Anal. Chem. 1980, 52, 1825-1828
1825
Gas Chromatographic-Mass Spectrometric Analysis of Chlorination Effects on Commercial Coal-Tar Leachate Katherine Alben Environmental Health Center, Division of Laboratories and Research, New York State Department
Samples of leachate from a commercial coal tar have been analyzed for polycyclic aromatic hydrocarbons (PAHs) by capillary gas chromatography-mass spectrometry, using electronimpact and chemical ionization. Basneutral extracts Contained predominantly the parent PAHs and alkyl- and nitrogen-substituted PAHs. These compounds were considerably less abundant in samples of chlorinated leachate, which Contained, instead, a number of oxygenated and halogenated PAHs.
In public water supply systems, storage tanks and pipes are often coated to prevent corrosion. Coal tar is one of the materials commony used (1-3). The potential for contamination of potable water by the coating material is of concern t o human health and can be assessed by analysis of leachate from the commercial product. Elevated concentrations of parent polycyclic aromatic hydrocarbons (PAHs) were found in the effluent of a storage tank coated with coal tar ( 4 ) . Evidence has also been reported that at least one parent PAH, fluoranthene, can be leached from bituminous linings of distribution pipes ( 5 ) . Without identifying the possible sources of contamination, other investigators have also found low levels (ng/L) of PAHs in potable water systems (6-8). Recent mutagenicity studies indicate that concentrated extracts of water samples collected in distribution systems are more mutagenic than samples collected a t t h e corresponding treatment plants (9). However, the chemical basis for these observations is still not understood. In order to obtain background for more extensive field investigations, we investigated the effects of chlorination on t h e composition of the coal-tar leachate. A major advantage of the commercial coal tar for study is that it contains many compounds whose standards are not readily available. Its leachate thus simulates under controlled conditions the complexity of actual environmental samples. In addition, it can be coated in uniform layers on a well-defined surface area. T h e polarity of water biased by p H is expected to favor leaching of PAHs with polar functional groups. Water supplies typically range from p H 6 to 9 after treatment. Chlorination, as practiced for disinfection, should further modify the composition of PAHs in coal-tar leachate. Potable water is generally chlorinated to leave a residual of about 0.5 mg free chlorine/L. T h e water mains and storage tanks, after installation and maintenance, are disinfected at concentrations of 50,100, or 200 mg free chlorine/L, depending on the mode of application (10). Harrison et al. have shown that the parent PAHs are significantly degraded by free chlorine at 10 mg/ L (11,12). Aqueous chlorination products of standard PAHs include anthraquinone, fluoranthene chlorohydrin, and monochloro derivatives of fluorene, phenanthrene, methylnaphthalene, and methylphenanthrene ( 1 3 ) . This paper deals primarily with identification of baseneutral compounds in the coal-tar leachate, since mutagenicity studies of coal-derived products have generally found activity highest in basic and neutral fractions (14). Results presented 0003-2700/80/0352-1825$01 OO/O
of Health,
Albany, New York
1220 1
illustrate what is to be expected in capillary GC-MS analyses of coal-tar leachate, with chemical ionization (CI) used t o identify unknown PAHs whose functional groups are revealed as fragments by electron impact (EI). EXPERIMENTAL SECTION Sample Preparation a n d Extraction. Samples were prepared in the laboratory by exposing 40-L volumes of tap water (pH 9) t o test panels coated with a commercial coal tar. The procedures for coating the test panels, leaching conditions, and methods of sample extraction using XAD resins have been described previously ( 4 ) . Results obtained with XAD-2 were confirmed by extraction with XAD-4. The larger surface area of XAD-4 gives it a superior adsorption capacity for low-molecular-weight compounds, demonstrated for organic acids (15). For chlorination studies, commercial bleach (sodium hypochlorite solution) was added to provide 50 mg free chlorine/L. When the test panels were removed from the leachate, chlorination was terminated by adding excess sodium sulfite. GC-MS Analyses. Data were obtained on a Finnigan 4000 GC-MS instrument linked to a Nova 3 data system. Organic compounds were separated on commercial glass capillary columns, either a 25-m OV-17 capillary (Applied Science), programmed from 100 "C (1min) to 225 "C (50 min) at 8 "C/min, or a 30-m SE-54 capillary (Supelco), programmed from 100 "C (1min) to 260 "C (45 min) at the same rate. Although the SE-54 column can be operated at higher temperatures, it bled significantly, increasing background levels in the mass spectra. The capillary column was interfaced by a jet separator (250 "C) to the mass spectrometer. Typically, the mass spectrometer was operated in a 70-eV E1 mode with scans from 50 f,o 600 amu every 2 s. Data were also acquired in a CI mode, using methane or isobutane as reagent gas and generally scanning from 100 to 600 amu. RESULTS AND DISCUSSION Typical chromatograms are shown in Figures 1 and 2, and the compounds identified are listed in Table I. In all cases the same results were obtained for leachate samples with and without chlorination extracted on XAD-2 and XAD-4. T h e elution order of the compounds reported in this paper was also found to be the same for the two capillary columns, SE-54 and OV-17, with the exception of one azaarene (cf. Table I, footnote f,. The OV-17 column was found to give somewhat better resolution of the halogen substituted PAHs than the SE-54 column. Base-Neutral Compounds. T h e base-neutral extracts contained mainly the parent PAHs, alkyl-substituted PAHs, and a number of nitrogen-substituted PAHs, or azaarenes. Small amounts of sulfur- and oxygen-substituted PAHs are also present. T h e E1 mass spectrum for each of these compounds had a base peak corresponding to the mass of the parent ion (M+)and often a low-intensity, doubly charged ion (M2+).As expected, CI spectra contained ions a t M + 1, M + 29, and M + 41, with methane as reagent gas, and a t M + 1, M + 43, and M + 57, with isobutane. The azaarenes were differentiated from the other PAHs by the odd mass of the parent ion in t h e E1 spectra and by even-mass adducts in the CI spectra. Relatively abundant fragment ions indicating a loss of 27 or 28 amu were also noted. Two of these compounds with E1 base peaks 153 and 191 amu have been detected in coal tar (16) but have not been reported C 1980 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 52, NO. 12, OCTOBER 1980
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-~
Table I. Compounds Identified in Coal-Tar Leachate 1
peak no.'"
E1 base peak
2 3 4 5
128 154 154 166 178
6
190
7 8 9
202 202 216 226 228 228 2 28
1
10 11
12 13 14 15 16 17 18 19 20
142 142 156 180
21
216
181
182 192
peak sampleb no,a
group and compound parent PAH naphthalene biphenyl acenaphthene fluorene phenanthrene, anthraceneC 4H-cyclopenta[def] phenanthrene fluoranthene pyrene benzofluorened benzofluoranthene benzo[c] phenanthrenee benz[a] anthracenee chrysene, triphenylenee alkyl-substituted PAH %methylnaphthalene 1-methylnaphthalene dimethylnaphthalene me thy lfluorene me thylcarbazole methyldibenzofurand methylphenanthrene, anthracene methylfluoranthene, methylpyrened nitrogen-substituted PAH (azaarenes) quinoline, isoquinoline
B-N, C B-N, C B-N B-N, C B-N, C B-N B-N, C B-N B-N B-N B-N B-N B-N B-N B-N B-N B-N B-N B-N B-N B-N
30 31 32 33
217 217 217 229
34 35
134 184
36 37 38
168 180 181
39 40
182 194
41 42 43
196 208 208
44
162 (164) 200 ( 2 0 2 ) 202 ( 2 0 4 ) 212 (214) 127 (206, 208) 165 (244, 246) 139 (246, 248)
45
46 47 48 49 50
sampleb
group and compound
E1 base peak
nitrogen-substituted PAH (azaarenes) 4H-benzo[def] carbazolee benzo[a] carbazolee benz[ c ] acridinee benz[ c ] acridinee sulfur-substituted PAH benzothiophene di benzothiophene oxygen-substituted PAH di benzofuran fluorenone C,,H,,O (xanthene isomer )d xan thened anthrone (several isomers) xanthone anthraquinone C,,H,O, halogenated-su bstitu ted PAH chloronaph thalene chlorofluorene chlorodibenzofuran chlorophenanthrene bromonaph thalene bromofluorene bromodibenzofuran
B-N B-N B-N B-N B-N B-N B-N, C C C C C C B-N, C B-N, C
C C C C C C C
B-N B-N, C carbazole B-N acridine B-N phenanthridine B-N B-N 27 Cl,H,N B-N azafluoranthenee 28 B-N azapyrenee 29 203 Assumed t o be predominantly phenanB-N = base-neutral; C = chlorinated leachate. a Refer to Figures 1 and 2. threne, ref 4. Identification is tentative, since insufficient standards were available to resolve the possible isomers of C17Hl,and C,,H,,O. e Identification of these compounds and their isomers is based on E1 and CI spectra and on the elution order of parent and substituted PAHs given in ref 21 for SE-52. f Found in both chlorinated and nonchlorinated leachate. However, the elution order of C,,H,N relative t o dibenzofuran is reversed when analyzed in the OV-17 and SE-54 columns. With SE-54, the compound can be obscured if acenaphthene is present in large amounts. 22
23 24 25 26
129 153 167 179 179 191 203
1000~
C11H7Nf
loo(
15
l i RIC
RIC
1 6 40
13 20
m
00
26 4 0
33 20
40 00
T I M E (min)
320
1
6 40
1
1
10 00
1
1 13 2 0
1
1 I640
1
1
20 00
1
1
23 2 0
1
1
26 40
1
1
3000
TIME ( m i d
Flgure 1. Reconstr'uctedion chromatogram for base-neutral compounds
Figure 2. Reconstructed ion chromatogram for base-neutral compounds
in coal-tar leachate at pH 9 (taken on SE-54 column).
in chlorinated coal-tar leachate at pH 9 (taken on OV-17 column).
in previous studies of azaarenes extracted from air particulates and sediments ( 17-19). These compounds are tentatively identified as nitrogen analogues of acenaphthylene (Figure
3) and cyclopenta[deflphenanthrene (Figure 4). Like many other azaarenes, these compounds are isomeric with cyanosubstituted PAHs. However, in keeping with t h e other az-
ANALYTICAL CHEMISTRY, VOL. 52, NO. 12, OCTOBER 1980
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'O01 E1
50-
IO0
i
50
00
m/e (amu)
Flgure 3. E1 and C I mass spectra of C,,H,N unknown compound. Peaks at 168 amu (EI) and 169 amu (CI) are from the tail of dibenzofuran.
100
1
5
4
CI
5c
53
253
m/e (ornu)
Flgure 4. E1 and C I mass spectra of C14H9Nunknown compound. aarenes found in leachate samples, the spectra are interpreted to represent heterocyclic PAHs, with the nitrogen in the ring system. T h e relative distribution of PAHs in the leachate samples is also of interest. The chromatograms presented in this paper suggest that phenanthrene is the predominant parent PAH found. Levels of parent PAHs were previously quantitated in samples of leachate from the test panels (4). Phenanthrene was the major parent PAH and accoclnted for 125 pg/L of the 266 pg/L total for two to four ring parent PAHs. T h e predominance of phenanthrene was also characteristic of solvent (toluene, cyclohexane, dichloromethane, or diethyl ether) Soxhlet extracts of the commercial coal tar and XAD extracts of water samples contaminated with the coal tar ( 4 ) . For the azaarenes, carbazole was predominant. Relatively few water samples have been reported to contain azaarenes (20),but the
!M+Il'
'I'
200
m/e (amu) Figure 5. E1 and C I mass spectra of C&H,O
300
unknown compound.
data of Borwitzky and Schomburg confirm the presence of azaarenes in coal tar (16). I t is noted that the procedures used in these experiments were not optimized for the determination of azaarenes. Leachate studies were performed a t pH 9, the typical p H of potable water in Albany, NY, and other systems which elevate pH to control corrosion. Azaarenes should be leached best under acidic conditions. Chlorination Products. Chlorination significantly modified the distribution of PAHs in leachate samples (Figure 2, Table I). Of the parent PAHs, fluorene became the most prominent, with concentrations of phenanthrene and fluoranthene considerably diminished and with higher-molecular-weight PAHs absent. Only one azaarene (CI1H7N)was found. Oxygen-substituted PAHs, such as dibenzofuran, became more abundant, and several new oxygenated compounds were found in the chlorinated leachate samples. The most unusual spectrum was obtained for a compound with base peak 181 amu by E1 (Figure 5 ) . T h e E1 spectrum suggested xanthene, and a molecular weight of 182 amu was confirmed by CI. However, the compound eluted after phenanthrene; this was too late for xanthene, which should have come just after fluorene (16, 21). The facile loss of 18 amu by CI was also remarkable and was not noted for any of the other oxygenated PAHs. Intermixed with the oxygenated compounds were low concentrations of chlorine- and bromine-substituted PAHs. Mass spectra of the chlorinated compounds were characterized by a base peak corresponding to M+ and an isotope a t M + 2 amu, with intensity approximately one-third the base-peak intensity. For the brominated compounds, however, both E1 and CI gave spectra with base peaks indicating loss of bromine. The parent ion and the M + 2 isotope of equal intensity were nonetheless prominent. Experiments to investigate chloroform produced by chlorination of potable water have also revealed such mixtures of chlorine- and bromine-substituted compounds (22). In general, the presence of oxygenated and halogenated compounds in chlorinated leachate samples substantiates the results obtained by chlorination of' model PAH compounds (13). The capacity of hypochlorite to initiate the oxidation or halogenation of PAHs is evident. It is important to recall
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Anal. Chem. 1980, 52, 1828-1833
that the compounds identified in this work were obtained in base-neutral extracts of leachate samples. Chlorination of coal-tar leachate is also expected to result in formation of PAHs with polar acidic functional groups. I t is interesting to note that such compounds are reported as products of ozonation of parent PAHs in water (23). Further studies of potable water systems for evidence of coal-tar contamination should benefit by screening for the effects reported in this paper. One possible strategy would be to look for the parent PAHs associated with the azaarenes. These compounds would be expected in systems with low concentrations of residual chlorine. Although chlorination appears t o be beneficial in reducing the concentrations of base-neutral PAHs, it can form oxygen- and halogen-substituted PAHs. Evidence for high concentrations of diverse oxygenated PAHs would suggest a further search for associated halogen-substituted PAHs.
LITERATURE CITED (1) American Water Works Association. "Cement-Mottar Lining for Cast-Iron and Ductile-Iron Pipe and Fittings for Water", C104-74; AWWA: Denver, CO, 1974; pp 1-4. (2) American Water Works Association, "Coal-Tar Protective Coatings and Linings for Steel Water Pipelines-Enamel and Tape-Hot Applied", C203-78; AWWA: Denver, CO, 1978; pp 1-28. (3) American Water Works Association, "Painting and Repainting Steel Tanks, Standpipes, Reservoirs and Elevated Tanks for Water Storage", 0102-64; AWWA: New York. 1964; pp 1-24. (4) Alben, K. Environ. Sci, Technol. 1980, 7 4 , 468-470. (5) Crane, R.; Crathorne, 9.; Fielding, M. I n "Hydrocarbons and Halogenated Hydrocarbons in the Aquatic Environment"; Afghan, B., Mackey, D., Eds.;
Plenum: New York, 1980; pp 161-172. (6) Basu, D.; Saxena, J. Environ. Sci. Techno/. 1978, 72, 795-798. (7) Sorrell, R.; Reding, R. J . Chromatogr. 1979, 185, 655-670. (8) Benoit. T.; LeBel, G.; Williams, D. Int. J . Environ. Anal. Chem. 1979, 6, 277-287. (9) Schwartz, D.; Saxena, J.; Kopfler, F. Environ. Sci. Technol. 1979, 13, 1138-1 141, (IO) New York State Department of Health, Division of Sanitary Engineering, "Disinfection of Reservoirs, Standpipes and Tanks After Construction or Repairs", Public Water Supply Guide, New York State Department of Health: Albany, NY, 1973. (11) Harrison, R.; Perry, R.; Wellings, R. Environ. Sci. Techno/. 1976, 70, 1151-1 155. (12) Harrison, R.; Perry, R.; Wellings, R. Environ. Sci. Technol. 1976, 70, 1156-1 160. (13) Oyler, A.; Bodenner, D.; Welch, K.; Liukkonen, R.; Carlson, R.; Kopperman, H.; Caple, R. Anal. Chem. 1978, 5 0 , 837-842. (14) Guerin, M. I n "Polycyclic Hydrocarbons and Cancer": Gelboin. H., Ts'o, P., Eds.; Academic: New York, 1978; Vol. I, pp 3-42. (15) Aiken, G.; Thurman, E.; Malcolm. R.; Walton, H. Anal. Chem. 1979, 51, 1799- 1803. (16) Borwitzky, H.; Schomburg, G. J , Chromatogr. 1979, 170, 99-124. (17) Dong, M.; Locke, D.; Hoffman, D. Environ. Sci. Technol. 1977, 1 7 , 61 2-618. (18) Cautreels, W.; VanCauwenberghe, K. Atmos. Environ. 1976, 70, 447-457. (19) Wakeham, S. Environ. Sci. Techno/. 1979, 73. 11 18-1 123. (20) Coleman, W. E.; Melton, R.; Kopfler, F.; Barone, K.; Aurand, T.; Jellison, M. Environ. Sci. Technol. 1980, 1 4 , 576-588. (21) Lee, M.; Vassilaros, D.; White, C.; Novotny, M. Anal. Chem. 1978, 57. 768-774. (22) Kieopfer, R. I n "Identification and Analysis of Organic Pollutants in Water"; Keith, L., Ed.; Ann Arbor Science: Ann Arbor, MI, 1976; pp 399-4 16. (23) Chen, P.; Junk, G.; Svec, H. Environ. Sci. Techno/. 1979, 73, 451-454.
RECED-ED for review March 17, 1980. Accepted June 19, 1980.
Interlaboratory Comparison of Determinations of Trace Level Hydrocarbons in Mussels S. A. Wise," S. N. C h e d e r , F. R. Guenther, H. S. Hertz, L. R. Hilpert, W. E. M a y , and R. M. Parris Organic Analytical Research Division, Center for Analytical Chemistry, National Bureau of Standards, Washington, D.C. 20234
The results of the determination of trace-level hydrocarbons in mussel tissue homogenates from two different sites are compared among eight laboratories. The values for the concentrations of total extractable hydrocarbons, total hydrocarbons in the gas chromatographic elution range, and indlvidual hydrocarbon compounds generally differed by less than a factor of four. Sample inhomogeneity, storage instability over a nine-month period, and analysis uncertainty contributed to an observed intralaboratory precision (1 a) of f40 % The results are discussed with regard to the reliability and comparability of data currently generated in environmental monitoring programs.
.
A number of laboratories, using a variety of different analytical techniques (1-6), are currently involved in the measurement of fossil fuel hydrocarbons in marine biota. The large number of marine biota analyses being performed in monitoring programs, such as the "Mussel Watch'' ( 7 ) which uses mussels as sentinel organisms for indicating levels of pollutants in U S . coastal marine waters, necessitates the existence of a basis for comparing data. Currently there is only limited knowledge of the comparability of hydrocarbon data for marine biota analyses from This article not subject to U S. Copyright
different laboratories. Farrington et al. (8)have intercalihrated gas chromatographic analyses for hydrocarbons in spiked liver lipid extracts and tuna meal samples and found good agreement with the "true" value among three laboratories. When intercalibrating with natural samples (such as tissue or sediment) rather than spiked samples, the "true" value is unknown and interlaboratory precision is paramount. A first attempt a t intercomparison of hydrocarbon analyses on a natural sample was recently reported by our laboratory (9). In this previous study two intertidal Alaskan sediment samples were homogenized and analyzed by eight different laboratories. Sample homogeneity and analysis uncertainty contributed to an observed intralaboratory precision ( l a ) of about 2 5 3 0 % relative standard deviation for both samples. The ranges of values reported in the intercomparison study for such parameters as aliphatic and aromatic/unsaturated hydrocarbons were found to be one to two orders of magnitude, indicating the high interlaboratory variability of hydrocarbon determinations in a natural matrix. In this paper a similar interlaboratory comparison for hydrocarbon determinations in mussel tissue is described. Two mussel samples, one from a pristine environment in Alaska and the other from Santa Barbara, Calif., near some natural oil seeps, were each homogenized and then analyzed for hydrocarbons by eight laboratories. A prescribed protocol was
Published 1980 by the American Chemical Society
