Anal. Chem. 1980, 52, 159-164
ACKNOWLEDGMENT The authors are grateful to George Downing, Merck & Co., Rahway, N.J., for the gift of all of the antimalarial compounds employed in this study. They also thank James Fronek, Nathan Albert, and Michael McCarthy for technical assistance. LITERATURE CITED A. Gafni. R. L. Modlin. and L. Brand, Siophys. J., 15, 263 (1975). E. Valeur and J. Moirez, J . Chim. Phys., Phys.-Chim. Biol., 70, 500 (1973). W. R. Ware, L. J. Doemeny, and T. L. Nemzek, J . Phys. Chem., 77, 2038 (1973). B. R. Hunt, Math. Biosci., 10, 215 (1971). I.Isenberg and R. D. Dyson, Biophys. J., 9, 1337 (1969). A. Grinvald and I.2. Steinberg, Anal. Biochem., 59, 583 (1974). I.Isenberg in "Biochemical Fluorescence-Concepts", Vol. 1, R. F. Chen and H. Edelhoch, Eds., Marcel Dekker, New York, 1975, Chapter 2. D. M. Rayner, A. E. McKinnon. A. G. Szabo, and P. A. Hackett. Can. J. Chem., 54, 3246 (1976). A. E. McKinnon. A. G. Szabo, and D. R. Miller, J . Phys. Chem., 81. 1564 (1977). H. E. Zimmerman, D. P. Werthemann, and K. S. Kamm, J . Am. Chem. Soc., 96, 439 (1974). H. E. Zimmerman and T. P. Cutler, J . Chem. Soc., Chem. Commun., 598 (1975). C. Lewis, W. R. Ware, L. J. Doemeny, and T. L. Nemzek, Rev. Sci. Instrum., 44, 107 (1973).
(18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30)
159
J. B. Birks and I. H. Munro, Prog. React. Kinet.. 4, 29 (1967). L. J. Cline Love and L. A. Shaver, Anal. Chem., 48, 364A (1976). W. R. Ware in "Creation and Detection of the Excited State", Vol. 1, Part A. A. A. Lamola, Ed., Marcel Dekker, New York, 1971, Chapter 5. M. A. West and G. S.Beddard, Am. Lab., 8(11), 77 (1976). L. J. Cline Love, L. M. Upton. and A. W. Ritter, Anal. Chem., 50, 2059 (1978). L. A. Shaver and L. J. Cline Love, Appl. Spectrosc., 29, 485 (1975). L. A. Shaver and L. J. Cline Love, Prog. Anal. Chem. 8, 249 (1976). A. E. W. Knight and E. K. Selinger, Spectrochim. Acta, Part A, 27, 1223 (1971). A. L. Hinde, B. K. Selinger, and P. R . Nott, Aust. J . Chem., 30, 2383 (1977). R. R. Sokal and F. J. Rohlf, "Biometry", Freeman, San Francisco, 1969, Chapter 5. A. E. W. Knight and E. K. Selinger, Aust. J . Chem.. 26, 1 (1973). H. E. Zimmerman, K. S.Kamm, and D. P. Werthemann. J . Am. Chem. Soc., 97, 3718 (1975). R. F. Chen, Anal. Biochem., 57, 593 (1974). R. F. Chen, Arch. Biochem. Siophys., 172, 39 (1976). I. B. Berlman, "Handbook of Fluorescence Spectra of Aromatic Molecules", 2nd ed., Academic Press, New York, 1971. G. L. Loper and E. K. C. Lee, Chem. Phys. Lett., 13, 140 (1972). G. C. Loper, University of California, Itvine, Calif., private communication, November 1974. T. Tao, Biopolymers, 8, 609 (1969).
RECEIVED for review June 25, 1979. Accepted October 18, 1979. One of the authors (L.A.S.) is grateful for partial support by FMC Corp., Princeton, N.J.
Characterization of Environmental Samples for Polynuclear Aromatic Hydrocarbons by an X-ray Excited Optical Luminescence Technique C. S. Woo,' A. P. D'Silva, and V. A. Fassel" A m e s Laboratory,
USDOE and Department of
Chemistry, I o w a State University, Ames, I o w a 500 7 1
The X-ray excited optical luminescence (XEOL) of a concentrate in n-heptane of the neutral fraction isolated from by-products of coal combustiin and conversion, and from shale and fuel oils has been utilized to obtain profiles of their polynuclear aromatic hydrocarbon content. The advantages of observing the XEOL of these compounds in Shpol'skii solvents to differentiate Isomeric compounds are documented.
A substantial increase is predicted in the utilization of coal for power production and in coal gasification-liquefaction technologies. The products of coal combustion or conversion to gaseous or liquid fuels are known to contain substantial quantities of polynuclear aromatic hydrocarbons (PAHs), nitrogen heterocyclics, sulfur heterocyclics (thiophenes), and oxygen heterocyclics (furans). Several constituents in the above classes of compounds are known to be carcinogens, co-carcinogens and oncogens ( I ) . Thus, the increased utilization of coal will substantially increase the environmental load of the above compounds through particulate and other fugitive emissions. Because the carcinogenicity of such emissions has been found to be enhanced through synergistic effects ( I ) , the cumulative effects on environmental degra'Present address: Chemistry Department, U n i v e r s i t y of N o r t h e r n Iowa, Cedar Falls, Iowa. 0003-2700/80/0352-0159$01 .OO/O
dation and occupational health of these emissions are expected to be of substantial complexity and magnitude. To evaluate the potential impact of this environmental loading, a large number and variety of environmental samples consisting of particulates and products of coal conversion technologies should be characterized. As a result, there is increasing interest in new analytical concepts that may prove useful for the efficient detection, quantitation, and monitoring of the potentially hazardous compounds at trace levels. There have been recent significant advances in the application of new analytical techniques and methodologies to the quantitation of PAHs in environmental samples (2-12). In the discussion that follows, only typical "state of the art" technologies and methodologies are cited, and the references are not exhaustive. In recent years the principal techniques utilized are: thin-layer chromatography (TLC), capillary column gas chromatography followed by flame ionization detection (GC) or mass spectral characterization (GC-MS), gas-liquid chromatography using nematic liquid crystal columns (GLC), and high performance liquid chromatography with fluorescence detection (HPLC). A critical test for any of these analytical techniques is t.he capability to identify and/or quantitate isomeric species, because the PAHs contained in environmental samples usually consist of several isomeric groups, having widely varying carcinogenicity. Typically, an analytical technique should be able to resolve the four-ring isomers, chrysene, benz[a]anthracene (B[a]A), 0 1979 American Chemical Society
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pyrene, triphenylene, and the near isomeric compound fluoranthene. Another group of isomers, namely benzo[a]pyrene (B[a]P), benzo[e]pyrene (B[e]P),and perylene is often found in environmental samples. The individual members of this group are known to have widely varying carcinogenicity, but often are not adequately resolved by the analytical techniques cited above. Thus, chrysene and triphenylene are not adequately resolved by the GC technique ( 5 ) , and the HPLC technique cannot adequately resolve mixtures of either chrysene and B[a]A or perylene and B[e]P (9, 10). If fluorescence detection is used, the overlapping elution bands of these isomeric mixtures can be resolved spectroscopically via a careful programming of the excitation and emission wavelengths. Success has been reported in separating the isomeric species discussed above, as well as others, by GLC when nematic liquid crystal columns are employed (11,12). Unfortunately, the limited stability of the liquid crystal phases a t the moderately high temperatures (-250 "C) utilized in such separations often results in column bleed. Thus, several samples cannot be processed through such columns. A major disadvantage shared by all the analytical techniques cited above is the necessity of employing time-consuming prior isolation of the individual compounds including isomers. Thus, some prior separation of the PAH fraction from complex samples has been necessary. The potential applications of optical luminescence, particularly the sharp line spectra observed at low temperatures under conventional Shpol'skii luminescence (13) or matrix isolation conditions ( 1 4 ) have been extensively evaluated. In a recent paper we reported the observation of the sharp-line luminescence of a selected group of PAH compounds in a Shpol'skii solvent solidified at 90 K and irradiated by X-rays (15) and commented on the relative merits of X-ray vs. ultraviolet excitation. The application of this technique, which we have called X-ray excited optical luminescence (XEOL) to the identification of several PAHs in coal samples has also been reported (16). In this paper, we report further observations that portend an increasing use of this technique for the qualitative identification and quantitative estimation of a broad range of PAHs and aromatic heterocyclics including isomers of these compounds. For the results reported in this paper, prior isolation of the individual components was not required, although our observations show that some prior separations will be necessary on complex samples if more complete screening is desired on the PAH fraction of complex samples. EXPERIMENTAL Apparatus. The relatively simple XEOL spectrometric instrumentation used in these studies has been described (15). Extraction and Identification of PAH Compounds. The procedure described by Giger and Blumer (17)was modified (16) and used to isolate the neutral fraction of PAHs in environmental samples; the three-step separation procedure used is presented in an abbreviated form in Table I. An aliquot of the PAH concentrate in n-heptane was subjected to XEOL examination. Replicate spectra obtained from aliquots of a single sample are reproducible with an error of 5 5 % . Shale oils consist of an extremely complex mixture of organic compounds, and the isolation of the PAH fraction from shale oils is a singularly difficult analytical task (18). In our studies a special procedure was adopted t o isolate the PAH fraction from a shale oil sample distributed by the National Bureau of Standards as a surrogate ieference material. A 0.5-g sample of the shale oil was dissolved in 100 mL of cyclohexane and sequentially partitioned with 1.5 N NaOH and 1 N HCl to remove the acidic and basic compounds. The neutral fraction was then loaded onto an alumina column (acidic, 10% HzO, 30 g) and on eluting with cyclohexane, the PAH fraction was obtained. The cyclohexane eluate was evaporated to dryness. The residue was dissolved in 1 mL of methanol and then subjected to the fractionation pro-
Table I. Separation Procedure for the Isolation of PAHs from Environmental Samples
Sample
I
Soxhlet extraction with cyclohexane I
c
PAH fractionation on Sephadex LH 20 with benzene-methanol (1:1)eluant
A1,O ,-SiO, column chromatography with heptane-methylene chloride eluant I
c
PAH concentrate in n-heptane
XEOL analysis
A D
C
I
B
Flgure 1. X-ray excited optical luminescence of isomeric polynuclear aromatic hydrocarbons in n-heptane. The characteristic spectra of the following compounds are observed. In A: (a)chrysene, (b) pyrene, (c) benz[ a ]anthracene, (d) triphenylene, (e) fluoranthene. In 6: (a) benzo[e]pyrene, (b) benzo[a]pyrene, (c) perylene
cedure shown in Table I, except that the second 50 mL of eluant was collected in 5-mL subfractions. Except for the investigation of solvent effects on the XEOL of dibenzothiophene, all other spectra were obtained in a n-heptane solvent at 90 K. RESULTS AND DISCUSSION It has been emphasized that one of the basic limitations of several analytical techniques used to characterize the PAH content of samples is the difficulty encountered in identifying isomers, which generally have widely ranging carcinogenicity. In Figure 1,the characteristic sharp-line luminescence spectra observed on the X-ray irradiation of the two groups of isomers
ANALYTICAL CHEMISTRY, VOL. 52, NO. 1, JANUARY 1980
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161
a
Flgure 3. X-ray excited optical luminescence of a mixture of 12 PAHs in n-heptane. (1) 2-Methylnaphthalene, (2) chrysene, (3) benz[a]anthracene, (4) benzo[ elpyrene, (5)3-methylcholanthrene, (6) benzo[a]pyrene, (7)anthracene, (8)fluoranthene, (9) coronene, (IO)perylene, (1l ) triphenylene. (12) phenanthrene 5
2
31
I
?c p e r 7 I
nm
Figure 2. A comparison of X-ray excited optical luminescence of
benzo[a]pyrene and benzo[k]fluoranthene in n-heptane are reproduced. The differentiation of isomeric species is clearly seen in the top portions of Figure 1, which shows the composite spectrum of a mixture of 200 ng each of the four isomers chrysene, pyrene, B[a]A, triphenylene, and the near isomer fluoranthene. All of the five compounds can be easily identified in contrast to the difficulties associated with resolving chrysene and B[a]A by HPLC, or chrysene and triphenylene by GC. The lower spectrum in Figure 1shows the distinct features of carcinogenic B[a]P, the mildly carcinogenic B[e]P, and the noncarcinogenic perylene. In this context, the difficulties experienced in separating and identifying the isomeric perylene and B[e]P by HPLC should be recalled (9, 10). Of special interest are the distinct features shown by B[a]P and B[e]P. Under UV excitation, the emission band at 390 nm has usually been employed for the identification of B[e]P. Under X-ray excitation, B[e]P exhibits both fluorescence at 390 nm as well as phosphorescence at 536 nm. The phosphorescence emission is more intense and also occurs in a spectral region where relatively little interference is expected from the luminescence of other PAH compounds. The molecular emission from N2identified in the figure is observed on X-ray irradiation of air in the irradiation chamber. B[a]P and benzo[k]fluoranthene (B[k]F) are known to have similar UV excited fluorescence spectra with their optimum emission a t -400 nm. Figure 2 clearly shows that the two compounds can easily be identified. Because environmental samples often contain a large number of PAH compounds, the feasibility of identifying as many compounds as possible by the XEOL technique was demonstrated by examining a mixture of 12 PAH compounds. In addition to other compounds, this mixture contained the three isomeric groups: B[a]P, B[e]P, perylene; B[a]A,
8
I
550 (nm) Flgure 4. X-ray excited optical luminescence of PAHs extracted from 10 g of particulates collected at the City of Ames power plant stacks. (1) Dibenz[ah]anthracene, (2)benzo[a]pyrene,(3)benzo[ghi]perylene, (4) anthracene, (5) dibenzo[ai]pyrene, (6) perylene, (7)triphenylene, (8) phenanthrene, (9) fluoranthene 350
42:
I
450 Wavelength
chrysene, triphenylene; and anthracene, phenanthrene. Fluoranthene was also present in these mixtures at 20 pg/mL and the concentration of the remainder varied from 2 to 10 pg/mL. The XEOL spectrum of this mixture is presented in Figure 3. In the figure, all the isomeric compounds can be readily identified. Because the major goal of our present study was to obtain the PAH profiles of environmental samples utilizing the XEOL technique, a variety of environmental samples was examined. The PAH profile of a fly ash sample collected in the city of Ames power plant stack is shown in Figure 4. The spectrum represents PAH compounds present in a 0.2-mL aliquot of n-heptane concentrate obtained on processing a 10-g sample. The presence of a relatively strong peak for benzo[alpyrene should be noted. A second sample consisted of air particulates collected at a site within three blocks of the Ames City power plant, while the stack plume impinged the ground. The sample was collected on a 20 cm X 25 cm quartz fiber filter fitted to a high volume sampler, which was operated for 2 h. The spectrum shown in Figure 5 represents PAH compounds present in less than 1/20 of the air particulate sample. In the absence of an extensive library of the characteristic spectra of a large number of PAH compounds, it is not possible to identify all the spectral lines observed. At concentrations of a ppm or less, most PAH compounds exhibit only a few prominent lines. Thus, in the figures we have indicated only those which could be positively identified. For quantitative determination in complex mixtures, as represented by those discussed above, the method of standard additions is preferred (19)so that artifacts induced by energy
162
ANALYTICAL
CHEMISTRY,
VOL. 52, NO. I, JANUARY 1980
!
7
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I
350
Flgure 5. X-ray excited optical luminescence of PAHs extracted from air particulates. (1) Chrysene, (2) dibenz[ &]anthracene, (3) benzo[alpyrene, (4) benzo[gh/]perylene, (5) anthracene, (6) dibenzo[ai]pyrene, (7) coronene, (8) perylene, (9) triphenylene, (10) phenanthrene, (1 1) benzo[e]pyrene
45G +!c elengti
553 1111
Flgure 7. X-ray excited optical luminescence of PAHs extracted from 250 mg of solvent refined coal-process solvent. The spectrum represents PAHs present in only 3 mg of the sample. (1) Chrysene, (2) benz[a]anthracene, (3) benzo[e]pyrene, (4) 3-methylcholanthrene, (5) benzo[a] pyrene, (6) benzo[ghi] peryiene, (7) dibenzo[ai]pyrene, (8) triphenylene, (9) perylene, (IO) phenanthrene, (1 1) fluoranthene
PERYLENE
CORONENE
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F l g m 8. X-ray excited optical luminescence of PAHs extracted from CONC (/Lg/mL)
CONC (p@r L 1
BENZO (A) PYRENE
TRIPHENYLENE 4620 nm
4033 n m
1.7 mg of a tarry residue obtained during an experiment conducted at Morgantown Energy Research Center, Morgantown, W.Va. The spectrum represents PAHs present in only ' l mof the processed sample. (1) Chrysene, (2) pyrene, (3) benz[a]anthracene, (4) benzo[ elpyrene, (5) dibenztahlanthracene, (6) anthracene, (7) benzo[a]pyrene, (8) benzo[ghi]perylene, (9) dibenzo[ai]pyrene, (10) perylene, (1 1) triphenylene, (12) dibenzo[ah]pyrene, (13) phenanthrene, (14) fluoranthene N 3 S E--alz
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I
-
Flgure 6. Calibration curves for coronene, perylene, benzo [a ] pyrene, and triphenylene obtained using the standard addition procedure. The amounts of PAHs present in the original sample are represented by the symbol x
transfer processes or by inner filter effects can be minimized (13). The analytical calibration curves shown in Figure 6 were obtained from a least-squares fit of the data obtained from additions of increasing amounts of a mixture of B[a]P, perylene, triphenylene, and coronene to aliquots of the extract of the air particulate sample discussed above. The results of this study combined with the observation of a strong peak for benzo[ghi]perylene (see Figure 5) indicate the presence of a relatively large amount of coronene and benzo[ghi]perylene in the air particulate sample. Although the original purpose of collecting this sample was to characterize the power plant stack plume that impinged the ground in the vicinity of the plant site, the fact that the sample was collected several blocks away from the plant site suggested that automobile and truck
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Flgure 9. X-ray excited optical luminescence of PAHs extracted from shale oil. (1) Pyrene, (2) chrysene, (3) benzo[e]pyrene, (4) benzo[alpyrene, (5) anthracene, (6) triphenylene, (7) perylene, (8) phenanthrene, (9) fluoranthene
exhausts contributed to the PAH content. This contention was confirmed by earlier observations of relatively high levels of benzo[ghi]perylene and coronene in automobile exhausts (20), in contrast to the levels detected in by-products of coal combustion (21). The profile of PAHs extracted from a sample of solventrefined coal (SRC) process solvent and a sample of gas stream condensate from a coal gasification plant at the Morgantown Energy Technology Center are shown in Figures 7 and 8, respectively. The separation of the PAHs present in the SRC process solvent was a relatively easy task. A known amount of the sample was directly loaded on the Sephadex LH20
ANALYTICAL CHEMISTRY. VOL. 52, NO. 1, JANUARY 1980
i
163
NO 2 Heating 011 L o ~ i s i a n aE X - J I 2 - F O 2
i'
W
> ta _1
W
rT
350
400
450
500
550
600
Wavelength (nm)
Wavelength (nm)
Figure 10. X-ray excked optical luminescence spectra of fuel oils (each sample represents 0.2 mL of 5 mg/mL fuel oil in nhptane). (1) Phenanthrene, (2) chrysene, (3) pyrene, (4) dibenzanthracene, (5)anthracene, (6) perylene, (7) triphenylene, (8) benzo[ elpyrene, (9) fluoranthene
column and subjected to further processing as indicated in Table I to obtain the PAH fraction. The presence of three known carcinogens, B[a]A, B[a]P, and 3-methylcholanthrene in the SRC process solvent is indicated in the spectrum shown in Figure 7. The presence of a large amount of organic matter in the gas stream condensate made the isolation of the PAH fraction a difficult task, as is indicated by the broad background observed in the spectrum of this sample in Figure 8. T o obtain a better separation of the PAH fraction, a more elaborate fractionation procedure would have to be adopted. P A H Profiles of S h a l e a n d F u e l Oil Samples. The diversity of organic compounds present in shale oil samples, as indicated by the work of Hurtubise et al. (18),makes the isolation of a reasonably pure PAH fraction a difficult task. The spectrum shown in Figure 9 represents the PAHs detectable in the sixth and seventh 5-mL subfractions of the second 50-mL eluate from the separation procedure outlined in this paper. The broad spectral background underlying the sharp peaks suggests the presence of other organic compounds not adequately separated from the PAHs in the separation procedure used. The problems associated with oil spill characterization and the diverse analytical methodology required for unequivocal identification of the source of an oil spill has recently been reviewed (22). Recent studies have demonstrated that the improved spectral structure observed with ultraviolet-excited, low temperature luminescence in contrast to room temperature luminescence is a more effective way of fingerprinting fuel oils (23). Because the spectra observed by Fortier and Eastwood are typical of those observed for PAH compounds which are known to be present in petroleum products, we were led to evaluate the potential of XEOL in Shpol'skii matrices as an alternate approach. The fuel oil samples weighing 5 mg were loaded on Sephadex LH20 columns (Sigma Chemical
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Figure 11.
Company) and subjected to permeation chromatography. The PAH fraction present in the benzene-methanol (1:l)eluant was further processed as outlined earlier to obtain the PAH concentrate. The PAH profiles of four different fuel oil concentrates obtained in this way are shown in Figure 10.
ANALYTICAL CHEMISTRY, VOL. 52, NO. 1, JANUARY 1980
184
0
...J
niques cited. T o obtain reliahle quantitative data on "real world" samples. significant improvements in the analytical methodology to isolate PAH fractions or subfractions will no doubt be necessary. This task has been shown to require a substantial effort (27,281. The potential advantages of utilizing the Shpol'skii effect to simultatieoiisly detect several PAHs present in fractions isolated by improved analytical methodology, e.g., HPLC, has been recently demonstrated (29).
u
4 .
ACKNOWLEDGMENT The authors thank Delyle Eastwood, Scott Fortier, and the United States Coast Guard RRrD Center for the supply of fuel oil samples characterized in this investigation. LITERATURE CITEJ) (1) "Environmental, Health and Control Aspects of Coal Conversion: An Information Overview", Braunstein, H. M., Copenhaver, E. D., Pfuderer. H. A,, Eds.; ORNL/EIS-95, Oak Ridge National Laboratory, Oak Ridge, Tenn. 37830, 1977. (2) Pierce. R. C.; Katz, M. Anal. Chem. 1975, 4 7 , 1743. (3) Novotny, M.; Lee, M. L.: Bartle, K. D. J . Chromafogr. Sei. 1974, 12,
QI
a
6
1.
606. (4) Bjbseth, A.; Lunde, G. Am. Ind. Hyg. Assoc. J 1977, 38, 224. (5) Giger, W.; Schaffner, G. Anal. Chem. 1978, 50, 243. (6) Doran, T.; McTaggert, N. C. J . Chromatogr. Sci. 1974, 72, 715. (7) Dong, M.; Locke, D. C. Anal. Chem. 1976, 4 8 , 368.
e -
(8) Dark. W. A.; McFadden, W. t i . : Bradford, D. L J . Chromatogr. Sci.
c
0-
-_
I-
-
CC
4T;C :+3
---
__ 50 C
e f r q t h (nm
Figure 12. Effects of solvents on the structure of dibenzothiophene spectrum under X-ray irradiation. Dibenzothiophene was present at 20 ppm in each solvent
There do not appear to be significant differences in the number 2 fuel oils shown on the left of the figure, but identifiable differences are observed between the number 2,4, and 6 oils. Thus, the technique described in this paper may provide an alternate avenue for characterizing oil spills. XEOL of Other Compounds in Shpol'skii Solvents. Of the nitrogen heterocyclics, several carbazoles are known to be carcinogenic. The spectra of two carcinogenic carbazoles are shown in Figure 11. The spectral differences observed in Figure 11 should facilitate the identification of the two isomers in a mixture. As shown in Figure 12, dibenzothiophene, a carcinogenic compound presumed to be a major component of the organic sulfur compounds in coal, exhibits sharp line spectra in the n-heptane Shpol'skii host but not in either tetrahydrofuran or cyclohexane solvents. Tetrahydrofuran has been reported to function as a Shpol'skii solvent (24). To the best of our knowledge, the spectrum of dibenzothiophene in a n-heptane host is the first report of a Shpol'skii spectrum of this compound. CONCLUSION One of the criteria in the UICC/IAFtC (25,26)specifications for an acceptable analytical method for PAH determination is the capability to identify several components that may be present in mixtures isolated from a sample. The components which should be unequivocally identified and measured are B[a]A, B[a]P, B[e]P, benzo[ghi]perylene, pyrene, B[k]F, and coronene. In this paper, we have demonstrated that the XEOL of PAHs in Shpol'skii solvents can meet the identification criterion, in contrast to most other analytical tech-
1977, 15, 454. (9) Fox, M. A.; Staley, S. W . Anal. Chem. 1976, 4 8 , 992. (IO) Das, B. S.;Thomas, G. H. Anal. Che/n. 1978, 50, 967. (I1) Janini, G. M.; Muschik, G. M.; Schroer, J. A.; Zielinski, W. L.,Jr. Anal. Chem. 1976, 4 8 , 1879. (12) Janini, G. M.; Shsikh, B.: Zielinski. W. L., Jr. J . Ch'hron7atogr. 1977, 132, 136. (13) Kirkbright, G. F.; DeLima. C. G. Analyst (London) 1974, 9 9 , 338. (14) Wehry, E. L.; Mamantov. G. Anal. Chem, 1979, 57, 643A. (15) D'Silva, A. P.; Oestreich, G J.; Fassel, V. A. Anal. Chem. 1976, 4 8 , 915. (16) Woo, C. S.;D'Silva, A. P.; Fassel, V. A.: Oestreich, G. J. Environ. Sci. Techno/. 1978, 72, 173. (17) Giger, W.; Blumer, M. Anal. Chem. 1974, 4 6 , 1663. (18) Hurtubise, R. J.; Schabron, J. F.; Feaster, J. D : Therkildsen, D. H.; Poulson, R. E. Anal. Chlm. Acta 1977, 8 9 , 377. (19) Shpol'skii, E. V. J . Appl. Spectrosc. 1967, 7 . 336. (20) Grimmer, G.; Bohnke, H.; Glaser, A. Zbl. Bkt. Hyg., I. Ab?. Crig. 6. 1977, 164, 218. (21) Natusch, D. F. S.;Wallace. J. R.; Evans, C. A . Sciencel974, 183,202. (22) Bentz, A. P. Anal. Chem. 1978, 50, 655A. (23) Fortier, S. H.; Eastwood, D. Anal. Chem. 1978, 50, 334. (24) Kirkbright, G. F.; DeLima, C. G. Chem P h p . Letf. 1976, 37, 165. (25) Union Internationale Centre le Cancer (UICC), Geneva, Switzerland, Technical Report Series, Voi. 4, 1970. (26) International Agency for Research on Cancer (IARC'). L.yon, France; Internal Technical Report, No. 71/002,1971. (27) Wise, S.A,; Chesler, S.N.; Hertz, H. S.: Hilpert, L. R.; May, W . E. Anal. Chem. 1977, 4 9 , 2306. (28) Guerin. M. R.; Epler, J. L . ; Griest, W. H.; Clark, B R.; Rao, T. K. In "Carcinogenesis-A Comprehenske Survey", Jones, P. W., Freudenthal, R. I., Eds.; Raven Press, New York, 1978;pp 21-33. (29) Colmsjo, A,; Stenberg, U. Anal. Chem. 1979, 51, 145.
RECEIVED for review June 25, 1979. Accepted October 22, 1979. Based on papers presented at the following conferences: Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Cleveland, Ohio, March 1978; Ninth Materials Research Symposium, "Trace Organic Analysis: A New Frontier in Analytical Chemistry", National Bureau of Standards, Washington, D.C., April 1978; International Symposium on the Analysis of Hydrocarbons and Halogenated Hydrocarbons in Aquatic Environment, Hamilton, Ont., Canada, May 1978; Polynuclear Aromatic € 3 ) drocarbons, Third International Symposium on Analysis, Chemistry and Biology, Columbus, Ohio, October 1978. This work was supported by the US.Department of Energy, contract No. W-7405-Eng-82, Office of Health and Environmental Research, Budget Code GK-01-02-04-3.
