Environ. Sci. Technol. 1982, 16, 861-865
(8) Kbrtum, G.; Braun, W. Ann. N.Y. Acad. Sei. 1960,632, 104-115. (9) Inscoe, M. N. Anal. Chem. 1964,36,2505-2506. (10) Fatiadi, A. J. Environ. Sci. Technol. 1967,1, 570-572. (11) Tebbens, B. D.;Thomas, J. F.; Mukai, M. Am. Ind. Hyg. ASSOC. J . 1966,27,415-422. (12) Thomas, J. F.; Mukai, M.; Tebbens, B. D. Environ. Sci. Technol. 1968,2,33-39. (13) Tebbens, B. D.; Mukai, M.; Thomas, J. F. Am. Znd. Hyg. ASSOC. J . 1971,32,365-372. (14) Korfmacher, W. A.; Wehry, E. L.; Mamantov, G.; Natusch, D. F. S. Environ. Sci. Technol. 1980,14,1094-1098. (15) Butler, J. D.; Crossley, P. Atmos. Environ. 1981,15,91-94. (16) Daisey, J. M. Ann. N.Y. Acad. Sei. 1980,338,50-69. (17) Saltzman, B. E.;Cook, W. A.; Dimitriades, B.; Ferrand, E. F.; Kothny, E. L.; Levin, L.; McDaniel, P. W.; Johnson, C. A. In "Methods of Air Sampling and Analysis", 2nd ed.; Katz, M., Ed.; American Public Health Association: Washington, DC, 1977;pp 556-559. (18) Leighton, P. A.; Lucy, F. A. J. Chem. Phys. 1934,2,756-759. (19) Pitts, J. N., Jr.; Cowell, G. W.; Burley, D. R. Environ. Sci. Technol. 1968,2,435-437. (20) Leighton, P. S."Photochemistry of Air Pollution"; Academic Press: New York, 1961. (21) New York State Dept. of Environmental Conservation, Division of Air, "New York State Air Quality Report DAR-80-1. Continuous and Manual Air Monitoring System", 1979 Annual Report. (22) Rothenberg, S.J. Atmos. Environ. 1980,14,445-456. (23) Katz, M.;Chan, C.; Tosine, H.; Sakuma, T. In "Carcinogenesis: A Comprehensive Survey. Polynuclear Aromatic Hydrocarbons. Third International Symposium"; Jones, P. W., Liber, P., Eds.; Ann Arbor Science: Ann Arbor, MI, 1979;pp 171-189. (24) Coughlin, R. W.;Ezra, F. S. Environ. Sci. Technol. 1968, 2,291-297.
veloped for laboratory studies of the degradation of absorbed PAH under simulated environmental conditions. The reactor is inexpensive, is simple to construct and operate, and is three dimensional, i.e., particles can be suspended in air or other gases during irradiation. In contrast to a flow-through system, the fluidized-bed photoreactor permits unlimited reaction time. It is possible to vary the photoreactor system over a wide range of conditions. Specifically, the adsorbed compound, gas composition, particle substrate, light intensity, humidity, and temperature may be varied, and a wide range of particles sizes can be used in the reactor. The reactor is suitable for studies of both the rates and products of degradation of PAH since relatively large samples are available for analyses. Most importantly, the rates of degradation determined in the photoreactor have been shown to be highly reproducible, generally to within f20% or less at the 95% confidence level.
Acknowledgments The suggestions and comments of T. J. Kneip, F. Mukai, R. Hershman, and P. Lewandowski are gratefully acknowledged. We also thank B. L. VanDuuren for providing laboratory facilities for M.Z. for some of the experiments reported here. Literature Cited National Academy of Sciences, Committee on Biological Effects of Atmospheric Air Pollutants, "Particulate Polycyclic Organic Matter Biologic Effects of Atmospheric Pollutants"; Dunham, C. L., Ed.; Washington, D.C., 1972. Lloyd, J. W. J . Occup. Med. 1971,13,53-68. Redmond, C. K.; Strobino, B. R.; Cypress, R. H. Ann. N.Y. Acad. Sei. 1976,271,102-115. Hammond, E. C.; Selikoff, I. J.; Lawther, P. L.; Seidman, H. Ann. N.Y. Acad. Sei. 1976,271,116-124. Cooper, J. A. J. Air Pollut. Control Assoc. 1980,30,855-861. Falk, H. L.;Markul, I.; Kotin, P. AMA Arch. Ind. Health 1956,13, 13-17. Voyatzakis, E.; Jannakoudakis, D.; Dorfmuller, T.; Sipitanos, C. C. R. Hebd. Seances Acad. Sci 1959, 249, 1756-1757.
Received for review February 5,1982.Accepted August 11,1982. This research was supported by Grant No. 5R23 ES01691 from the National Institute of Environmental Health Sciences and the US.Environmental Protection Agency and by a grant from the American Petroleum Institute and is part of a Center Program supported by the National Institute of Environmental Health Sciences, Grant No. ES00260, and the National Cancer Institute, Grant No. CA13343.
Nitrated Polycyclic Aromatlc Hydrocarbons in Urban Air Particles Thomas RamBahl," Georg Becher, and Alf BjOrsetht
Central Institute for Industrial Research, Blindern, Oslo 3, Norway
rn The organic extract of urban air particles from St. Louis,
MO,was fractionated by high-performance liquid chromatography. The moderately polar fraction was characterized by gas chromatography-electron impact and methane negative ion chemical ionization mass spectrometry. The compounds identified in the sample included nitronaphthalene, 9-nitroanthracene, 3-nitrofl~orantheae~ 1-nitropyrene, arenecarbonitriles, and several polycyclic ketones, quinones, and anhydrides. These studies represent the first mass spectrometric evidence of nitroaromatics in urban air particles. Several studies have shown that organic extracts of urban air particles exhibit mutagenic activity in the Ames Salmonella test (1-5). Until recently this activity was Present address: DEMINEX (Norge) A/S, Vika, Oslo 1, Norway. 0013-936X/82/0916-0861$01.25/0
mainly attributed to the polycyclic aromatic hydrocarbons (PAH),particularly benzo[a]pyrene (BaP)(6,7).However, the BaP content can only account for a minor part of the mutagenicity (8). Unlike PAH, extracts of air particles are often mutagenic also in the absence of a mammalian metabolic activation system. Apart from extracts of urban air, this type of mutagens has been detected in the exhaust of gasoline (9) and diesel engines (IO), in emissions from hot-water boilers fired with oil, peat, and wood chips (11)) and in fly ash from coal-fired power plants (12,13).It has been suggested that some of these mutagenic compounds are nitroaromatics (9,II). Using nitro-reductance-deficient strains in the Ames test, Wang et al. (14) have recently presented indirect evidence that the mutagenic activity of air particles may come from such compounds. Jager (15) has by means of thin-layer chromatography (TLC) and fluorescence quenching demonstrated the presence of 3nitrofluoranthene and 6-nitrobenzo[a]pyrene in the air of Prague.
0 1982 American Chemical Society
Envlron. Scl. Technol., Vol. 16, No. 12, 1982 861
The nitroaromatics are moderately polar compounds and can, together with oxygenated compounds of similar polarity, be separated from other compounds in a complex mixture by normal-phase high-performance liquid chromatography (HPLC) on silica (16,17). Methane (electron capture) negative ion chemical ionization mass spectrometry (NICIMS) (18) has been shown to be a very sensitive and selective analytical method for electron-capturing compounds such as nitroaromatics (18, 19). The detection limit (signal to noise ratio 1O:l) was 1 pg for a methylnitronaphthalene tested (19). As the levels of nitroarenes and other moderately polar compounds are very low in air particles, the NICIMS technique seems to be the method of choice for characterizing such samples, in addition to the more common electron impact mass spectrometry. The aim of this study was to fractionate an extract of air particles from St. Louis, MO, and to characterize the moderately polar fraction by fused silica capillary gas chromatography-mass spectrometry (GCMS), utilizing both electron impact and methane negative ion chemical ionization. Experimental Section Particle Collection and Sample Preparation. The sample consisted of urban air particles collected in St. Louis, MO, by using large fiber bag houses especially designed for this purpose. The collection of samples took place over a period of 18 months and is a time-integrated sample. The sample is similar (but not necessary identical) to the urban air inorganic standard reference material (SRM 1648) provided by National Bureau of Standards, Washington DC (20). A 1-g sample of the particles was Soxhlet extracted for 16 h with 50 mL of toluene. The extract was carefully concentrated to near dryness on a rotary evaporator, redissolved in methylene chloride, and filtered through a 0.45-pm PTFE membrane filter. HPLC Fractionation. The extract was fractionated into a nonpolar fraction and a neutral, moderately polar fraction by using normal-phase HPLC. A Waters HPLC system was used consisting of two Model 6000 A pumps, a Model U6K injector, a Model 720 system controller, a Model 440 absorbance detector operating a t 254 nm, and a Kontron Model SFM 23LC spectrofluorometer operating at bX305 nm and A, 430 nm. The column used was a 300 mm X 7.8 mm i.d. semipreparative pPorasil column (Waters, Assoc.). The solvent flow was 2 mL/min. Several 2-mL volumes of acetonitrile were injected to establish a proper blank. The column was conditioned by flushing with methylene chloride (CH2C12)for 5 min and with 5% CH2C12in hexane for 15 min. The extract was quantitatively injected into the column (injection volume 100-200 pL) by using 5% CHzClzin hexane as mobile phase. After 10 min under isocratic conditions a linear gradient was started with 5% CH2C12/min. The moderately polar fraction of the extract was sampled between 24 and 39 rnin after injection including compounds with k between 3.1 and 5.7. GCMS System. All spectra were recorded on a Finnigan Model 4021 quadrupole mass spectrometer equipped with a standard electron impact/chemical ionization (EI/CI) source. Primary ionization of the CI reagent gas was accomplished by using a 70-eV beam of electrons generated from a heated rhenium filament with an emission current of 0.25 mA. Methane was used as reagent gas, the ion source pressure was maintained at 0.15 torr, and source temperature was 250 "C. Electron multiplier voltage was 1700 V. The E1 spectra were recorded under 882 Environ. Sci. Technoi., Vol. 16, No. 12, 1982
Table I. Capacity Factors of Some PAH and PAH Derivatives Using Normal-Phase Chromatography on a 300 mm X 7.8 mm i.d. Semipreparative pPorasil Column compound pyrene coronene 2-methyl-1-nitronaph thalene 1-nitropyrene pyrene-1-carbonitrile anthraquinone 9-fluorenone
capacity factor k' 0.91 2.69 3.34 3.93 4.31 4.82 4.84
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: injector temperature, 280 "C; interface, 240 "C; GC carrier gas, helium; flow rate, 40 cm/s at 100 "C. Recording of E1 spectra: 30 m X 0.20 mm i.d. CP Si1 5 (Chrompack); film thickness, 0.20 pm; column temperature, 100-300 "C at 4 "C/min, with the initial temperature held for 5 min. Recording of negative ion chemical ionization (NICI) spectra: 30 m X 0.25 mm i.d. DB-5 (J. & W. Scientific, Inc.), film thickness 0.25 pm; column temperatures, 100-325 "C at 5 "C/min, with the initial temperature held for 3 min. The masses from 40 to 390 amu were scanned every 1 s. The ion data were acquired by using an INCOS 2100 data system. Chemicals. All solvents were HPLC grade from Rathburne Chemicals Ltd., Scotland. Standard compounds of PAH and PAH derivatives were obtained from different commercial sources. Pyrene-1-carbonitrile was a gift from A. Berg, University of Aarhus, Denmark. Results and Discussion Fractionation. The composition of organic extracts from air particulate matter is extremely complex, consisting of aliphatic hydrocarbons, PAH and N- and Sheterocyclics, oxygenated organics, and a variety of other organic compounds (21). Thus, chemical analyses of classes of compounds or individual species often require prefractionation. The most widely used fractionation schemes include solvent/solvent extraction for separation into weak and strong acid, basic, and neutral portions. The neutral fraction is commonly fractionated further according to functionalities by using open column chromatography. The main disadvantages of these techniques are the large sample size required for fractionation, slow speed, and the lack of reproducibility. Normal-phase HPLC has recently shown increasing use in the direct fractionation of environmental samples (16, 17). Table I shows the capacity factors (12') of some PAH and PAH derivatives on a semipreparative silica gel column. Compounds of different chemical types are easily separated under these conditions as shown by the selectivity between pyrene and 1-nitropyrene (a = 4.32) and 1nitropyrene and pyrene-1-carbonitrile (a = 1.10). Methane Negative Ion Chemical Ionization Mass Spectrometry vs. Electron Impact Mass Spectrometry. Two different ionization techniques were utilized in the GCMS studies. The electron impact (EI) ionization method is well-known, and many thousand reference spectra are available. NICI is a more recent technique (18, 22, 23). When methane is used as the reagent gas, no reagent negative ions are formed (18). Methane acts as
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Flgure 1. Reconstructed ion chromatogram (EI) of the moderately polar fraction.
Flgure 2. Mass spectrum (EI) of scan 1138. 10'
Table 11. Compounds Characterized b y GCMS with E1 Technique
253 406 463 634 670 997 1138
M, 148 162 162 176 173 180 198
1359 1470 1564 1896 2136 2190
208 204 222 230 247 258
scan
0
compound phthalic anhydride methylphthalic anhydride methylphthalic anhydride dimethylphthalic anhydride nitronaphthalene fluorenone naph thalenedicarboxylic anhydride anthraquinone cyclopenta[ d e f phenanthrone methylanthraquinone benzanthrone nitro( pyrene/fluoranthene) benz[ alanthraquinone
a moderator, and a large population of thermal electrons is produced, which can be captured by high electron affinity molecules by resonance capture. Little fragmentation is expected by this mechanism as the captured electrons have low energy, and hence the ECNICI spectra most often do not give the structural information as do the E1 spectra. Nitro-PAH, however, show some characteriatic fragmentation by the ECNICI technique, and this can be used to distinguish them from other compounds in the moderately polar fraction (29). GCMS with E1 Technique. The reconstructed ion chromatogram of the moderately polar fraction is shown in Figure 1. The chromatogram was very complex with a large envelope toward the end. This envelope consisted mainly of long-chain aliphatic aldehydes and/or ketones. The E1 spectra of these compounds showed very weak molecular ions with molecular weights up to 418, and a common fragment series of the m/z 43,57,71,82,96, and 110 ions. The polycyclic organic compounds characterized in this fraction are given in Table 11. We had little access to reference compounds in this study, and hence the characterization of compounds is based mainly on the mass spectra. When no definitive identity of a compound is given, it means it could be one of several isomers of the compound. Most of the compounds are oxygenated compounds which show very characteristic fragmentation. The phthalic anhydrides and naphthalenedicarboxylic anhydride show the fragments (M - 44)+ and (M - 72)+,which are due to loss of C02 and Cz03,respectively. The E1 mass spectrum of naphthalene dicarboxylic acid anhydride is shown in Figure 2. The ketones show the (M - 28)+
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fragment ion, and the quinones show the (M - 28)' and (M - 28 - 28)' fragment ions. The E1 mass spectra of compounds assigned as 4H-cyclopenta [ def ]phenanthrene-4-one (24) and benz [a]anthracene-7,12-dione (B), or isomers, are shown in Figures 3 and 4, respectively. Another possible compound class that shows the (M - 28)' fragment ion is polycyclic aldehydes. However, they would also show a strong (M - 1)+fragment ion (In,which is not observed for any compound in the sample. Nitroaromatic compounds were searched for by E1 mass chromatography. Very weak traces of nitronaphthalene and nitropyrene/nitrofluoranthene were found at right retention times, but no conclusive mass spectra were obtained. Environ. Sci. Technoi., Vol. 16, No. 12, 1982 863
100,
I
500
1000
1500
ZOO0
2500
3000 SCAN
Figure 5. Reconstructed ion chromatogram (NICI)of the moderately polar fraction.
GCMS with NICI Technique. The reconstructed ion chromatogram by the NICI method is shown in Figure 5. The figure clearly demonstrates the selectivity of the NICI technique. Compounds such as aliphatic aldehydes/ ketones show very little electron affinity and hence give no response. The chromatogram is simplified, showing only electron capturing compounds. The compounds characterized by this technique are reported in Table 111. As can be seen from Table 111 polycyclic organic compounds characterized by the E1 technique show response to the NICI technique. The oxygenated compounds show only the molecular ions, and no fragmentation is observed. The presence of PAH-carbonitriles was verified by GC retention times identical with those of authentic standards and by molecular weight. The carbonitriles also show only the molecular ion with no fragmentation. Several nitro-PAH were characterized based on GC retention times and NICI mass spectra which show an intense molecular ion as base peak. The (M- 16)- ion is always present in the spectra of nitro-PAH, due to loss of an oxygen radical. The (M - 30)- ion is present in some spectra, due to a loss of a nitrite radical. The NOz- ion, m/z 46, is a very characteristic fragment of nitro-PAH (19). The most abundant compound with m/z 247 was characterized as 3-nitrofluoranthene based on the GC retention time. This compound is eluted before the isomer 1nitropyrene (26), which was also characterized in the sample. One must be aware of the fact that the electron-capturing process is competitive. If two compounds are eluted into the ion source at the same time, the one with the largest electron-capture cross section will capture most of the electrons. 1-nitropyrene is coeluted with the more abundant benz[a]antraquinone, which could reduce the ionization of 1-nitropyrene, and hence the amount could be underestimated compared to the 3-nitrofluoranthene, apparently equally abundant in this sample. The NICI mass spectra of 9-nitroanthracene and 3-nitrofluoranthene are given in Figures 6 and 7, respectively. To the best of our knowledge this is the first mass spectrometric evidence for nitro-PAH in urban air particles. In addition to nitro-PAH, several oxy-PAH were characterized in the sample. It cannot be excluded that some of these compounds have been formed during the long sampling time by reaction of the corresponding parent PAH with nitrogen oxides (NO,) or by oxidation. However, many of these compounds have been identified also in exhaust from diesel and gasoline engines (9,26,27)and other combustion sources. Furthermore, formation of these compounds may be caused by the possible atmos864
Envlron. Scl. Technol., Voi. 16, No. 12, 1982
Table 111. Compounds Characterized by GCMS with ECNICI Technique compound scan M, 556 148 phthalic anhydride 691 162 methylphthalic anhydride 742 162 methylphthalic anhydride 801 176 dimethylphthalic anhydride 832 176 dimethylphthalic anhydride 879 176 dimethylphthalic anhydride 931 176 dimethylphthalic anhydride 991 173 nitronaphthalene 1046 173 nitronaphthalene 1064 190 trimethylphthalic anhydridea 1108 190 trimethylphthalic anhydridea 1139 206 unknown 1175 180 9-fluorenone 1234 177 acenaphthene carbonitrile 1311 198 naphthalenedicarboxylic anhydride 1340 194 methylfluorenonea 1433 212 methylnaph thalenedicarboxylic anhydridea 1458 212 methylnaphthalenedicarboxylic anhydridea 1482 208 anthraquinone 1570 204 cyclopenta[def]phenanthrone 1581 234 unknown 1598 222 methylanthraquinonea 1646 222 methylanthraquinonea 1687 223 nitroanthracene 1702 203 anthracenecarboni trile 1779 223 9-nitroanthracene 1900 237 methylnitroanthracene 1922 230 benzan throne 1956 230 benzanthrone 2021 227 pyrenecarbonitrile 2121 247 3-nitrofluoranthene 2162 247 1-nitropyrene 2168 258 benz[a ]anthraquinone 2288 254 benzo[cd]pyrenone 2304 272 pyrene-3,4-dicarboxylic anhydridea 2313 254 benzo[ cdlpyrenone 2578 280 di benzofluorenone 2603 280 dibenzofluorenone 2609 278 cyclopenta[ghi Iperylenone 2616 280 dibenzofluorenone 2633 280 dibenzofluorenone 2712 280 di benzofluorenone 2767 308 unknown (ketone) 2836 308 unknown (ketone) 2868 308 unknown (ketone) 2882 304 cyclopenta[ghi]picenone 2908 304 cyclopenta[ghi]picenone 2939 302 benzo[ghi]cyclopenta[pqr lperylenone 2943 304 cyclopenta[ghi]picenone 2986 304 cyclopenta[ghi]picenone a Characterization based on molecular ion only. 100
W
z
4
50
m
1
Figure 6. Mass spectrum (NICI)of scan 1779.
pheric reactions of particle-adsorbed PAH (28,29). Other components of particular interest are the PAHcarbonitriles. Lao et al. have identified fluorene carbo-
100-
50
100
150
200
250
rnlz
Flgure 7. Mass spectrum (NICI) of scan 2121.
nitrile in urban air particles (30). Bjmseth and Eklund identified some PAH-carbonitriles in the working atmospheres of coke and aluminum plants (31). Several PAHcarbonitriles were identified by Dubay and Hites (32)by combustion of pyridine and xylene in a wick-fed alcohollamp burner. The finding of these compounds in the present sample indicates that PAH-carbonitriles may be ubiquitous in the environment as a result of combustion of nitrogen-containing organic material. The mutagenicity of most compounds reported here is unknown. The nitro-PAH are known to be direct mutagens (28,29). A few benzopyrene ketones have been reported to be direct-acting mutagens (33). Pyrene-3,Cdicarboxylic anhydride, characterized in the sample by its molecular ion only, is recently reported as a weak directacting mutagen of a diesel particulate extract (34). Additional efforts should be directed to obtain pure compounds to be tested for mutagenicity. Until now mainly PAH have been analyzed in air particulate samples. Further work should be done to characterize the more polar polycyclic organic compounds in these samples.
Acknowledgments Stephen A. Wise, National Bureau of Standards, is thanked for providing the sample of urban air particles, and Arne Berg, University of Aarhus, Denmark, for the gift of pyrenecarbonitrile.
Literature Cited (1) Talcott, R. E.; Wei, E. T. J . Natl. Cancer Inst. 1977,58, 449-451. (2) Pitta, J. N., Jr.; Grosjean, D.; Mischke, T. M.; Simmon, V. F.; Polle, D. Toxicol. Lett. 1977, 1, 65-70. (3) Daisey, J. M.; Kneip, T. J.; Hawryluk, I.; Mukai, F. Environ. Sci. Technol. 1980, 14, 1487-1490. (4) Mdler, M.; Alfheim, I. Atmos. Environ. 1980, 14, 83-88. (5) Ames, B. N.; McCann, J.; Yamasaki, E. Mutat. Res. 1975, 31, 347-364.
(6) Carnow, B. W.; Meier, P. Arch. Environ. Health 1973,27, 207-218. (7) Tomingas, R.; Voltmer, G.; Bednarik, R. Sci. Total Environ. 1977, 7,261-267. (8) Tokiwa, H.; Kitamori, S.; Takahashi,K.; Ohnishi, Y. Mutat. Res. 1980, 77, 99-108. (9) Wang, Y. Y.; Rappaport, S. M.; Savoyer, R. F.; Talcott, R. E.; Wei, E. T. Cancer Lett. 1978, 5, 39-47. (10) Pederson, T. C.; Siak, J.8. J. Appl. Toxicol. 1981,1,54-60. (11) Lafroth, G. Chemosphere 1978, 7, 791-798. (12) Fisher, G. L.; Chrisp, C. E.; Raabe, 0. G. Science (Washington, D.C.)1979,204, 879-881. (13) Chrisp, C. E.; Fisher, G. L.; Camert, J. E. Science (Washington, D.C.) 1978, 199, 73-75. (14) Wang, C. Y.; Lee, MA.; King, C. M.; Warner, P. 0. Chemosphere 1980, 9, 83-87. (15) Jager, J. J . Chromatogr. 1978, 152, 575-578. (16) Eisenberg, W. C. J . Chromatogr. Sci. 1978, 16, 145-151. (17) Schuetzle, D.; Lee, F. S.-C.; Prater, T. J. Int. J . Environ. Anal. Chem. 1981,9,93-144. (18) Hunt, D. F.; Crow, F. W. Anal. Chem. 1978,50,1781-1784. (19) Ramdahl, T.; Urdal, K. Anal. Chem. 1982,54,2256-2260. (20) Josephson, J. Environ. Sci. Technol. 1981,15,1408-1412. (21) Hoffmann, D.; Wynder, E. L. In “Air Pollution”; Stern, A. C., Ed.; Academic Press: New York, 1968; Vol. 11,p 187. (22) Crow, F. W.; Bjarseth, A,; Knapp, K. T.; Bennett, R. Anal. Chem. 1981,53,619-625. (23) Brumley, W. C.; Nesheim, S.; Trucksess,M. W.; Trucksess, E. W.; Dreifuss, P. A.; Roach, J. A. G.; Andrzejewski, D.; Eppley, R. M.; Pohland, A. E.; Thorpe, C. W.; Sphon, J. A. Anal. Chem. 1981,53, 2003-2006. (24) Gold, A. Anal. Chem. 1975, 47, 1469-1472. (25) Pierce, R. C.; Katz, M. Environ. Sci. Technol. 1976, 10, 45-51. (26) Schuetzle, D.; Riley, T. L.; Prater, T. J.; Harvey, T. M.; Hunt, D. F. Anal. Chem. 1982,54, 265-271. (27) Choudhury, D. R. Environ. Sci. Technol. 1982,16,102-106. (28) Pitts, J. N., Jr.; van Cauwenberghe, K. A.; Grosjean, D.; Schmid, J. P.; Fitz, D. R.; Belzer, W. L., Jr.; Knudson, G. B.; Hynds, P. M. Science (Washington, D.C.)1978,202, 515-519. (29) Pitts, J. N., Jr. Phil. Trans. R. SOC.London A 1979,290, 551-576. (30) Lao. R. C.; Thomas, R. S.; Oja, H.; Dubois, L. Anal. Chem. 1973,45,908-915. (31) Bjrarseth, A.; Eklund, G. Anal. Chim. Acta 1979, 105, 119-128. (32) Dubay, G. R.; Hites, R. A. Enuiron. Sci. Technol. 1978,12, 965-968. (33) Salamone, M. F.; Heddle, J. A.; Katz, M. Environ. Int. 1979, 2, 37-43. (34) Rappaport, S. M.; Wang, Y. Y.; Wei, E. T.; Sawyer, R.; Watkins, B. E.; Rapoport, H. Environ. Sci. Technol. 1980, 14, 1505-1509.
Received for review April 7, 1982. Accepted August 6, 1982. 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).
Envlron. Scl. Technol., Vol. 16, No. 12, 1982 865
