Characterization of polar compounds such as polycyclic aromatic ketones in air pollution including wood smoke

Environment International, Vol. 11, pp. 197-203, 1985 Printed in the USA. All rights reserved.

0160-4120/85 $3.00 + .00 Copyright © 1985 Pergamon Press Ltd.

CHARACTERIZATION OF POLAR COMPOUNDS SUCH AS POLYCYCLIC AROMATIC KETONES IN AIR POLLUTION INCLUDING WOOD SMOKE Thomas Ramdahl Central Institute for Industrial Research, P.O. Box 350 Blindern, N-0314 Oslo 3, Norway (Received 16 November 1983; Accepted 4 January 1985) The moderately polar compounds from various combustion emissions including wood smoke have been isolated by high performance liquid chromatography on silica gel. The compounds were analyzed by gas chromatography mass spectrometry. The various polycyclic aromatic compound (PAC) classes were determined by their characteristic mass spectra. Special emphasis has been given to the polycyclic aromatic ketones (PAK), which often are as abundant in environmental samples as polycyclic aromatic hydrocarbons (PAH). A number of moderately polar PACs have been synthesized and tested for mutagenicity in the Ames Salmonella mutagenicity assay and some PAKs were shown to be mutagenic but weaker mutagens than the nitro-PAH.

Introduction

Biomass combustion, specially of wood, is becoming increasingly popular as an energy source because of rising oil prices (Cooper and Malek, 1982). Particles originating from biomass combustion emissions are major contributors to air pollution (Cooper, 1980; Budiansky, 1980; Hall and DeAngelis, 1980; Ramdahl et al., 1984) and the composition of organic compounds adsorbed to these particles is extremely complex. Polycyclic aromatic hydrocarbons (PAH) are formed by combustion of carbonaceous materials, and much attention has been focused on the large number of PAH in wood combustion discharges (Snowden, 1975; Lee et al., 1977; Alsberg and Stenberg, 1979; DeAngelis et al., 1980a; Ramdahl et al., 1982a; Rudling et al., 1982). Residential wood combustion has been estimated to be a major source of PAH in the United States (DeAngelis et ai., 1980b). Recent studies based on the Ames Salmonella mutagenesis assay have indicated that organic extracts of particles from wood combustion possess mutagenic activity even in the absence of mammalian enzymes, comparable to extracts of diesel particles (L6froth, 1978; Ramdahl et al., 1982a; Rudling et al., 1982). These f'mdings have stimulated a research effort to identify mutagens in the extracts of biomass combustion emissions. Because PAH require enzymatic activation to create mutagenicity, other more polar derivatives

of PAH could be partly responsible for this direct mutagenicity (L6froth, 1978; Ramdahl et al., 1982a). The characterization of these compounds in our laboratory has involved fractionation of the complex sample by normal phase high performance liquid chromatography (HPLC) (Schuetzlc et al., 1981; Ramdahl and Bechcr, 1982; Ramdahl et al., 1982b) and the use of capillary gas chromatography and gas chromatographymass spectrometry (GC-MS) for analysis of the individual fractions (Ramdahl and Becher, 1982; Ramdahi et al., 1982b; Ramdahl, 1983). In the GC-MS studies, both electron impact (EI) and electron capture negative ion chemical ionization (NICI) techniques have been used. The wood combustion emission extracts have also been fractionated for biological testing (Alfheim et al., 1984). The results showed biological activity in the moderately polar fraction, but the highest activity was associated with the most polar compounds. The PAH derivatives, polycyclic aromatic compounds (PAC), studied so far in the wood combustion emissions are the moderately polar compounds.

Experimental Sample collection and preparation, and chemicals The emissions from wood-burning equipment were sampled from the stack with a quartz glass probe. The 197

198

Thomas Ramdahl

particles in the flue gas were collected on a Gelman glass-fibre type A-E, held at 125 °C. The flue gas was cooled and the condensate was collected in several impingers cooled gradually from 0 to - 6 0 °C. The dried flue gas was finally passed through a 5 cm x 5 cm column containing Amberlite XAD-2 adsorbent. The sampling system is illustrated in Fig. 1. The filter and the XAD-2 which collected emissions from wood and straw burning were extracted with dichloromethane. The condensates were acidified to pH 2 and extracted with dichloromethane. Many of the polycyclic aromatic compounds described in this paper have been synthesized at Ris6 National Laboratory (Roskilde, Denmark).

ionization (EI/CI) source was used. For NICI (negative ionization chemical ionization), methane was used as the reagent gas, the ion source pressure was maintained at 0.25 Torr and source temperature was 250°C. Primary ionization of the CI reagent gas was accomplished using a 70-eV beam of electrons generated from a heated rhenium filament with an emission current of 0.25 mA. Electron multiplier voltage was 1700 V. The EI spectra were recorded under identical conditions without methane reagent gas present. Sample introduction was accomplished by means of a Finnigan 9610 gas chromatograph directly interfaced to the mass spectrometer by the fused silica capillary column. Typical GC conditions were as follows: GC carrier gas, helium; velocity, 40 cm/sec at 100 °C; injector temperature, 280°C; interface, 240°C; column, 30 m x 0.25 mm i.d. DB-5 (J&W Scientific Rancho Cordova, CA; USA), film thickness, 0.25/~m; column temperature, 100-325 °C at 5 °C/min; the initial temperature was held for 3 min. The masses from 40 to 390 were scanned every second and the ion data were acquired by using an INCOS 2100 data system.

High Pressure Liquid Chromatography (HPLC) fraction The Waters HPLC system used consited of two Model 6000 A pumps, a Model U6K injector, a Model 720 System Controller, a Model 440 Absorbance Detector operating at 254 nm. A 300 mm x 7.8 mm i.d. semipreparative #Porasil column (Waters Associates) was used. The solvent flow as 2 mL/min. The column was conditioned by flushing with methylene chlorice (MeCI2) for 5 min and with 5o70 MeCI2 in n-hexane for 15 min. The extract was quantitatively injected into the column (injection volume 100-200 #L) using 5o70 MeC12 in hexane as the mobile phase. After 10 min under isocratic conditions, a linear gradient was started with 5°70 MeCl2/min. The moderately polar fraction of the extract was sampled between 24 and 50 min after injection.

Results and Discussion

Mass spectrometric techniques The electron impact (EI) ionization technique is the most widely used GC-MS ionization technique. The electron impact mass spectra of PAC are simple, mainly consisting of an intense molecular ion on a few characteristic fragment ions depending upon the particular class of compounds (Schuetzle et al., 1981; Ramdahl and Becher, 1982). The most characteristic fragments of unalkylated common PAC are summarized as follows:

Gas Chromatography-Mass Spectrometry (GC-MS) system A Finnigan model 4021 quadrupole mass spectrometer equipped with a standard electron impact/chemical

a) Polycyclic aromatic ketones (PAK) give abundant M ÷ and (M-CO) ÷ ions.

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Polar compounds in combustion emissions

199

tion with high resolution capillary gas chromatography retention times compared with authentic standards. In addition to the EI technique, the use of negative ion chemical ionization (NICI) with methane as a reagent gas has proven sensitive and selective for electron capturing compounds (Hunt and Crow, 1978). The NICI technique in MS is similar to that of the ECD for GC: the compounds with high electronegativity capture thermal electrons and form negative ions which are detected in the mass spectrometer. NICI has been useful in the analysis of PAK, PAQ, nitro-PAH, and other PAC classes (Ramdahl et al., 1982b; Newton et al. 1982; Oehme et al., 1982; Ramdahl, 1983). Because the compounds are ionized by capturing electrons with low energy, only the molecular ion M- is observed for most compound classes, an exception being nitro-PAH, which shows some fragmentation (Ramdahl et ai., 1982b; Newton et al., 1982).

b) Polycyclic aromatic quinones (PAQ) give abundam M ÷, (M-CO) ÷ and (M-C202) ÷ ions. c) Cyano-PAH give abundant M ÷ and (M-HCN) ÷ ions. d) Nitro-PAH give abundant M ÷, (M-NO) ÷, (M-NO2) ÷, and (M-CO2N) ÷ ions. e) P A H carboxaldehydes give abundant M ÷, (M-H) ÷, (M-CO) ÷, and (M-HCO) ÷ ions. f) P A H dicarboxylic acid anhydrides give abundant M ÷, (M-COs) ÷, and (M-C203) ÷ ions. In addition to these fragments, several minor ions appear due to losses of hydrogen atoms from the different ions, and after the loss of the substitutent, the resulting hydrocarbon ion (X) loses acetylene to form the (X-C~H2) ÷ ion. As for PAH, the formation of doubly charged ions is a rule for PAC in general. The corresponding doubly charged ions for all the molecular and fragment ions described above are observed in the EI mass spectra of these compounds. The EI mass spectra of various structural isomers of PAC are almost identical and cannot be used for unambiguous identification; this is achieved only in cornbina-

Moderately polar compounds The total ion chromatogram (EI) for the moderately polar fraction of a wood combustion particulate extract is shown in Fig 2. The chromatogram shows a complex

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Fig. 2. Reconstructed ion chromatogram (El) of the moderately polar fraction of wood combustion emission.

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mixture of compounds consisting mainly of low molecular weight benzene derivatives such as benzaldehyde, benzonitrile, phenols, and methylated and methoxyluted analogs, being breakdown products of the lignin in the wood. Also present is a range of terpenoids. In addition to this, several different classes of PAC have been identified, including PAK, PAQ, cyano-PAH, and PAH-carboxaidehydes (Ramdahl and Becher, 1982). The cyano-PAH are formed by combustion of nitrogen-containing fuels. This was shown by Dubay and Hites (1978) by combustion of a mixture of xylene and pyridine. Cyano-PAH have also been identified as combustion products of straw (Ramdahl and Becher, 1982), silk and wool (Chaigneu and Le Moan, 1976; Le Moan and Chaigneu, 1979) and nitrogen-containing polymers (Politzki et al., 1984). The other oxygenated PAC, such as PAK, PAQ and PAH-carboxaidehydes, have been identified in a number of combustion samples from diesel engines (Schuetzle et al., 1981; Newton et al., 1982; Ramdahl, 1983), gasoline engines (Alsberg et al., 1985) and biomass combustion (Ramdahl and Becher, 1982; Hubble et al., 1982). The formation of these compounds seems only to be a function of combustion conditions. Wood and hydrocarbon fuels are different in nature, still they give rise to the same oxygenated PAC combustion products.

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Polycyclic aromatic ketones The PAK is of special interest since these compounds are emitted from combustion processes in similar quantities to the emission of PAH. There is a range of PAK present in the emission samples; the most probable structures are given in Fig. 3. The most abudant ketones in the emissions are 9H-fluoren-9-one (structure 1), 4H-cyclopenta(def)phenanthren-4-one (structure 3), 7H-benz(de)anthracen-7-one (structure 8), and 6Hbenzo(cd)pyren-6-one (structure 12). We have determined the emissions of compounds 1 and 3 from wood combustion to be 6400 and 3500 #g/kg dry wood, respectively (Ramdahl and Becher, 1982). The emission of the PAK with molecular weights from 230 to 304 varied from 50 to 600/~g/kg, but the PAK of the phenalenone group (e.g., compounds 8 and 12) seem not to be quantitatively eluted from the HPLC in this study, due to insufficient HPLC elution time for the fraction. The emissions of some abundant PAH such as phenanthrene, pyrene, benz(a)anthracene, and benz(a)pyrene were 5800, 2700, 480, and 560 #g/kg dry wood, respectively. K6nig et al. (1983) have also demonstrated comparable amounts of compounds 8 and 12 to benz(a)anthracene and benzo(a)pyrene in ambient air. It is therefore important to assess their environmental significance. There are two different groups of PAK: those con-

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Fig. 3. Molecularstructuresof polycyclicaromaticketones.The molecularweightsare as follows:structures 1 and 2 (MW 180), structure3 (MW 204), structures4-8 (MW230), structures9-12 (MW254), structures, 13-15 (MW278), structures16-38(MW280), structure39 (MW302), structures 40-58 (MW 304), structure59 (exampleof MW 328) and structure60 (exampleof MW 330). The IUPAC namesof these structures have been reported (Ramdahl, 1983).

Polar compoundsin combustionemissions

201 From the standards available it is demonstrated that the PAK belonging to the phenalenone group have longer GC retention time on a nonpolar stationary phase than do the PAK in the fluorenone group. 1H-Phenalen-l-one (structure 2 in Fig. 3), 7H-benz(de)anthracen-7-one (structure 8), and 6H-benzo(cd)pyren6-one (structure 12) are eluted last of the PAK with MW 180, 230, and 254, respectively, whereas 13H-dihenz(bc,j)aceanthrylen-13-one (structure 50) elutes in the beginning of the PAK with MW 304. The two PAK groups are also separated by normal phase silica HPLC. The phenalenone group is eluted after the fluorenone group, as may also be seen in the data reported by Schuetzle et al. (1981). For PAK compounds with molecular weight 230 and higher those with the phenalenone group are most abundant in the environment. PAK may be formed by oxidation of P A H which contain a single-bonded carbon atom attached to the aromatic ring. The hydrogen atoms in the methylene group of fluorene show considerable reactivity, and fluorene and benzofluorenes are known to undergo rapid nonphotochemical oxidation to their respective ketones (Korfmacher et al., 1980). 1H-Phenalene, 7H-benz(de)anthracene, and 6H-benzo(cd)pyrene are known to be

taining a phenalenone substructure and those containing a fluorenone substructure, with the keto group situated in a six-membered and a five-membered ring, respectively. Only a few PAK have been positively identified by comparison with authentic standards, mostly compounds up to 254 in molecular weight (Ramdahl, 1983). Possible isomers of benz(de)anthracenones other than those given (compounds 7 and 8 in Fig. 3) (i.e., 3H-benz(de)anthracen-3-one, 4H-benz(de)anthracen-4one, and 6H-benz(de)anthracen-6-one) have not been included, because their corresponding parent hydrocarbons isomerize extremely rapidly to 7H-benz(de)anthracene (Danneberg and Kessler, 1959), corresponding to compound 8. The possible formation of these isomers should therefore be minimal. This fact is considered when giving the high molecular weight structures in Fig. 3; only benzologs of 7H-benz(de)-anthracen-7-one (compound 8) are given. There is good agreement between the theoretical number (cf. Fig. 3) of isomers of PAK and the occurrence of P A H isomers in environmental samples. Only one isomer each with molecular weight (MW) 204 and 302 are found, two isomers with MW 180, few isomers with MW 230, 254, and 278 and many isomers with MW 280, 304, 328 and 330 (see Fig. 4 for some examples).

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acidic and reactive hydrocarbons (Steitwieser et al., 1981), and are easily oxidized. Many PAH with the methylene group in a fivemembered ring are found in environmental samples. Grimmer et al. (1977) identified, among others, 11H-indeno(2,1,7-cde)pyrene, 4H-benzo(def)cyclopenta(mno)chrysene, and l lH-benzo(ghi)cyclopenta(pqr)perylene in automobile exhaust, representing high molecular weight reactive methylene hydrocarbons as precursors to PAI( compounds 13, 14, and 39, respectively. PAH with the methylene group in a sixmembered ring have not been reported in environmental samples, indicating their rapid oxidation. The occurrence of PAK in emission samples may be explained in two ways: (a) methylene PAH formed in the combustion process are so reactive that they are oxidized immediately after leaving the combustion zone, and PAK are actually emitted; or b) methylene PAH trapped in the sampling system are oxidized by the stack gas passing by.

Short-term bioassay and moderately polar PAC Several moderately polar PAC have been shown to be mutagenic in the Ames Salmonella assay (Ames et al., 1975). The nitro-PAH are the best studied PAC class, since some of these compounds are mutagenic (Rosenkranz et al., 1980; Mermelstein et al., 1981; Greibrokk et aL, 1985). 5-Cyanoacenaphthylene induced a significant mutation to 8-azaquanine resistance in Salmonella typhimurium (Krishnan et al., 1979). 9,10-Phenanthrene quinone and 9-hydroxyphenanthrene are weak mutagens in the Ames test (Brown and Brown, 1976), 9,10-anthracene quinone is toxic, and benzo(a)pyrene quinones are nonmutagenic (Brown and Brown, 1976; Pitts, 1979). Benzo(a)pyren-6-carboxaldehyde has been shown to induce high levels of tumor activity in mice (Dipple, 1976). In the Nordic project "Carcinogenic and mutagenic compounds from energy generation," several other PAC have been synthesized and tested for mutagenicity in the Ames test. The results for some of the compounds are given in Table 1. Except for the nitro compounds, none of the PAC tested showed high mutagenicity. Still, 1-cyanopyrene, 1-cyanoacenaphthylene, pyren-l-carboxaldehyde, 7H-benz(de)anthracen-7-one, benzo(b)fluorenone, and benzo(c)fluorenone were markedly mutagenic. Several of the other compounds showed no mutagenicity. Work is under way to synthesize more PAC for mutagenicity testing. Acknowledgements--A. Jebens and (3. Strand are thanked for assistance with source sampling and I. Hagen for evaluation of the mutagenicity testing. Financial support from the Nordic Council of Ministers is gratefully acknowledged. This study is part of an internordic study on "Carcinogenic and Mutagenic Compounds from Energy Generation" (MIL-2).

Thomas Ramdahl Table 1. Specific mutagenicity of polycyelic aromatic compounds tested in Ames Salmonella/microsome assay (rev/t~g). Tester Strain

Compound 1-Hydroxy-x-nitropyrene 5-Nitroacenaphthene l-Cyanopyrene

1-Cyanoacenaphthylene Pyrene- 1-carboxaldehyde 7H-Benz(de)anthraeen-7-one Benzo(c)fluorenone Benzo(b)fluorenone 9H-Anthrone 9,10-Dinitroanthracene 6H-Benzo(cd)pyren-6-one Pyren- 1-sulfonic acid Anthraceneepoxide Biphenyl-3-carboxyaldehyde Benzo(a)fluorenone 2-Cyanoacenaphthene Anthracen-9-carboxaldehyde 9-Nitroanthrone Retene Benzo(a)pyrene

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460 110 <1 + + + + 0.1 < 0.2 n.t. n.t. n.t. + + + + <1 + + +

aTA98/1.8DNP~. b+ = negative up to 100-500/~g/plate. cn.t. = not tested.

References Alfheim, I., Becher, G., Hongslo, J., and Ramdahl, T. (1984) Mutagenicity testing of high performance liquid chromatography fractions from wood stove emission samples using a modified Salmonella assay required smaller sample volumes, Environ. Mutag. 6, 91-102. Alsberg, T., Stenberg, U., Westerholm, R., Standell, M., Rannug, U., Sundvall, A., Romert, L., Bernson, V., Petterson, B., Toftg/u'd, R., Franz~n, B., Jansson, M., Gustafsson, J. /k., Egeback, K. E. and Tejle, G. Chemical and biological characterization of organic material from gasoline exhaust particles, Environ. Sci. TechnoL 19, 43-50. Alsberg, T. and Stenberg, U. (1979) Capillary GC-MS analysis of PAH emissions from combustion of peat and wood in a hot water boiler, Chemosphere 7, 487--496. Ames, B. N., McCann, J., and Yamasaki, E. (1975) Methods for detecting carcinogens and mutagens with the Salmonella/mammalian-microsome mutagenicity test, Mutat. Res. 31, 347-364. Brown, J. P. and Brown, R. J. (1976) Mutagenesis by 9,10-anthracene quinone derivatives and related compounds in Salmonella typhimurium, Mutat. Res. 40, 203-224. Budiansky, S. (1980) Bioenergy: The lesson of wood burning?, Environ. Sci. TechnoL 14, 769-771. Chaigneu, M. and G. Le Moan (1976) Analyse et ~volution des compos~s foum~s par pyrolyse et combustion de ia laine, Analusis 4, 28-33. Cooper, J. A. (1980) Environmental impacts of residential wood combustion emissions and its implications, J. Air Pollut. Control Assoc. 30, 855-861. Cooper, J. A. and Malek, D. eds. (1982) Residential Solid Fuels. Oregon Graduate Center, Beaverton, OR. Dannebcrg, H. and Kessler, H. J. (1959) Synthesis of steranthrenes. X. Isomeric benzanthrenes, Liebigs Ann. 620, 32--46. DeAngelis, D. G., Ruffin, D. S., and Reznik, R. B. (1980a) Preliminary characterization of emissions from wood fired residential combustion equipment. EPA-600/7-80-040, U.S. Environmental Protection Agency, Washington, DC.

Polar compounds in combustion emissions DeAngelis, D. G., Ruffin, D. S., Peters, J. A., and Reznik, R. B. (1980b) Source assessment: Residential combustion of wood. EPA~600/2-80-042b, U.S. Environmental Protection Agency, Washington, DC. Dipple, A. (1976) Polynuclear aromatic carcinogens, in Chemical carcinogens, C. E. Scarle, ed., p. 263. ACS Monograph 173, American Chemical Society, Washington, DC. Dubay, G. R. and Hites, R. A. (1978) Cyano-arenes produced by combustion of nitrogen-containing fuels, Environ. Sci. Technol. 12, 965-968. Greibrokk, T., L6froth, G., Nilsson,L., Toftg~rd, R., Carlstedt-Duke,J. and Gustafsson, J. A. (1985) Nitroarenes: Mutagenicity in the Ames Salmonella/microsome assay and affinity to the TCDDreseptor protein, in Toxicity of Nitroaromatic Compounds, D. E. Rickert, ed. pp. 167-183. Hemisphere Publ. Corp., Washington, DC. Grimmer, G., B6hnke, J., and Glaser, A. (1977) Polycyclische aromatische Kohlenwasserstoffe im Abgas yon Kraftfahrzengen, Erd61Kohle, Erdgas, Petrochemie, 30, 411-417. Hall, R. E. and DeAngelis, D. G. (1980) EPA's research program for controlling residential wood combustion emissions, J. Air Pollut. Control Assoc. 30, 862-867. Hubble, B. R., Stetter, J. R., Gebert, E., Harkness, J. B. L., and Flotard, R. D. (1982) Experimental measurements of emissions from residential wood-burning stoves in Residential Solid Fuels, J. A. Cooper, and D. Malek, eds., pp. 79-138. Oregon Graduate Center, Beaverton, OR, Hunt, D. F. and Crow, F. W (1978) Electron capture negative ion chemical ionization mass spectrometry, Anal. Chem. $0, 1781-1784. K6nig, J., Balfanz, E., Funke, W., and Romanowski, T. (1983) Determination of oxygenated polycyclicaromatic hydrocarbons in airborne particulate matter by capillary gas chromatography and gas chromatography/mass spectrometry, Anal. Chem. $$, 599-603. Korfmacher, W. A., Natusch, D. F. S., Taylor, D. R., Mamantov, G., and Wehry, E. L. 0980) Oxidative transformation of polycyclic aromatic hydrocarbons adsorbed on coal fly ash, Science 207, 763-765. Krishnan, S., Kaden, D. A., Thilly, W. G., and Hites, R. A. (1979) Cyanoarenes in soot: Synthesis and mutagenicity of cyanoacenaphthylenes, Environ. Sci. Technoi. 13, 1532-1534. Lee, M. L., Prado, G. P., Howard, J. B., and Hites, R. A. (1977) Source identification of urban airborne polycyclic hydrocarbons by gas chromatographic mass spectrometry and high resolution mass spectrometry, Biomed. Mass Spectrom. 4, 182-186. Le Moan, G. and Chalgnen, M. (1979) Analyse et ~volution des compos~s foum~s par pyrolys¢ et combustion de la soie, Analusis 7, 154-157. L6froth, G. (1978) Mutagenicity assay of combustion emissions, Chemosphere 7, 791-798. Mermelstein, R., Kirlazides, D. K., Buffer, M., McCoy, E. C., and Rosenkranz, H. S. (198 I) The extraordinary mutagenicity of nitro-

203 pyrenes in bacteria, Mutat. Rea. 89, 187-196. Newton, D. L., Erickson, M. D., Tomer, K. B., Pellizzari, E. D., Gentry, P., and Zweidinger, R. B. 0982) Identification of nitroaromatics in diesel exhaust particulate using gas chromatography/ negative ion chemical ionization mass spectroscopy and other techniques, Environ. Sci. Technol. 16, 206-213. Oehme, M., Man6, S., and Stray, H. (1982) Determination of nitrated polycyclic hydrocarbons in aerosols using capillary gas chromatography ~ombined with different electron capture detection methods, J. High Resol. Chromatogr. Chromatogr. Commun. 5, 417-423. Pitts, J. N., Jr. (1979) Photochemical and biological implications of the atmospheric reactions of amines and benzo(a)pyrene, Phil. Trans. R. Soc. Lond. A, 290, 551-576. Politzki, G., Lahaniatis, E. S., and Bieniek, D. (1984) Formation of cyanoarenes by combustion of nitrogen containing polymers, Chemosphere 13, 191-201. Ramdahl, T. (1983) Polycyclic aromatic ketones in environmental samples, Environ. Scl. Technol. 17, 666-670. Ramdahl, T. and Becher, G. (1982) Characterization of polynuclear aromatic hydrocarbon derivatives in emissions from wood and ceral straw combustion, Anal. Chim. Acta 144, 83-91. Ramdahl, T., Alfheim, I., Rustad, S., and Olsen, T. (1982a) Chemical and biological characterization of emissions from small residential stoves burning wood and charcoal, Chemosphere 11, 601-611. Ramdahl, T., Becher, G., and Bj~rseth, A. (1982b) Nitrated polycyclic aromatic hydrocarbons in urban air particles, Environ. Sci. Technol. 16, 861-865. Ramdahl, T., Schjoldager, J., Currie, L. A., Hanssen, J. E., M#IcT, M., Klouda, G. A., and Alfheim, I. (1984) Ambient impact of residential wood combustion in Elverum, Norway, Sci. Total Environ. 36, 81-90. Rosenkranz, H. S., McCoy, E. C., Sanders, D. R., Butler, M., Kiriazides, D. K., and Mermelstein, R. (1980) Nitropyrenes: Isolation, identification and reduction of mutagenic impurities in carbon black and toners, Science 209, 1039-1043. Rudling, L., Ahling, B., and L6froth, G. (1982) Chemical and biological characterization of emissions from combustion of wood and wood-chips in small furnaces and stoves, in Residential Solid Fuels, J. A. Cooper, and D. Malek, eds., pp. 34-53. Oregon Graduate Center, Beaverton, OR. Schuetzle, D., Lee, F. S.-C., Prater, T. J. and Tejada, S. (1981) The idenitification of polynuclear aromatic hydrocarbon derivatives in mutagenic fractions of diesel particulate extracts, Int. J. Environ. Anal. Chem. 9, 93-144. Snowden, W. D. (1975) Source sampling residential fireplaces for emission factor development. EPA-450/3-76-010, U.S. Envi~ronmentalProtection Agency, Rc~atch Triangle Park, NC. Streitwieser, A., Jr., Word, J. M., Gnib~, F., and Wright, J.S. (1981) Carbon activity. 62. Equilibrium acidities of some phenalene hydrocarbons: SCF-x MO correlations, J. Org. Chem. 46, 2588-2589.