Environ. Sci. Technol, 1994, 28, 1320-1324
Environmental Monitoring of Polychlorinated Biphenyls Using Pine Needles as Passive Samplers Flenrlk Kylln
Department of Environmental Chemistry, Stockholm University, 106 91 Stockholm, Sweden Eva Grlmvallt
Department of Analytical Chemistry, Stockholm University, 106 9 1 Stockholm, Sweden Conny Ostman'
Analytical Chemistry Division, National Institute of Occupational Health, 171 84 Solna, Sweden
Present address: Analytical Chemistry Division, National Institute of Occupational Health, 171 84 Solna, Sweden.
(9). Scots pine (Pinus sylvestris), a species with widespread distribution on the Northern Hemisphere, has been found to be a suitable monitor of atmospheric pollution (7,8). Usually three or more year-classes of needles can be identified on a single specimen. In a project aimed at mapping the distribution of organochlorine compounds in Europe, data regarding the concentrations of a number of organohalogens in pine needles have been obtained (8). Pine needles were collected in a transect from the FrenchSpanish border in southern Europe, up to the northern border of Sweden in northern Europe. From this data, it was possible to locate a large source of DDT in the southern parts of the former East Germany (8). Some information on PCB was also included. However, the chromatograms obtained for the determination of organochlorines were so complex that the quantification of compounds occurring at low levels, such as individual chlorinated biphenyls (CBs), were unsatisfactory. Presently, there are not any statistical materials regarding atmospheric concentrations of known contaminants such as PCB and organochlorine pesticides (12), and their trends over time are therefore largely unknown. When determining halogenated pollutants in environmental samples, gas chromatography-mass spectrometry (GC-MS) and gas chromatography-electron capture detection (GC-ECD) are the most commonly applied analytical techniques. The electron capture detector offers a high selectivity and low detection limits regarding halogenated pollutants. However, its use is often complicated by the large differences in both concentration and detector response for the compounds of interest. Further, a large number of interfering compounds exhibiting positive or negative ECD responses are present in many samples. This adds substantially to the complexity of the chromatograms. Negative peaks have been a major problem in connection with the analysis of pine needle extracts with respect to PCB (13). Cleanup by solvent extraction, sulfuric acid extraction, and open column chromatography was not sufficient for obtaining a quality GC-ECD chromatogram of the PCB in pine needle epicuticular wax. Thus, a cleanup procedure with a high selectivity toward the compounds of interest had to be developed. By operating a high-performanceliquid chromatography (HPLC) aminopropyl column in the straight-phase mode, hydrocarbons can be separated according to the size of the conjugated a-electron system. Paraffinic and olefinic compounds elute prior to aromatic species. The latter are then separated according to the number of fused aromatic rings (14). These properties have been used for the
1920 Envlron. Scl. Technol., Vol. 28, No. 7, 1994
0013-938X/94/0928-1320$04.50/0
Pine needles were used as passive samplers for monitoring polychlorinated biphenyls (PCBs) in the environment. A method for the determination of PCB in pine needle wax was developed. By applying an HPLC-based cleanup procedure to wax extracts of pine needles, a high selectivity toward PCB was obtained. High precision and accuracy was achieved, as well as high relative (91-108 f 4-8 % ) and absolute overall recoveries (81 i 14%). Pine needle wax from the central and northern parts of Europe were examined. High concentrations of PCBs with a profile shifted toward low molecular species were found in Western Germany (C 9 CBs = 47 ng/g of wax) when compared to the other investigated geographical sites (c 9 CBs = 4-7 ng/g of wax). Introduction A large body of indirect evidence for the long-range atmospheric transport of persistent organic environmental pollutants exists by the presence of residues of these compounds in biota in remote areas. Vegetation in remote areas has been used as a means to characterize atmospheric concentrations of lipophilic air pollutants (1-9). Data on organochlorine residues in various plants have also been used for the modeling of global distribution of these compounds ( I 1. Accumulation of lipophilic organic trace substances in plants is attributed to uptake from the atmosphere (1). Rot uptake followed by translocation within the plant is not significant for substances with log octanol-water partitioning coefficients larger than 3 (10). The cuticles of the green parts of higher plants are covered by a wax layer functioning as a protection against desiccation. This epicuticular wax, which consists mainly of long-chain esters, polyesters, and paraffins (111,has been shown to accumulate lipophilic compounds (2,3). Air contaminants in the vapor phase are adsorbed to and accumulate in the epicuticular wax of conifer needles, thus acting as diffusive samplers (4). The waxy surface of the pine needles also traps particulates and, thus, pollutants associated to the particles to a certain extent. Conifer needles have been used for monitoring both local and regional distribution of lipophilic air pollutants. In this way, the presence of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) has been investigated in the vicinity of wood-preservingsites in the United States
* Corresponding author.
0 1994 Amerlcan Chemlcal Soclety
approximately 1 year before sampling. All the needles collected from Scots pine were of year-class one, collected in the spring/early summer of 1989. In May 1990,needles that ranged from year-class one to year-class eight divided in separate samples were collected from a mountain pine (Pinus mugo) near Zakopane (Tatra Mountains, Poland). Extraction. A total of 20 g of fresh pine needles was immersed in 50 mL of dichloromethane containing 10 ng of the internal standard, CB-189. The sample was shaken for 3 min and then left standing for 48 h. After decanting the solvent, the needles were shaken once more with a fresh portion of dichloromethane. The combined solutions were filtered through a dichloromethane-washed filter paper (Whatman No. 1). After evaporation of the solvent, a hard off-white waxy residue remained. The dry weight was determined by constant weight, after extraction of Experimental Section the wax layer by letting the remaining needles dry in open Chemicals. Individual PCB congeners identified in air. The weight obtained plus the wax weight constituted samples or used for recovery experiments were CB-28 the dry weight. (2,4,4’-trichlorobiphenyl), CB-44 (2,2’,3,5’-tetrachlorobiPreseparation. In order to remove the wax matrix, phenyl), CB-52 (2,2’,5,5’-tetrachlorobiphenyl), CB-99 the extract was dissolved in 1mL of dichloromethane and (2,2’,4,4’,5-pentachlorobiphenyl), CB-101 (2,2’,4,5,5’-penloaded onto a column containing 10 g of dry-packed tachlorobiphenyl), CB-110 (2,3,3/,4’,6-pentachlorobiphe- activated silica gel. The organochlorines were eluted with nyl), CB-118 (2,3’,4,4’,5-pentachlorobiphenyl),CB-138 10 mL of dichloromethane. After evaporation of the (2,2’,3,4,4’,5’-hexachlorobiphenyl), CB-153 (2,2’,4,4’,5,5’solvent by gentle blow-down under nitrogen, the extract hexachlorobiphenyl), CB-156 (2,3,3/,4,4’,5-hexachlorobi- was dissolved in 500pL of benzene:hexane (1:l)and further phenyl), CB-170 (2,2’,3,3’,4,4’,5-heptachlorobiphenyl), and fractionated using a column containing 1g of a dry-packed CB-180 (2,2’,3,4,4’,5,5’-heptachlorobiphenyl) (18). Indimixture of silica ge1:concentrated sulfuric acid (2:l w/w). vidual PCB congeners of 99 % purity obtained from Ultra By elution with 5 mL of benzene:hexane (l:l),the Scientific (North Kingstown, RI) were used as quanorganochlorine fraction was obtained. After adding dodetification standards. The internal standard CB-189 cane as a keeper, the eluate was concentrated to 100-150 (2,3,3’,4,4’,5,5/-heptachlorobiphenyl) (19)and l*C-labeled p L prior to injection on the HPLC. CB-101 (2.45 Ci/mol, 1.55 pCi added to the sample) used Fractionation was performed using an HPLC system for recovery experiments were synthesized at the Departconsisting of a pump (Model 590, Waters Associates, ment of Environmental Chemistry, Stockholm University. Milford, MA), an electrically actuated switching valve Pesticide standards consisted of EPA reference materials. (ELV 7000, WKrannich, Gottingen, Germany), a UV The technical PCB mixture Aroclor 1254 (Monsanto, St. detector (SPD-BAS, Shimadzu, Japan) operated at 254 Louis, MO) was used for testing the analytical procedure. nm, an aminopropyl silica column (p-Bondapak, 300 mm All solvents were pesticide-grade (Fisons, Loughborough, X 3.9 mm, 5 pm, Waters Associates, Milford, MA) and an England) except hexane (HPLC grade, Rathburn Inc., injector (Model 7125, Rheodyne, Cotati, CA) equipped Walkerburn, Scotland), which was distilled in an all-glass with a 200-pL loop. Injection volumes did not exceed 150 apparatus prior to use. The silica gel (Kieselgel60,0.063pL. Hexane was used as the mobile phase at a flow rate 0.200 mm, Merck, Darmstadt, Germany) was Soxhlet of 1.0 mL/min. extracted with dichloromethane during 24 h, dried, and A PCB fraction was obtained by heart-cutting the HPLC activated overnight at 180 “C. Analytical-grade conceneluent between the start of the elution of the CB-153 and trated sulfuric acid was also obtained from Merck. the end of the elution of the last eluting PCB congener, n-Dodecane (Janssen, Geel, Belgium) was cleaned on CB-77 (20). A small number of highly chlorinated PCB activated neutral aluminium oxide (Merck, Darmstadt, congeners, such as CB-204, were shown to elute prior to Germany) prior to use as a keeper in the solvent evaporation steps. The laboratory glassware were washed in acid this PCB fraction (20).However,these CBs were regarded and basic detergents, rinsed with distilled water and to be insignificant for this study since these components ethanol, and then heated to 300 “C overnight prior to use. are minor constituents of the technical PCB mixtures and are also regarded to have low biological activity. After the Sampling. In a program to monitor organic air elution of CB-77,the flow through the column was reversed pollutants by the analysis of pine needles, samples of Scots and the remaining compounds were eluted in a single backpine (Pinus sylvestris) have been collected in the western flush peak. Dodecane was added to the collected PCB and northern parts of Europe (4, 7, 8). Samples were fraction prior to evaporation and subsequent redissolvation collected from pines situated more than 20 km away from in 0.5-1 mL of hexane. the nearest municipal or industrial center and more than In order to investigate the efficiency of the method for 2 km away from any major road. Samples have been collected from pines at the edge of forest stands facing the eliminating possible interferences by other common southwest or from solitary trees on the southwest-facing chlorinated environmental pollutants, the fractionation side with at least 500 m of open land in front of the sampling procedure was characterized using a number of such site. Sampling was primarily done at a height of 2-3 m compound groups. on trees 25-30 years of age. Collection of samples was Gas Chromatography. The gas chromatograph (Varidone in the spring during bud shooting. In this way, the an 3400 or 3700, Varian, Walnut Creek, CA) was equipped youngest needles had been exposed to ambient air for with a split/splitless injector, an electron capture detector, separation of PCDD and PCDF from aliphatic and aromatic hydrocarbons (15, 16) and for cleanup of Polychlorinated biphenyls in marine samples (17). This paper presents an analytical procedure for the selective analysis of PCB in the complex pine needle epicuticular wax matrix. A study on the recovery of PCB congeners has been performed. The method includes normal-phase HPLC in order to isolate a PCB fraction and capillary GC with ECD detection for the separation and quantification of individual PCB congeners. A rather simple method was obtained, making it possible to map the distribution of PCB using the pine needle as a passive sampler. The levels of selected CBs that are often used as indicator compounds are determined in pine needles collected in central and northern Europe.
Envlron. Sci. Technol., Vol. 28,
No. 7, 1994 1321
and a Varian 8100 autosampler. Hydrogen at a column head pressure of 12 psi was used as a carrier gas with nitrogen as a makeup gas at a flow rate of 40 mL/min. The column was a DB-5 (30 m X 0.25 mm, J&W Scientific, Folsom, CAI. Temperature settings for the injection port and the detector were 250 and 360 "C, respectively. An initial column temperature of 80 "C was held for 2 min, followed by a linear temperature increase of 10 "C/min up to a final temperature of 280 "C, which was held for 10 min. All injections were done in splitless mode. Identification of PCB congeners was done by comparison with reference compounds using relative retention and mass spectra (21). All chromatograms were registered, stored, and processed by an ELDS 900 chromatography data system (Chromatography Data Systems Inc., Svartsjo, Sweden). Gas chromatography-mass spectrometry in the negative ion chemical ionization selective-ion monitoring mode was performed on a Finnigan 4500 mass spectrometer equipped with a Finnigan 9610 gas chromatograph. Chromatographic conditions were as given above, except that helium was used as the carrier gas. Methane at a pressure of 0.45 Torr was used as the reactant gas. The ion source was heldat 125"C, and the electron energy was 125eV. Tetrato octachlorobiphenyls were monitored by using three major peaks in each molecular ion cluster. Gas chromatography-atomic emission detection (GCAED) (Hewlett Packard 5890, Avondale, PA) monitoring the sulfur and carbon signals was used for analysis of HPLC fractions with respect to elementalsulfur. The GC column was a HP-1(5 m X 0.53 mm, Hewlett Packard, Avondale, PA). The temperature of the detector was 320 "C. The column temperature program started at 65 "C for 1min, increasing 10 "C/min to 260 "C, which was kept for 10 min. Helium was used both as the carrier gas, at a linear velocity of 30 cm/s, and as the makeup gas, at a flow rate of 30 mL/min. The injection was made using an on column injector. Radioactivity Measurement. Measurement of radioactivity in the recovery experiments was done on a Packard TriCarb 460C liquid scintillation counter (Packard Instruments, Downers Grove, IL). Results and Discussion By a HPLC cleanup method utilizing an aminopropyl silica bonded-phase column, it is possible to remove many environmental pollutants and anthrophogenic compounds that may interfere with gas chromatographic analysis of PCB. An HPLC chromatogram of the fractionation of a pine needle wax sample is shown in Figure 1. In the collected PCB fraction, a number of PCB congeners were easily detected using GC-ECD analysis. Two GC-ECD chromatograms obtained from a sample prior to and after HPLC fractionation are shown in Figure 2. Analysis of the HPLC prefraction and the back-flush fraction showed that most of the interfering material giving rise to negative response in the ECD were found in the prefraction eluting prior to the PCB. Elemental sulfur, s8,which has been shown to be present in higher plants (221, is a possible interference for lower chlorinated CB congeners. To test for S8,fractions from the HPLC were analyzed by GC-AED. This showed s8 to elute in the prefraction. GC-MS analysis was used to confirm the identity of the peaks in the PCB fraction as being PCB compounds. It was found that the large peak eluting at 18.5 min was 1322 Envlron. Scl. Technol., Vol. 28, No. 7, 1994
Figure 1. Fractionatlonof a plne needle wax extract. After collection of a heart-cut fraction Containing the PCB, the flow is reversed, and the remaining material is eluted as one peak.
r
Ib
I
L 17 M
10 M
91 M
_I"
Figure 2. GC-ECD chromatogramof the same pine needle wax sample prior to (a) and after (b) HPLC fractionation.
Table 1. Characterization of Fractions from Aminopropyl Silica Column with Respect to Some Chlorinated Compounds. prefraction
PCB fraction
hexachlorobenzene PCN 33%b aldrin mirex
PCB PCN67%b toxaphene 10% p,p'-DDE a-and y-chlordene heptachlor
back-flush fraction
CP toxaphene p,p'-DDD & p,p'-DDT a-& y-chlordane heptachlorepoxide a-,b-, y-, & &HCH oxychlordane dieldrin & endrin p,p'-methoxychlor transnonachlor 0 PCB, polychlorinated biphenyls; CP, polychlorinated paraffins; PCN, polychlorinated naphthalenes; HCH, hexachlorocyclohexane. b Account to UV response. c Account to ECD response.
p,p'-DDE, which is not possible to remove using this method. A few minor peaks in the PCB region of the chromatogram were shown not to be PCB. The aminopropyl silica column was also characterized regarding the retention of a number of chlorinated environmental pollutants in order to check which chlorinecontaining compounds might appear in a PCB fraction. As shown in Table 1, most of the organochlorine compounds elute in the back-flush fraction. This fraction can thus be collected and used for further analysis of a number of chlorinated pesticides and other organohalogens. Recovery Tests. Absolute recovery for the overall workup procedure was obtained by adding 14C-labeled
Table 2. Recovery of 1qC-Labeled CB-101 after Different Cleanup Steps (n = 5) treatment recovery ( % ) RSD starting material silica gel column sulfuric acid column HPLC cleanur,
100 98 82 81
2 13 14
congener
recovery (%)
CB-52 CB-44 CB-99 CB-110
99 107 104 91
RSD
PCB congener
recovery (%)
4.6 5.1 5.0 4.9
CB-138 CB-153 CB-170 CB-180
102 100 108 95
compound
recovery ( % )
RSD
hexachlorobenzene mirex a-HCH &HCH
105 96 98 71 98 70 97 102 98 101 99 98 99 101
5 3 5 13 5 12 3 3 5
T-HCH
Table 3. Recovery Relative to Internal Standard of Some Selected PCB Congeners Subject to Entire Cleanup Procedure (n = 5)
PCB
Table 4. Recovery of Some Organochlorine Pesticides for HPLC Fractionation (n = 5)
RSD 6.3 4.2 7.8 7.9
CB-101 to a pine needle wax extract. Five replicate analyses were made involving the complete method. Radioactivity was measured by scintillation counting after eachstep in the cleanup procedure (Table 2). The overall recovery was found to be 81 f 14% (n = 5). About 80% of the loss of material was accounted for by the silica gel/ sulfuric acid column separation. This step also accounted for the major variance in absolute recovery. The HPLC fractionation did not introduce any significant additional losses to the workup procedure. It should be pointed out that in order to avoid losses by sample handling in the HPLC fractionation step, it is necessary to dissolve the sample in at least 100 pL of solvent, which requires an injection loop of not less than 150 pL in order to inject the entire sample. The recovery of PCB relative to the internal standard (CB-189)for the entire analytical procedure was tested by using a standard addition procedure. Aroclor 1254, corresponding to approximately four times the levels of the analyzed PCB congeners in a selected wax sample, was added together with the internal standard. The concentration of total PCB as well as eight selected CBs, listed in Table 3, were quantified in both the spiked and unspiked sample after the cleanup procedure. Recovery of the Aroclor 1254 technical mixture relative to the internal standard was found to be 102 f 2%. For the selected CBs, the recovery relative to the internal standard varied between 91 and 108% with relative standard deviations between 4 and 8%,Table 3. The HPLC fractionation procedure was also evaluated regarding the recoveries of the organochlorine pesticides listed in Table 4. Yields in the range of 95-105% were demonstrated for all compounds except for 0- and 6-HCH. These two compounds are sensitive to degradation, especially in a basic environment. Since the aminopropyl column is regarded as a basic ion-exchange column, the reduced yields of these two compounds could be due to dehydrochlorination catalyzed by the stationary phase. However, the recoveries of other compounds, such as a-HCH, r-HCH, and DDT, that also can undergo dehydrochlorination in a basic environment were good. Analysis of PCB in Pine Needle Epicuticular Wax, A pilot study was performed in order to estimate the concentrations of CBs found in pine needle epicuticular wax (Table 5). Six samples of 1-year-old pine needles from central Germany and southern and central Sweden
(3-HCH aldrin dieldrin endrin heptachlorepoxide oxychlordane a-chlordane @chlordane y-chlordene 6-chlordene heptachlor transnonachlor
6 3 4 4 3 4 3 3
100 100 98 97 99 100 100
p,p’-DDT p,p’-DDD p,p’-DDE p,p’-methoxychlor
5 2 2 3
Table 5. Levels of Some Selected PCB Congeners in Pine Needle Epicuticular Waxs Sweden central Germany
south
central
Giessen Bebra Smygehuk Lyngsjo FunLdalen Vemdalen 25.56 CB 28 5.73 CB 52 CB 101 5.38 CB 118 2.43 CB 138 3.75 CB 153 2.27 CB 156 0.27 CB 170 0.85 CB 180 0.43 sum 46.66
0.21 0.42 2.17 0.60 1.65 1.51 0.07 0.11 0.17
0.13 0.70 2.07 1.00 0.82 1.60 0.14 0.17 0.38
6.92
7.02
0.18 0.59 1.31
2.95 0.65 0.72 0.12 0.09 0.14 6.74
0.10 0.33 0.41 1.43 0.51 0.67 0.16 0.10 0.32 4.03
0.10 0.23 0.44 1.32 0.50 0.69 0.10 0.11 0.27 3.77
Concentration in ng of congener/g of dry pine needles. DDE
153
Flgure 3. GC-ECD chromatogram of the PCB fraction obtained from a pine needle sample collected in Smygehuk in southern Sweden. The CB peaks are identified by IUPAC numbers. IS, internal standard. DDE, l,l-dichloro-2,2-bis(4-chlorophenyl)ethene.
were analyzed with respect to PCB using the described method. Five of the samples exhibited similar PCB profiles. A GC-ECD chromatogram of a sample with a typical PCB profile, collected in Smygehuk situated in the south of Sweden, is shown in Figure 3. The sixth sample was collected outside Giessen in Germany, in the vicinity of the Ruhr industrial area. It exhibited a Envlron. Scl. Technol., Vol. 28, No. 7, I994
1323
concentration was found to increase with age. The results from this preliminary study have to be further supported by an extended investigation. Work is in progress in order to determine the concentrations of various lipophilic air pollutants, including PCB, in individual samples in a program aimed at mapping the distribution of organochlorines in Europe. 180 (IS)
19.00
17.00
Acknowledgments
mln
21.00
Figure 4. GC-ECD chromatogram of the PCB fraction obtained from
a pine needle sample collected in Giessen in Germany, in the vicinity of the Ruhr area. The CB peaks are identified by IUPAC numbers. IS,
internal standard. DDE, l,ldichloro-2,2-bis(4-chlorophenyl)ethene. nu9
1
2
3
4
5
6
8
7
Year-class
Flgure 5. Plot showing the accumulation of CB-138 in pine needles of different age.
completely different PCB profile (Figure 4). When comparing the sampling sites using the sum of the concentrations of the nine selected PCB congeners, the concentrations varied from 47 ng/g in central Europe to 4 ng/g in central Scandinavia. I t should be pointed out that some of the determined compounds might coelute with other usually less abundant PCB congeners due to insufficient separation on single capillary columns. On slightly polar columns like 5 % phenyldimethylsilicone, the CBs 28/31,138/163,101/90/84,and 105/132are known to coelute (23). Accumulation of PCB in Epicuticular Wax. To investigate the PCB accumulation in the epicuticular wax of pine needles, eight year-classes of needles from a single tree were analyzed. The samples were collected from a mountain pine growing in the Tatra Mountains, in the vicinity of Zakopane, Poland. In Figure 5, the concentration of one of the dominating CB congeners, CB-138, in the epicuticular wax layer is plotted versus pine needle age. It is our experience from previous investigations of other chlorinated pollutants that the concentrations increase for each year-class, except for the last year-class available (4). In this class, the concentrations decrease in comparison to the previous year. Presumably, this phenomenon is connected to the inception of senescence of the pine needles. A decrease in the accumulated concentration of PCB in the fifth year-class needles was observed. The needles of this year class were muchshorter and stouter than the other year-classes,and it is conceivable that adverse growth conditions have affected the surface properties of those needles. With the exception of the fifth and the last year-classes, the accumulated PCB 1324
Envlron. Scl. Technol., Vol. 28, No. 7, 1994
The authors wish to thank Professor Emeritus Soren Jensen for being instrumental in developingthe pine needle project and for supplying the needle samples. Janis Athanasiadis, Lotta Hovander, and Karel Janak are acknowledged for technical assistance. Useful comments on the manuscript from Ake Bergman are highly acknowledged. This project was financially supported by the Swedish National Environmental Protection Board, Grants 5316191-5 and 532630-9. Literature Cited (1) (1) Calamari, D.; Bacci, E.; Focardi, S.; Gaggi, C.; Morosiniand, M.; Vighi, M. Environ. Sci. Technol. 1991, 25, 1489. (2) Gaggi, C.; Bacchi, E.; Calamari,D.; Fanelli, R. Chemosphere 1985, 14, 1673. (3) Buckley, E. H. Science 1982,216, 520. (4) Strachan, W. M. J.; Eriksson, G.; Kylin, H.; Jensen, S. Environ. Toxicol. Chem. 1994, 13 (3), 443. (5) Thomas, W.; Ruhling, A.; Simon, H. Environ. Pollut. 1984, A36, 295. (6) Herrman, R.; Baumgartner, I. Environ. Pollut. 1987,46,63. (7) Eriksson, G.; Jensen, S.;Kylin,H.; Strachan, W. M. J. Nature 1989, 341, 42. (8) Jensen, S.; Eriksson, G.; Kylin, H.; Strachan, W. M. J. Chemosphere 1992,24, 229. (9) Safe, S.; Brown, K. W.; Donnelly, K. C.; Andersson, C. S.; Markiewicz K. V.; McLachlan, M. S.; Reischl, A.; Hutzinger, 0. Environ. Sci. Technol. 1992,26, 394. (10) Ryan, J. A.; Bell, R. M.; Davidson, J. M.; O'Connor, G. A. Chemosphere 1989,17, 2299. (11) Tulloch, A. P. In Chemistry and biochemistry of natural waxes; Kolattikudy, P.E., Ed.; Elsevier: Amsterdam, 1976; pp 235-289. (12) Strachan, W. M. J.; Eisenreich, S. J. Mass balancing of toxicchemicalsin the GreatLakes: The roleof atmospheric deposition; International Joint Commission: Windsor, Ontario, Canada, 1988. (13) Franich, R. A.; Jakobsson, E.; Jensen, S.; Kroese, H. W.; Kylin, H. Fresenius J. Anal. Chem. 1993, 347, 337. (14) Wise, S. A.; Chesler,S.N.; Hertz, H. S.; Hilpert, L. R.; May, W. E. Anal. Chem. 1982,54, 1764.. (15) Colmsjo, A. L.; Zebuhr, Y. U.; bstman, C. E. Chromatographia 1987,24, 541. (16) Zebuhr, Y.; NU, C.; Broman, D.; LexBn, K.; Colmsjo, A.; Ostman, C. Chemosphere 1989,19, 39. (17) Schantz, M. M.; Parris, R. M.; Kurz, J.; Ballschmiter, K.; Wise, S. A. Fresenius J. Anal. Chem. 1993, 346, 766. (18) Fischer, R.; Ballschmiter, K. Fresenius 2.Anal. Chem. 1989, 335, 20. (19) Sundstrom,G. Acta Chem. Scand. 1973,27, 600. (20) . . Grimvall, E. Ostman, C. Accepted for publication in J. Chromatogr. (21) Mullin, M. D.; Pochini, C. M.; Mc Crindle, S.; Romkes, M.; Safe, S. H.; Safe, L.M. Environ. Sci. Technol. 1984,18,468. (22) Kylin, H.; Atuma, S.; Hovander L.; Jensen, S. Experentia 1994, 50, 80. (23) Wells, D. E.; Maier, E. A.; Griepink, B. Int. J. Environ. Anal. Chem. 1992,46, 265. Received for review November 3, 1993. Revised manuscript received March 21, 1994. Accepted March 28, 1994.' Abstract published in Advance ACS Abstracts, May 1, 1994.
