Environ. Sci. Techno/. 1984, 18, 386-391
Determination of Polycyclic Aromatic Hydrocarbons in Biomass Gasifier Effluents with Liquid Chromatography/Diode Array Spectroscopy David J. Desllets, Peter T. Kissinger, and Fred E. Lytle Department of Chemistry, Purdue University, West Lafayette, Indiana 47907
Mark A. Horne, Mark S. Ludwlczak, and Robert 6. Jacko" Department of Civil Engineering, Purdue University, West Lafayette, Indiana 47907
Liquid chromatography/diode array spectroscopy (LC/DAS) is used for the determination of polycyclic aromatic hydrocarbons (PAH) isolated from the emissions of biomass gasifiers. The spectrometer is capable of obtaining complete absorption spectra of components as they elute from the chromatograph, thus confirming the identities of pure peaks and mixed or poorly resolved peaks. This technique is especially well suited for the determination of polynuclear aromatics, where many isomers difficult to resolve chromatographically are easily distinguished by their electronic spectra. The instrument is also capable of differentiating between unsubstituted PAH and their methylated analogues, even though methylation does not greatly perturb the electronic nature of the parent hydrocarbon.
Introduction Of the many available alternate fuels used for drying agricultural products, biomass is becoming increasingly attractive (1,2). However, in conjunction with the combustion of any fuel containing carbon and hydrogen, we expect to observe the formation of polycyclic aromatic hydrocarbons (PAH) (3). Because many of these compounds are proven carcinogens, a method is needed whereby the effluents of biomass gasifiers may be examined for PAH content. One of the most effective methods in common use is gas chromatography/mass spectrometry (GC/MS). Although this technique may exhibit a high degree of chromatographic resolution, especially when capillary columns are used, certain isomeric pairs may still prove difficult to separate (4-7). This tends to limit the usefulness of GC/MS due to the inability of a mass spectrometer to routinely distinguish between structural PAH isomers (4, 8). The problem is especially severe when a questionable peak is composed of a mixture of such isomers. In this case, the mass spectrum obtained would exhibit a blending of the already subtle differences in the spectral features. Hence, coeluting or partially coeluting peaks of isomeric composition cannot be conclusively identified and quantified by GC/MS, even by scanning the leading and trailing edges of these peaks. This fact, combined with the relatively low sample throughput associated with capillary gas chromatographic analyses, indicates that a faster and more specific method of determining PAH should be developed. As part of a study undertaken to assess the potential of biomass gasification as a fuel source for the direct drying of grain, it was necessary to characterize PAH emissions in the effluents of experimental biomass gasifiers. Because of the improvement in sample throughput over gas chromatography, reverse-phase liquid chromatography (LC) was employed in these analyses. Also, since the electronic spectra of organic molecules vary considerably with changes in symmetry, structural isomers of the polycyclic aromatic hydrocarbons are, in most instances, easily distinguished by their absorption spectra (9-11). 386 Environ. Sci. Technol., Vol. 18, No. 5, 1984
Because of the improved sample throughput and enhanced ability to distinguish between isomers, liquid chromatography with on-line ultraviolet-visible (UV-vis) absorbance spectroscopy was used to characterize polycyclic aromatic hydrocarbons in the combustion effluents of the biomass gasifiers. The salient feature of this method was the use of a linear photodiode array to obtain the absorption spectra. A description of the method and typical results will be reported in this publication. The complete PAH and particulate emission parametric study of the various experimental and commercial gasifiers will be submitted to an appropriate agricultural engineering journal. Liquid chromatography/diode array spectroscopy is no longer a new technique. The introduction of several types of commercial instruments would seem to ensure its continued popularity. However, only a few articles have appeared in the literature concerning the application of LC/DAS to polycyclic aromatic hydrocarbons, despite their ideal nature as analytes for this technique (9-11). Polycyclic aromatic hydrocarbons possess moderate molar absorptivities in the UV as well as an unusual degree of spectral fine structure. Hence, PAH determinations based on optical spectroscopy (absorption and emission) tend to be both sensitive and selective. Moreover, structural PAH isomers usually bear little spectroscopic resemblance to one another as shown in Figure 1 for benzo[e]pyrene and perylene. This property can be exploited during the analysis of complex mixtures where certain isomeric groups often prove difficult to resolve chromatographically. In fact, as a direct result of the enhanced chromatographic "resolution" achieved by the acquisition of discrete spectra, it may often be possible to perform the determinations without the need for solvent gradient elution. Hence, the photodiode array spectrometer contributes to a more selective determination.
Experimental Section Materials. The organic solvents obtained for this study were reagent grade or better and subsequently distilled or fractionally distilled in an all-glass apparatus. The water was deionized and also distilled in glass. Silica gel, obtained from Fisher Scientific Co., was 60-200 mesh, was activated in a muffle oven overnight at 275 OC, and was stored in a desiccator over anhydrous calcium chloride until needed. The sodium sulfate used in the cleanup columns was purchased from Merck & Co. and was treated in the same fashion as the silica gel. The PAH reference compounds were obtained from a variety of commercial sources and by donation from the Aston Laboratory for Mass Spectrometry at Purdue University. Each compound was shown to be of the proper identity and of high purity by its melting point, absorption spectrum, and mass spectrum. In addition, each reference standard, when injected individually onto the liquid chromatograph, produced a single peak, thereby suggesting
0013-936X/84/09 18-0386$01.50/0
0 1984 American Chemical Society
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Figure 1. Overlay of spectra from benzo[e]pyrene (solid line) and perylene (dashed line) illustrating the large degree of spectral disparity between the two coeluting isomers.
chromatographic purity. Standard solutions were prepared by dissolving weighed amounts of the required hydrocarbons in the appropriate volumes of acetonitrile, toluene, or dichloromethane. These solutions were stored in amber vials a t -20 OC until needed. Apparatus. Mass spectrometry was performed on a Finnigan Model 4000 quadrupole mass spectrometer fitted with a solid probe and equipped with an INCOS data system. The instrument was operated in the electron ionization mode a t 70 eV with a 1.0-s scan time for the comparison of fragmentation spectra of isomeric PAH. The liquid chromatograph was a Bioanalytical Systems Model LC-154. It was furnished with a 25 X 0.46 cm reverse-phase C1, analytical column (Bioanalytical Systems) and a Model 154 UV absorbance detector, utilizing the mercury lines a t 254 nm, from Altex Scientific, Inc. The system was used for routine quantitative analysis. For identification purposes, a second absorbance detector was utilized. It consisted of a Hewlett-Packard 8450A UV-visible spectrophotometer capable of scanning the wavelength region from 200 to 800 nm in 1 s. This microprocessor-controlled spectrometer was equipped with a Model 9875A cartridge tape unit and a Model 7225A plotter for spectral storage and plotting, respectively. The column effluent was directed through an 8-pL flow cell with quartz windows and having a 1-cm path length (Hellma Cells, Inc.). This cell is designed to fit into the standard 1-cm cuvette holders found in most spectrophotometers. It was determined experimentally that a reference cell was not necessary because sample spectra taken with and without a reference cell were virtually identical after base-line correction. Figure 2 is a simplified block diagram of the instrument. Biomass Gasifiers. Two biomass gasifiers, pilot scale and full scale, were tested in this study. Both were downdraft gasifiers designed to dry shelled corn via a direct-fire, batch-in-bin process using residual corn cobs as the sole source of fuel (12). Sample Collection. Particulate matter in the combustion effluents was isokinetically collected by means of a high volume sampling train consisting of a Gelman type A 20 X 25 cm rectangular glass fiber absolute filter with a 4.7-cm diameter sampling nozzle, a 1.4-m3/min blower, and a positive displacement gas meter. This system is capable of collecting 99.98% of the sampled particulates having an aerodynamic diameter of 0.3 pm or larger. Vapor-phase organics were collected in the same sampling train immediately downstream from the high volume
filter. For this purpose, we constructed a stainless steel cylinder 8.6 cm x 3.5 cm i.d. which was filled with XAD-2 resin (Supelco, Inc.) and end-capped with stainless steel screens. This type of constructiop permitted free air flow, but only through the resin bed. All samples were sealed and kept a t -20 "C in the dark until they were to be analyzed. Sample Extraction and Cleanup. The glass fiber filters were extracted for 6 h in a Soxhlet extractor (approximately 30 cycles) with 200 mL of dichloromethane to obtain particulate-adsorbed organics. Vapor-phase organics were collected from the canister of XAD-2 resin in the same fashion. No extraction thimbles were used; the extracts were vacuum filtered before solvent reduction to remove suspended particulate or fiber material. Each dichloromethane extract was reduced in volume to approximately 1-2 mL over steam with a KudernaDanish apparatus. Cyclohexane (4 mL) was added, and the mixture was again concentrated to 3-4 mL to eliminate the remaining dichloromethane. The PAW fraction was isolated from the cyclohexane extract by a modification of the published procedures (13, 14). The mixture was added to a 1.75 X 14 cm column of activated silica gel. This column contained a 1-cm plug of anhydrous sodium sulfate at each end, was slurry packed in dichloromethane, and then was preequilibrated with pentane. After sample addition, the column was developed with 35 mL of pentane to elute aliphatic hydrocarbons. This was followed by 60 mL of 40:60 dichloromethane: pentane which isolated the aromatic and alkylated aromatic hydrocarbons. Interfering polar compounds were left behind on the column. The dichloromethane/pentane fraction was evaporated just barely to dryness at room temperature under a gentle stream of dry nitrogen. This was carried out in a water bath which acts as a heat sink, thereby decreasing evaporation time. Each sample was reconstituted in exactly 1 mL of acetonitrile by sonication for 1-3 min so as to ensure maximum dissolution of the analyte. Finally, these acetonitrile solutions were filtered through a 0.2-pm filter (Rainin Instrument Co., Inc.) and injected onto the liquid chromatograph. Liquid Chromatography and Absorption Spectroscopy. PAH separation was carried out by CI8 reverse-phase liquid chromatography. The mobile phase consisted of 80/20 (v/v) acetonitrile/water a t a flow rate of 1.5 mL/min. The volume injected was 20 pL. All separations were performed at ambient temperature. For purposes of quantitation, peak height at 254 nm was measured and compared to that of calibration curves obtained from standard mixtures. For peak identification, the diode array spectrometer was used to obtain spectra without resorting to stopped-flow conditions. Environ. Sci. Technol., Vol. 18, No. 5, 1984
387
I. Peak Identities for the Sample and Standard 0Table 2 5 Chromatograms in Figures and D
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Flgure 4. Chromatogram obtained from a biomass gasifier particulate emission extract. See Table I for peak identification.
When obtaining full spectra “on-the-fly”, we utilized a 5-9 measurement time with a 1-2-s integration time. The additional 3-4 s between measurements was necessary to facilitate storage of the acquired spectrum on cassette tape. Any number of spectra could be obtained by exchanging an empty tape for a full one in the dual cassette drive during the course of a determination. The entire available wavelength range from 200 to 800 nm was scanned; this range could then be adjusted before hard copies were made. As a rule, 200-300 spectra were obtained for each injection. Once the required number of spectra were collected, they could be examined sequentially on the display screen of the spectrometer. The operator could then make a visual comparison of sample and standard spectra either by utilizing the overlay capabilities of the display or by making hard copies onto the same page.
Results and Discussion Figures 3 and 4 show the separation achieved with this system; peak identification is in Table I. Mixed peaks are, as a rule, composed of isomers. Samples such as the one shown in Figure 4 would be difficult, although not impossible, to fully characterize by conventional GC/MS. With LC/DAS, this characterization can be carried out with relative ease. Note that in the sample chromatogram (Figure 4) there are no peaks due to interfering (non-PAH) compounds. 388 Environ. Sci. Technol., Vol. 18, No. 5, 1984
9 10, H 11 12
13 14, I 15
16 17, J 18,K 19 20, L 21
4
compound name naphthalene acenaphthylene fluorene phenanthrene anthracene fluoranthene pyrene benzo[ a ]fluorene benzo[ b ]fluorene triphenylene benzo[ c ]phenanthrene chrysene benz [ a ]anthracene a methylpyrene an alkylpyrene benzo[j] fluoranthene benzo[ b] fluoranthene benzo[ e ]pyrene perylene benzo[ k] fluoranthene benzo[a]pyrene indeno[ 1,2,3-cd]pyrene benzo[ghi] perylene coronene (found, but not shown in sample chromatogram)
This has been the case for all samples tested, which indicates a sample cleanup procedure that is highly selective toward the isolation of the polycyclic aromatic hydrocarbons. Additional cleanup steps such as preparative thin-layer chromatography and/or column chromatography with Sephadex LH-20 or Florisil, as reported in the literature, were not necessary (11, 15-17). If aliphatic hydrocarbons are contaminating the injected samples, their presence is transparent to the UV detector. It was determined that polar aromatics do not survive the cleanup procedure by mixing a host of phenols, amines, nitro aromatics, esters, and carboxylic acids with standard PAH reference compounds in dichloromethane and subjecting the mixture to the usual cleanup procedure. Only the PAH were recovered, and at an efficiency of 75-100%) depending on the compound. PAH losses occur during sample collection, extraction, and cleanup. Low molecular weight hydrocarbons tend to be susceptible to the greatest losses. During sample collection, particulate and vapor-phase collection efficiencies are less than 100%. Because fly ash is a highly sorptive matrix, extraction efficiencies are also less than 100% (18, 19). Unavoidable sample handling during sampling and cleanup contributes to some losses as well. Finally, simple volatilization and oxidation by a variety of oxidants create the potential for PAH loss throughout all phases of the analysis (20, 21). In an effort to account for contributions to the sample from sources other than gasifier emissions, the blank was fully characterized. Blank filters and XAD-2 resin samples were analyzed along with each batch of gasifier emission samples. These blanks demonstrated that preextraction of the filters and resin was not necessary. Solvent blanks were also determined so that the contribution from filters or resin alone could be calculated by difference. For routine quantitative analysis, the diode array instrument was not used. As shown in Table 11, when monitoring at 254 nm, this instrument exhibited approximately 20-fold higher limits of detection than the dedicated detector at that same wavelength. Because most of the gasifier samples were quite dilute with respect to PAH content, routine quantitation was carried out by the
Table 11. Approximate Limits of Detection for 12 Polycyclic Aromatic Hydrocarbons (Defined for Signal/Noise = 2)' fixed wavediode array, length, ng compound name ng injected injected naphthalene 20 1.5 acenaphthylene 48 4.8 10 0.5 fluorene phenanthrene 2.0 0.2 flu oranth ene 15 0.9 17 1.0 pyrene benzo[ b ] fluorene 8.0 0.4 benz[ a anthracene 6.2 0.4 benzo[ b Ifluoranthene 9.0 0.54 15 0.60 benzo[ h ] fluoranthene benzo[ a ] pyrene 10 0.60 benzo[ghi] perylene 66 3.5 a Mean ratio diode array/fixed wavelength = 16.6; u = 4.06.
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fixed-wavelength instrument using retention time as the only means of peak identification. Recalling that the cleanup procedure produces samples containing PAH only, retention times give an excellent indication of peak identities once they have been previously established by absorption spectroscopy. As an additional check, more concentrated samples were periodically produced in order to confirm the suspected peak identities of the more dilute samples which were beyond the working range of the diode array instrument. Although the diode array spectrometer was characterized by higher limits of detection than the single wavelength instrument, both devices possessed similar sensitivities for the 12 compounds tested. log/log plots of peak height vs. concentration were linear with slopes equal to 1. The linear dynamic range depended on the compound but spanned some 3 orders of magnitude on the average for the fixed wavelength detector and a t least that much for the array instrument. When unknown peaks were to be characterized, standards of approximately the same concentrations as the analytes were injected first. Absorption spectra were obtained a t 5-s intervals and stored on magnetic tape. Then, the sample was subjected to the same procedure. When an unknown spectrum was observed, it could be compared to spectra previously collected at approximately the same retention time. For the parent hydrocarbons, matching
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Flgure 7. Sequence of three spectra obtained across the width of peak 7,8 (trlphenylene, benzo[c]phananthrene) In Flgure 4. The sequence shows the decrease in the trlphenylene contrlbutlon to the observed spectra while the benzo[c]phenanthrene contrlbutlon is Increaslng. This Indicates that the two compounds are actually slightly resolved In time, although only a single peak is observed. Mixed peaks are easily Characterized in thls fashion.
spectra provided conclusive proof of the identity of the unknown on the basis of retention time and spectral pattern. This is shown for pyrene and benzo[a]pyrene in Figures 5 and 6. Alkylated derivatives were distinguishable from the parent compounds, but not from each other. If none of the standard spectra matched the unknown spectrum, or parts thereof, as in the case of a mixture, spectra obtained from the literature were then examined (22). Published spectra obtained from ethanolic solutions correlated well with those collected in 80% acetonitrile. Multicomponent peaks presented much less of a problem to the absorption spectrometer than they would to a mass spectrometer. Choudhury and Bush have shown that the structural isomers, chrysene and benz[a]anthracene, can be spectroscopically "resolved" even though they are unresolved chromatographically (11). These two compounds were also successfully identified in our experiments as were many other coeluting pairs. In fact, all of the multicomponent peaks shown in Figure 4 were resolved spectroscopically. An example of this is shown in Figure 7 which depicts the observed sequence of spectra obtained for the peak comprising the isomers triphenylene and Envlron. Scl. Technol., Vol. 18, No. 5, 1984
389
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benzo[c]phenanthrene. We observe a decrease in the triphenylene component of the spectrum while the benzo[c]phenanthrene component is rising. This is indicative of two compounds slightly resolved from each other in time, but not enough to yield two peaks. Even if the two compounds were to coelute exactly, the observed spectrum would still be the algebraic sum of the component spectra. The instrument makes it possible to subtract the spectrum of each component from the mixed spectrum provided that suitable standards are available. However, as in the case of the triphenylene/benzo[c]phenanthrenepeak, a simple visual comparison usually sufficed. It may be difficult to determine whether an unassigned peak is due to a methylated analogue or a parent hydrocarbon on the basis of electronic spectra alone. However, we have found that spectral differences are often perceptible enough for one to make this distinction. If retention time data are available from reference compounds, the assignment is readily made. Alkyl substitution causes a slight broadening and red shifting of the absorption bands. This shift to longer wavelengths is usually on the order of 3-5 nm for methyl substitution, which is readily resolved by the spectrophotometer. Figure 8 illustrates this with pyrene. Even though the disparity is slight, when the spectrum of the methyl derivative is overlaid with that of the parent hydrocarbon, these differences are readily visualized. When spectral perturbations are combined with retention time changes (methyl substitution of pyrene generates 3-4-min difference in reverse-phase retention time), there is little room left for doubt as to peak identity, especially if alkylated standards are available. However, it should be noted that when more than one methyl homologue exists, their absorption spectra are indistinguishable. That is, 1-methylpyrene, 2-methylpyrene, and 10-methylpyrene cannot be resolved spectrally, although the three are distinct from pyrene itself. This is why the solid line spectrum in Figure 8 is entitled “methylpyrene” only, and not I-, 2-, or 10-methylpyrene. In fact, it is probably a mixture of all three. Despite the many advantageous properties outlined in the foregoing discussion, LC/DAS has some disadvantages, most notably its high detection limits. However, commercial photodiode array spectrometers are now available that are designed specifically as detectors for liquid chromatography. It is assumed that liquid chromatographic detection limits would be lower for such instruments. There is also some difficulty associated with time 390
Environ. Sci. Technol., Vol. 18, No. 5, 1984
resolution. Because data transfer is limited by tape drive speed to one spectrum every 4 s, we sometimes miss a few of the narrow early peaks. Hence, this system could not be used for high-speed LC with 3-pm particulate packing materials. A direct storage in random access memory (RAM) is a better solution. The newer diode array LC detectors do utilize direct storage in RAM but seem to have only a limited amount of memory space available. A third disadvantage with our instrument is that all data analysis and plotting must be performed post-run. Also, real-time data manipulation such as peak integration cannot be carried out while the spectrophotometer is acquiring data. However, in this study, the benefits derived from LC/ DAS atone for some of the liabilities. Temperature gradient GC and solvent gradient LC require lengthy waiting periods in order for the columns to reequilibrate between sample injections. No such waiting periods are necessary with isocratic LC, so sample throughput tends to be greater. The diode array spectrometer allows us to utilize isocratic elution, because the poorer chromatographic resolution is compensated for by the added selectivity of the diode array. Hence, analysis time is shortened with this system when compared to gradient elution. Second, overlapping or mixed peaks are easy to identify and characterize despite the fact that the component compounds are usually isomeric. Differences in the molecular symmetry of isomers yield differences in the spectral features which are readily discernible. Finally, because the data are stored in digitized form, we can utilize any of the many and varied processing routines available with the instrument at any time after the chromatographic run. These routines allow the user to perform derivative spectroscopy and chromatography, logarithmic spectroscopy, spectral addition, subtraction, multiplication, and division, concentration determination by least-squares fitting to standard spectra, peak finding, etc. Multicomponent peaks that cannot be characterized by eye are often resolvable by means of these routines (IO).
Acknowledgments We acknowledge Martin V. Mikelsons and Anthony E. Rottero as well as the members of the Pardue research group at Purdue University for their excellent technical aid and use of instruments. We also acknowledge the Aston Laboratory for Mass Spectrometry at Purdue for their generous donation of some PAH reference compounds. J. R. Barrett and G. H. Foster of the Purdue Agricultural Engineering School are acknowledged for their participation in the grain drying experiments and for the design of the biomass gasifiers. Registry No. Naphthalene, 91-20-3;acenaphthylene, 208-96-8; fluorene, 86-73-7;phenanthrene, 85-01-8;anthracene, 120-12-7; fluoranthene, 206-44-0; pyrene, 129-00-0; benzo[a]fluorene, 30777-18-5;benzo[blfluorene, 30777-19-6;triphenylene, 217-59-4; benzoIcIphenanthrene, 195-19-7; chrysene, 218-01-9; benz[a]anthracene, 56-55-3;benzolilfluoranthene, 205-82-3;benzo[b ] fluoranthene, 205-99-2; benzo[e]pyrene, 192-97-2; perylene, 19855-0;benzo[k]fluoranthene, 207-08-9; benzo[a]pyrene, 50-32-8; indeno[1,2,3-cd]pyrene, 193-39-5; benzo[ghi]perylene, 191-24-2; coronene, 191-07-1; methylpyrene, 27577-90-8.
Literature Cited (1) Bungay, H.R.Environ. Sci. Technol. 1983,17,24A-31A. (2) Jacko, R.B.; Foster, G. H.; Barrett, J. R. Proceedings of the American Society of Agricultural Engineers, Chicago, IL,1982, Paper 82-3523. (3) “ParticulatePolycyclic Organic Matter”;National Academy of Sciences: Washington, DC, 1972; Chapter 3. (4) Futoma, D.J.; Smith, S. R.; Tanaka, J.; Smith, T. E. CRC Crit. Rev. Anal. Chem. 1981, 12, 2.
Environ. Sci. Technol. 1984, 18, 391-394
Ann Arbor, MI, 1979; pp 231-260. (16) Grimmer, G.; Naujack, K.-W.; Schneider, D. Fresenius’ 2. Anal. Chem. 1982,311,475-484. (17) Dunn, B. P.;Armour, R. J. Anal. Chem. 1980,52,2027-2031. (18) Griest, W. H.; Caton, J. E.; Guerin, M. R.; Yeatts, L. B.,
(5) Lee, M. L.; Vassilaros, D. L.; Phillips, L. V.; Hercules, D. M.; Asumaya, H.; Jorgenson, J. W.; Maskarinec, M. P.; Novotny, M. Anal. Lett. 1979, 12 (A2), 191-203. (6) Lao, R. C.; Thomas, R. S.; Oja, H.; Dubois, L. Anal. Chem. 1973,45, 908-915. (7) Lao, R. C.; Thomas, R. S. In “Polynuclear Aromatic Hydrocarbons”; Jones, P. W.; Leber, P., Eds.; Ann Arbor Science: Ann Arbor, MI, 1979; pp 429-452. (8) “Particulate Polycyclic Organic Matter”; National Academy of Sciences: Washington, DC, 1972, Appendix C, p 301. (9) Choudhwy, D. R. In “PolynuclearAromatic Hydrocarbons”;
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Cooke, M.; Dennis, A. J., Eds.; Battelle Press: Columbus, OH, 1981; pp 265-276. (10) James, G. E. Hewlett-Packard Co., Palo Alto, CA, UV/VIS Technical Paper UV-2. (11) Choudhury, D. R.; Bush, B. Anal. Chem. 1981, 53,
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1351-1356. (12) Barrett, J. R.; Jacko, R. B.; Sumner, H. R. Trans. ASAE 1983, 26 (2), 363-366, 371. (13) Wilkinson, J. E.; Strup, P. E.; Jones, P. W. In “Polynuclear
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Aromatic Hydrocarbons”;Jones, P. W.; Leber, P., Eds.; Ann Arbor Science: Ann Arbor, MI, 1979; pp 217-229. (14) Environmental Protection Agency “GuidelinesEstablishing Test Procedure for the Analysis of Pollutants: Proposed Regulations”. Fed. Regist. 1979, 44, 69464. (15) Snook, M. E.; Severson, R. F.; Higman, H. C.; Arrendale, R. F.; Chortyk, 0. T. In “Polynuclear Aromatic Hydrocarbons”;Jones, P. W.; Leber, P., Eds.; Ann Arbor Science:
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Jr.; Higgins, C. E. In ”Polynuclear Aromatic Hydrocarbons: Chemistry and Biological Effects”; Bjerrseth, A,; Dennis, A. J., Eds.; Battelle Press: Columbus, OH, 1980, pp 819-828. Griest, W. H.; Caton, J. E. In “Polynuclear Aromatic Hydrocarbons: Chemical Analysis and Biological Fate”;Cooke, M.; Dennis, A. J., Eds.; Battelle Press: Columbus,OH, 1981; pp 719-730. Lao, R. C.; Thomas, R. S. In “Polynuclear Aromatic Hydrocarbons: Chemistry and Biological Effects”; Bjerrseth, A.; Dennis, A. J., Eds.; Battelle Press: Columbus, OH, 1980; pp 829-839. Lee, F. S.-C.; Pierson, W. R.; Ezike, J. In “Polynuclear Aromatic Hydrocarbons: Chemistry and Biological Effects”; Bjmseth, A.; Dennis, A. J., Eds.; Battelle Press: Columbus, OH, 1980; pp 543-563. Friedel, R. A.; Orchin, M. “UltravioletSpectra of Aromatic Hydrocarbons”; Wiley: New York, 1951.
Received for review August 23,1983. Accepted December 7,1983. This research was supported in part by the U S . Department of Agricu1turelU.S. Department of Energy (Grant 70-59-2181 6-004-1) and in part by the National Science Foundation.
NOTES Polynuclear Azaarenes in Wood Preservative Wastewater Jeanette Adamst and Choo-Seng Giam” Department of Chemistry, Texas A&M University, College Station, Texas 77843
Polynuclear azaarenes in a creosote-pentachlorophenol wood preservative wastewater were analyzed. The total concentration of azaarenes was determined to be 1300 mg kg-’. Potential adverse effects of these compounds on environmental quality and health suggest a need to develop analytical protocols for measuring azaarenes in hazardous wastes. An evaluation of data in the literature indicates that basic polynuclear azaarenes such as quinolines and benzoquinolines may be widespread in the environment. They have been identified on air particulate matter from Europe (1, 2),the United States (3),and the southern North Atlantic Ocean ( 4 ) . Moreover, more recent data indicate that these compounds are also present in ambient air in the vapor phase and at higher levels than previously reported on particulate matter (5). Polynuclear azaarenes have also been found in lake and marine sediments (6-8) and *Address correspondence to this author at the Graduate School of Public Health (IEHS), University of Pittsburgh, Pittsburgh, PA 15261.
t Present address: Pharmacy and Allied Health Professions, Section of Medicinal Chemistry, Northeastern University, Boston,
MA 02115. 0013-936X/84/0918-0391$01.50/0
groundwater adjacent to an underground coal gasification site (9). The presence of these compounds in the environment has been mainly attributed to the use of fossil fuels (6, 7, 10). The occurrence of polynuclear azaarenes in coal tar has been known since the early 1800s (11). They have been identified more recently in both natural and synthetic crudes (12-15) and subsequently derived distillates and oils (16-19). In petroleum oils, the total fraction of basic organic nitrogen has been estimated to range from -0.2 to 0.5% (15). For coal-derived liquids, however, this range may approach -10-20% (1419). In order to understand some aspects of the environmental impact of polynuclear azaarenes, it is important to determine both sinks and environmental sources (energy and nonenergy related). However, relatively little attention has been given to the analysis of these compounds in nonenergy-related hazardous waste streams (20). For example, Lao et al. (21),in their determination of polynuclear aromatic hydrocarbons in a creosote wood preservative sludge, reported data for only two polynuclear azaarenes, benzoquinoline and acridine (7100 and 3500 mg L-I, respectively). Although creosote and benz[ c] acridine have been listed by the US.EPA as hazardous pollutants (22),there are no established analytical protocols in the U S . EPA
0 1984 American Chemical Society
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