream with large volumes of a well-cooled, liquid solvent, dichloromethane (DCM). This promotes rapid organics dissolution from carrier gas and particulates and prompt dilution and quenching of the resulting solution, resulting in high organics collection efficiencies with minimal DCM losses. Solvent separation then remits large quantities of concentrated organics for chemical analysis and toxicological testing. One- to seven-hour interrogations of in-flame, post-flame, and flue gas regions gave 50- to 250-mg yields of complex organic mixtures. In side-by-side sampling of combustion exhaust, the DCM sampler provided higher yields of DCM solubles (identified with complex organic mixtures) and of S. typhimuirim mutagens (active without exogenous metabolizing agents) than did a filter/polymeric sorbent bed sampling train. The new sampler also collects polar and high volatile hydrocarbons such as benzaheyde, pentadiyne, m- and p-diethynyl-benzene, and 1-hexen-3,5-diyne. Nitration of naphthalene and pyrene in DCM solution (1 mg/mL each) was less than 1 part in 10(7) after a 345-min exposure to a bubbling flow of moist N2/air mixture (1:1 v/v) containing 107 ppm NO and 1.5 ppm NO2, indicating that for these condition a DCM sampler should resist artifactual nitration of aromatics. However, because of the very high bacterial mutagenicity of some nitroaromatics and the wide range of sampling conditions of environmental interest, nitration and all artifacts must still be scrutinized when using the DCM sampler. The DCM sampler is expected to contribute to public health impact assessments by facilitating detailed determinations of the identities, compositions, concentrations, sources, formation mechanisms, and biological activity of environmental toxicants in gaseous atmospheres.

Evaluation of cyano bonded phases for the fractionation of bioactive complex mixtures.

Cyanopropyl bonded-phase sorbents are investigated for the liquid chromatographic (LC) fractionation of complex mixtures with the goal of extending routine sample fractionation to samples containing highly polar biologically active components. Separations based both on gravity-flow column chromatography and on high performance liquid chromatography (HPLC) are evaluated for efficiency and resolving power. Typical gravity-flow column separations of neutral to moderately polar mixtures are found to be less effective than those employing traditional sorbents; however, HPLC methods could be called upon to provide the resolving power necessary for satisfactory separations of these mixtures. For mixtures of polar reference compounds, cyano bonded phases provide good separations and are very efficient, permitting the elution of components too polar to be recovered from traditional sorbents. A scheme combining gravity-flow chromatography with HPLC is developed for the fractionation of complex mixtures into compound classes. It is based on the chromatographic behavior of reference compounds covering a wide polarity range utilizing cyanopropyl sorbents exclusively. Results are presented for the fractionation of two air particulate reference samples containing highly polar components.

Chemical and toxicological characterization of residential oil burner emissions: I. Yields and chemical characterization of extractables from combustion of No. 2 fuel oil at different Bacharach Smoke Numbers and firing cycles.

Particulates and complex organic mixtures were sampled from the exhaust of a flame retention head residential oil burner combusting No. 2 fuel oil at three firing conditions: continuous at Bacharach Smoke No. 1, and cyclic (5 min on, 10 min off) at Smoke Nos. 1 and 5. The complex mixtures were recovered by successive Soxhlet extraction of filtered particulates and XAD-2 sorbent resin with methylene chloride (DCM) and then methanol (MeOH). Bacterial mutagenicity [see Paper II (8)] was found in the DCM extractables. Samples of DCM extracts from the two cyclic firing conditions and of the raw fuel were separated by gravity column chromatography on alumina. The resulting fractions were further characterized by a range of instrumental methods. Average yields of both unextracted particulates and of DCM extractables, normalized to a basis of per unit weight of fuel fired, were lower for continuous firing than for cyclic firing. For cyclic firing, decreasing the smoke number lowered the particulates emissions but only slightly reduced the average yield of DCM extractables. These and similar observations, here reported for two other oil burners, show that adjusting the burner to a lower smoke number has little effect on, or may actually increase, emissions of organic extractables of potential public health interest. Modifications of the burner firing cycle aimed at approaching continuous operation offer promise for reducing the amount of complex organic emissions. Unburned fuel accounted for roughly half of the DCM extractables from cyclic firing of the flame retention head burner at high and low smoke number. Large (i.e., greater than 3 ring) polycyclic aromatic hydrocarbons (PAH) were not observed in the DCM extractables from cyclic firing. However, nitroaromatics, typified by alkylated nitronaphthalenes, alkyl-nitrobiphenyls, and alkyl-nitrophenanthrenes were found in a minor subfraction containing a significant portion of the total mutagenic activity of the cyclic low smoke samples (8). Oxygen-containing PAH, typified by phenalene-1-one and its alkyl derivatives, are important mutagens from cyclic firing at high smoke conditions. Thus, oil burner effluents differ markedly from those of several other combustors, including the automotive diesel engine, where multiring PAH, typified by fluoranthene and alkylated phenanthrenes, account for a significant portion of the effluent mutagenicity. Implications for combustion and emissions source identification are discussed.