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Rao, P. S. C.; Davidson, J. M.; Jessup, R. E.; Selim, H. M. Soil Sci. SOC.Am. J. 1979, 43, 22-28. Schwarzenbach, R. P.; Westall, J. Environ. Sci. TechnoE. 1981,15, 1360-1367.
Freeman, D. H.; Cheung, L. S. Science (Washington,D.C.) 1981,214, 790-792.
Karickhoff, S. W. J . Hydraul. Eng. 1984, 110, 707-735. Karickhoff, S. W.; Morris, K. R. Environ. Sci. Technol. 1985, 19,51-56.
Onishi, Y.; Wise, S. E. Mathematical Model, SERATRA, For Sediment-Contaminant Transport In River and Its Application to Pesticide Transport in Four Mile and Wolf Creeks in Zowa; U.S.Environmental Protection Agency: Athens, GA, 1982; EPA-60013-82-045, p 7. Ambrose, R. B., Jr.; Hill,S. S.; Mulkey, L. A. User's Manual for The Chemical Transport and Fate Model TOXZWASP Version 1; U.S.EnvironmentalProtection Agency: Athens,
GA, 1983; EPA-600/3-83-005, p 13. Lapidus, L.; Amundson, N. R. J . Phys. Chem. 1952,56, 984-988.
Oddson, J. K.; Letey, J.; Weeks, L. V. Soil Sci. SOC.Am. Proc. 1970, 34, 412-417.
Karickhoff, S. W. In Contaminants and Sediments: Analysis, Chemistry, and Biology; Baker, R. A., Ed.; Ann Arbor Science: Ann Arbor, MI, 1980; Vol. 2, pp 193-205. Leenheer, J. A.; Ahlrichs, J. L. Soil Sci. SOC.Am. J. 1971, 35, 700-704.
Hendricks, D. W.; Kuratti, L. G. Water Res. 1982, 16, 829-837.
Chase, R. R. P. Limnol. Oceanogr. 1979,24,417-426. Zabawa, C . F. Science (Washington, D.C.) 1978,202,49-51. Johnson, R. G. J . Mar. Res. 1974, 32, 313-330. Stevenson,F. J. Humus Chemistry, Genesis, Composition Reactions; Wiley: New York, 1982, p 374. Brady, N. C. The Nature and Properties of Soil, 8th ed.; Macmillan: New York, 1974; p 58. Black, C. A.; Evans, D. D.; White, J. L.; Ensminger, L. E.; Clark, F. E. Methods of Soil Analysis: No. 9 in the Series Agronomy; American Society of Agronomy: Madison, WI,
(22) Prasher, B. D.; Ma, Y. H. Am. Inst. Chem. Eng. J. 1977, 23,303-311. (23) Sudo, Y.; Misic, D. M.; Suzuki, M. Chem. Eng. Sci. 1978, 33, 1287-1290. (24) Weber, W. J., Jr.; Liu, K. T. Chem. Eng. Commun. 1980, 6, 49-60. (25) Karger, B. L.; Snyder, L. R.; Horvath, C. An Introduction to Separation Science; Wiley: New York, 1973; p 80-1. (26) Rao, P. S. C.; Jessup, R. E.; Rolston, D. E.; Davidson, J. M.; Kilcrease, D. P. Soil Sci. SOC.Am. J. 1980,44,684-688. (27) Rao, P. S. C.; Jessup, R. E.; Addiscott, T. M. Soil Sci. 1982, 133, 342-349. (28) Crank, J. The Mathematics of Diffusion, 2nd ed.; Clarendon: Oxford, England, 1975; p 93. (29) Gschwend,P. M.; Wu, S. C. Environ. Sci. Technol. 1985, 19, 90-96. (30) Cooney, D. 0.;Adesanya, B. A. Chem. Eng. Sci. 1983,38, 1535-1 54 1. (31) Gschwend, P. M.; Madsen, 0. S.; Wu, S. C.; Wilkin, J. L.;
Ambrose, R. B. "Mass Transport of Toxic Chemicals Between Bed and Water," U. S. Environmental Protection Agency, Technical Report. 1985, In preparation. (32) Chiou, C. T. Environ. Sci. Technol. 1985, 19, 57-62. (33) Satterfield, C. N. Mass Transfer in Heterogeneous Catalysis; Robert E. Krieger Publishing: Huntington, NY, 1981; p 18. (34) Moore, W. J. Physical Chemistry, 3rd ed.; Prentice-Hall: Englewood Cliffs, NJ, 1962; p 180. (35) Chiou, C. T.; Porter, P. E.; Schmedding, D. W. Environ. Sci. Technol. 1983, 17, 227-231. (36) Karickhoff, S. W.; Brown, D. S.; Scott, T. A. Water Res. 1979,13,241-248. (37) Ullman, W. J.; Aller, R. C. Limnol. Oceanogr. 1982,27, 552-556. (38) Connolly,J. P. Ph.D. Dissertation, University of Texas at Austin, 1980. (39) Rapaport, R. A.; Eisenreich, S. J. Environ. Sci. Technol. 1984, 18, 163-170.
1965; p 1367.
Mathews, A. P.; Weber, W. J., Jr. Am. Znst. Chem. Eng., Symp. Ser. 166, 1976,43, 91-98.
Received for reuieu August 29,1985. Accepted January 21,1986. This work was supported by U.S. EPA Contract CR 810472-01-0.
Safe Handling of Chemical Toxicants and Control of Interferences in Human Tissue Analysis for Dioxins and Furans Louls R. Alexander, Donald G. Patterson,' Gary L. Myers, and James S. Holler Division of Envlronmental Laboratory Sciences, Center for Environmental Health, Centers for Disease Control, US. Public Health Service, U.S. Department of Health and Human Servlces, Atlanta, Georgia 30333
The development of a comprehensive analytical program in ultratrace analyses of toxic substances requires a facility specifically devoted to synthesis activities and for making analytical standards. The development of adequate operational procedures for such a facility is described. Environmental monitoring is a key activity in protecting the laboratory worker and the analytical integrity of ongoing studies. A wipe test procedure is described that provides the information needed to pinpoint sources of contamination. Examples of operational problems and remedial actions are described for the development of a parts per trillion dioxin analytical method. Introduction
During the last 2 years, the Division of Environmental Laboratory Sciences, formerly the Clinical Chemistry
Division, Center for Environmental Health, Centers for Disease Control (CDC), has been developing the capability for accurately and precisely measuring 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and the other TCDD isomers in human tissue samples while at the same time synthesizing dioxins and furans for use as analytical standards (1). Any laboratory conducting work with dioxins should have (1)facilities designed to safely handle such hazardous materials and (2) adequate safety guidelines (2). To facilitate the safe handling of these dioxins, CDC has established a Chemical Toxicant Laboratory (CTL) facility (see Figure 1)that permits work on limited quantities of these compounds. Briefly, some of the features of this laboratory include the following: an isolated laboratory quadrant; limited access; separate dressing room facilities; shower/toilet facilities; a seamless vinyl floor; a pass-through compartment; view windows; stainless steel
Not subject to US. Copyright. Published 1986 by the American Chemlcal Society
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preparation; isolate analytical equipment used for highlevel standards. Other subtle, more difficult, problems exist in parts-per-trillion analysis. Examples of problems encountered during the develoDmenta1 Dhase of the analytical method and in the synthetic program within the CTL follow.
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55
is
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ANTE-ROOM
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4qawcT. SHOWER
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Figure 1. Locations of wipe tests (black squares) in the Chemical Toxicant Laboratory.
work surfaces; two 5-ft supply-exhaust type fume hoods; three stainless glove boxes; a special ventilation/ exhaust system. CDC has also established a protocol of strict safety guidelines that describe appropriate work practices in the CTL (3). These guidelines can be separated into five areas: (1) planning, (2) training/education, (3) safe handling technique, (4) environmental monitoring, and (5) disposal of laboratory wastes. The specific area of interest that will be addressed here is environmental monitoring of the laboratory. The need for monitoring is twofold: (1) as an indirect measure of the possible chemical exposure that laboratory personnel may receive and (2) as a measure of possible analytical contamination (4). Many factors contribute to laboratory contamination. Primarily, laboratory contamination occurs because of incorrect handling of samples and standards, improper venting of chemical procedures and analytical instruments, or poor housekeeping procedures. If the laboratory work area is properly monitored from an environmental standpoint, the results can provide an indication of overall laboratory cleanliness. With such monitoring, any point sources of contamination can be identified, and with carefully chosen monitoring locations, the approximate extent of the contaminated area can be determined. The development of analytical procedures at the low part-per-trillion (ppt) level along with the synthesis program has resulted in several problems caused by the ultrasensitivity required in the analysis of the biological tissues. All our experience points to the need for carefully developed procedures and thorough monitoring of the work to ensure that the procedures are followed. Ultratrace analysis requires different quality control procedures to reduce contamination and ensure the validity of the analytical results. Several actions are obvious: maintain instruments dedicated to one method; isolate tissue-sample preparation from the synthesis activities and standard 726
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Experimental Section Analytical System. Instrumental analysis is conducted by using a VG ZAB-2F high-resolution mass spectrometer with a VG 2250 data system and a Hewlett-Packard 5840 gas chromatograph. The analyses are conducted in an isomer-specific mode using a narrow bore (0.25 mm) 60-m SP2330 capillary column. The mass spectrometer is operated in the high-resolution (static RP-10 000 at 10% valley) selected ion recording mode, with perfluorotributylamine providing the lock mass at 313.9839. Peak top jumping is accomplished by stepping the accelerating voltage after any necessary correction during the scan of the lock mass. For quantifying biological samples, five analytical standards that correspond to 0.75-25 ppt of 2,3,7,8-TCDD are used to establish a linear calibration curve. The internal standard is the [l3Cl,]-2,3,7,8-TCDD at a concentration corresponding to 24 ppt in the original sample. Other TCDD isomers are estimated, assuming a relative response factor of 1.0. Biological samples are prepared in a multicolumn cleanup procedure in either the manual (1) or automated (5) mode. Wipe Test Procedures. The CDC environmental monitoring plan for dioxins makes use of wipe samples. This is possible because of the nonvolatile nature of dioxins and the nature of the sample being analyzed. Sample locations are chosen to represent surfaces that employees normally contact during laboratory operations. Transient environmental Contamination becomes apparent by using a well-chosen set of sample locations and repeating the tests periodically. The amount of material actually picked up on a given wipe depends on several factors: (1)the amount of material actually present on the surface being tested; (2) the size of the area wiped; (3) the size of the wiping device; (4) the force applied while wiping; (5) the presence of moisture; (6) the compatibility between filter paper and the material being sought. The samplingtechnique consists of wiping a surface area of about 25 cm X 25 cm with a circle of dry Whatman glass microfiber filter paper and then analyzing the amount of contaminant picked up. The wipe sample is extracted with a 50/50 mixture of hexane-methylene chloride. An internal standard solution of 13C-labeled 2,3,7,8-TCDD is added. An aliquot of the extract is put through a cleanup procedure to separate the dioxin isomers from possible interfering substances and other compounds picked up off the surfaces during the wiping. The cleanup procedure consists of two columns arranged in tandem. The first contains acidified silica gel and the second activated alumina. The sample is collected and analyzed by high-resolution gas chromatography/mass spectrometry (GC/MS). Results and Discussion Synthesis Program. During the early months of operating within the CTL, several compounds were synthesized and/or used in synthesis. For safety purposes, initial work involved the synthesis and purification of the 1,2,3,4-TCDDisomer which is at least 500 000 times less toxic than the 2,3,7,8-TCDD isomer (6, 7). After gaining some experience working in the CTL, we began to synthesize and purify 2,3,7,8-TCDD. During this period we also performed, in the CTL, the procedure to attach 1-
Table I. Estimated TCDD (ng, 25 cm location anteroom floor changing room floor exterior hallway glovebox G1 exterior bench top near hood 13 floor near hood 13 pass through knob analytical balance knob window sill (near HPLC)
X 25
Table 11. Estimated TCDD (ng,25 cm
cm)
TCDD 1,3,7,8 1,4,7,8 2,3,7,8 1,2,3,4 ND” ND ND ND 0.020 0,087 ND 1.40 ND
0.163 ND 0.033 0.046 0.088 0.230 ND 3.30 ND
ND ND ND 0.047 0.106 ND 0.04 4.10 0.126
4.38 0.96
0.100 0.026 0.036 1.87 0.12 1.70 ND
“ND = none detected.
amino-3,7,8-trichlorodibenzo-p-dioxin to BSA protein backbone; dialysis and lyophilization followed, and these procedures were also performed within the CTL. During this period, we had to remove the lyophilizer from the CTL so that the manufacturer could service it under the warranty. According to our safety protocol, wipe tests to determine the extent of contamination present are required before any equipment is removed from the CTL. Wipe tests were therefore run. The results from wipe samples taken from the exterior surface of the lyophilizer were positive for 1,2,3,4-TCDD. To determine whether this was a point source contamination or part of a larger problem, we wipe tested the entire bench top above the lyophilizer next to the pass through compartment (see Figure 1). The benchtop was also positive for 1,2,3,4-TCDD. The CTL protocol requires that all work in the CTL cease when wipe tests indicate contamination above a preset level. Since this was our first encounter with such wipe tests and no action level had been set, we decided that all work in the CTL would stop and the CTL was shut down. To get an estimate of any remaining contamination in the CTL, nine wipe samples were strategically taken from selected areas within the CTL and tested. Figure 1indicates where the wipes were done and the results are presented in Table I. The origin of the 1,2,3,4-TCDDand the 2,3,7,8-TCDD can be explained; however, analysis also indicated the presence of 1,3,7,8-TCDDand 1,4,7,8-TCDD. Upon first examination, the origin of the 1,4,7,8-TCDD and the 1,3,7,8-TCDD could not be identified. No combination of the compounds being used in the synthesis work could produce the 1,4,7,8-TCDD. Further investigation showed that the starting material l-amino-3,7,8-trichlorodibenzop-dioxin (purchased from a commercial source) contained as trace impurities the 1,3,7,8-, 1,4,7,8-,and 2,3,7,8-TCDD isomers. The results of the wipe tests show that the levels are extremely low. We analyzed these tests by using a method that has a lower limit of detection at the low tenths of a part per trillion. This level can be observed by only the most sensitive mass spectrometers. Although the overall level of contamination does not appear to be significant, the patterns of contamination do raise concerns about our hazards control procedures. Considering the strict guidelines that control the operations in the CTL, the extent of general contamination was somewhat surprising. Review of the contamination pattern indicated three problems areas: (1)the working area in front of the fume hood; (2) the control knobs of the analytical balance; (3) the entrance and exit areas of CTL. The operational procedure for the dioxin safety protocol requires that all synthesis work be performed in a glovebox. The synthesized crude material was then removed and transferred to the fume hood to be purified by recrystallization. After the recrystallization procedure, the purified material still under the fume hood was transferred to a
location blank outside CTL (area near vortex blender used to prepare samples) HPLC system CTL floor in front of hood 13 anteroom floor
X 25
cm)
TCDD 1,3,7,81,4,7,8 2,3,7,81,2,3,4 ND ND
ND ND
ND ND
ND ND
ND ND ND
ND ND ND
11’ 0.40
ND 0.07
0.25
0.01
Average of three analyses.
preweighed vial. Before removing the vial, the chemist cleaned the outer surface of the vial and the outer surface of the protective gloves. The vial was then transferred to the analytical balance for final weighing. The contamination on the floor near the fume hood probably came from the purification procedure and the crystals that adhered to the gloves and were not removed during the cleaning step. This is further evidenced by the fact that the contamination appeared greatest on the knobs of the analytical balance, which all the chemists contacted regardless of the synthesis work being performed. The contamination of the anteroom floor was not surprising, since chemists remove their protective laboratory clothing in the anteroom before entering the change room. Finding any contamination in the change room-and particularly in the hallway outside the entrance to the CTL-was, however, most alarming. This indicated that our controls for containing contamination within the CTL were not functioning properly. Upon further investigation, we found that the chemists had, for their personal convenience, made a minor modification in the procedure for removing their protective clothing. The receptacle for contaminated laboratory clothing had been moved from the anteroom to the change room. The chemists were removing their protective clothing in the proper area, but were then carrying it to the change room for disposal. In response to the wipe test results, we changed CTL procedures in several ways: (1)all outer gloves, once inserted into a fume hood, must be removed as the hands are being withdrawn from the hood and a new outer pair of gloves must be put on once the hands are outside the hood; (2) the analytical balance must be cleaned after each weighing procedure; (3) a demarcation line in the anteroom has been established beyond which no outer protective clothing articles will pass; (4) absorbent “sticky” pads have been placed at the exit door of the CTL and at the demarcation line to help trap particulate matter on the bottom of shoe coverings; (5) each individual must wear two sets of boots over the shoes while within the CTL area. When exiting the CTL, the person must take off the outer pair of boots in the anteroom. The person may then discard the jumpsuit, or hang it up, and discard the second pair of boots while standing on the “sticky pads” at the demarcation line. This procedure should ensure that no contaminant from the anteroom floor reaches the change room. To decontaminate the CTL, we wiped down all horizontal surfaces with methanol. The decision was that immediately after 2,3,7,8-TCDD had been synthesized, the CTL would be scrubbed again with methanol and a series of strategic wipe tests performed to verify decontamination. During this period the synthesis and recrystallization of 2,3,7,8-TCDD was conducted within a glovebox. The crystalline isomer was filtered in the hood, and some purification was conducted on the HPLC system. The results of these wipe tests are shown in Table 11. No 1,3,7,8Environ. Scl. Technol., Vol. 20, No. 7, 1986
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Table 111. Estimated TCDD (ng,25 cm location CTL floor (before cleanup) CTL floor (after one cleanup) CTL floor (after two cleanups)
X
25 cm)
TCDD 1,3,7,8 1,4,7,8 2,3,7,8 1,2,3,4 ND ND ND
ND ND ND
0.80 0.02 ND
ND ND ND
TCDD or 1,4,7,8-TCDD was found. This was to be expected, since no work in the CTL on the l-amino-3,7,8trichlorodibenzo-p-dioxinhad been done since the last series of wipe tests. The area wipe-tested on the HPLC used to purify the 2,3,7,8-TCDD was just under the injection system. When we investigated the high results, we found a small amount of leakage around the injection area. None of the CTL workers touch this area. These wipe tests were performed after the CTL had been wiped down with methanol, except for the CTL area under the HPLC injection system. The levels found after the cleanup do not indicate that the methanol procedure is highly efficient for decontamination. A new decontamination procedure with toluene was used. It involves (1) applying toluene to the area, (2) wiping the area with a paper bath towel to absorb the toluene, and (3) wiping the area again with a new towel. Table I11 demonstrates the effectiveness of the new procedure. The result of a single wash resulted in a 40-fold decrease in the amount of contamination remaining on the surface. Repeating this procedure reduced the contamination below the detection level. On the basis of these preliminary results, the CTL was wiped down (all horizontal surfaces, including floors) according to the new procedure. The HPLC area in particular was thoroughly cleaned, since during the last series of wipe tests it was found to be the most highly contaminated area. The efficiency of this decontamination procedure is being thoroughly investigated, as well as the possibility of using a wet (toluene-soaked filter paper) rather than a dry wipe test procedure. Analytical Program. As we developed an analytical method for the analysis of dioxins and furans in the low ppt level, we found several analytical problems that were associated with the synthetic program. The analysis of high-level samples before ultratrace work may result in problems of carryover or contamination. In one instance, the mass chromatogram of an analytical standard with only 25 ppt of 2,3,7,8-TCDD exhibited a second peak corresponding to 7.3 ppt of 1,3,6,8-TCDD. Apparently, the previous run, an analysis of 1 ng of the 1,3,6,8 isomer in the full-scan mode, resulted in contamination of the analytical standard. A second instance occurred with the use of a pipetor with a disposable plastic tip. After being used in dispensing 1pg of various TCDD isomers for analytical standards, the pipetor was used to spike the internal standard into a series of tissue samples that were being reanalyzed to provide duplicate data. Upon review of the mass chromatograms,the samples were observed to be contaminated with as much as 5 ppt of the extraneous TCDD isomers. These isomers were not present during the first analysis of the specimens. Although disposable plastic tips were used, carryover was observed with this equipment. Thus, the use of analytical equipment in this fashion threatened the integrity of the analytical system. While trying to identify the source of the 1,4,7,8-TCDD isomer in wipe tests within the CTL, we prepared a sample for mass of the l-amino-3,7,8-trichlorodibenzo-p-dioxin spectral analysis (see Figure 2) by concentrating the sample in a hood. The concentrating apparatus was later used 728
Envlron. Sci. Technol., Vol. 20, No. 7, 1986
TRACE COMPOUNDS IN TRlCHLOROAMlNODlOXlN 1478
Figure 2. Case of the foreign peaks. The source of laboratory contamination is indicated by the identification of trace contaminants that serve as marker compounds. The upper mass chromatogram was obtained in the wlpe testing procedure. The lower mass chromatogram was obtained from the extract of a commercially available amlnotrichlorodibenzodloxln.
(after thorough cleaning with a solvent) to concentrate a series of three biological method-development samples. The 1,4,7,8-TCDD isomer appeared in these biological extracts at the 0.1-2 ppt level in spite of the washing precaution (see Figure 3). After establishing the TCDD chromatographic window and a 2,3,7,8-TCDD isomer specific method, we found, for most samples, several early eluting peaks at varying concentrations, regardless of the matrix. The relative retention times indicated that these peaks were 1,3,6,8- and 1,3,7,9-TCDDisomers. Neither of these compounds had at that time been synthesized or handled in pure form in the laboratory, which suggested an origin other than ongoing analytical activities. The two peaks maintained the same relative intensity ratio, indicating a single source. After much effort, we have shown that these isomers were present in a phenolic-based cleaning solution (see Figure 4) used for washing the floors in the building (8). Substituting another cleaning agent, preparing a new supply of chromatographic materials, and moving the sample cleanup activities have eliminated these artifacts. Summary and Conclusions The wipe tests proved to be a very reliable mechanism for monitoring laboratory contamination. When carefully reviewed, results of these tests also indicate and pinpoint problems with control procedures designed to minimize contamination. Wipe test samples are analyzed by using the same high-resolution GC/MS procedure used to analyze adipose samples for dioxin. This procedure is time consuming and very disruptive to the research efforts re-
SYSTEM BLANK
1234
u
0 HRS 30 MlNS 2 SECS
0 HRS 53 MlNS 35 SECS
CHROMATOGRAPHIC SEPARATION OF TCDD ISOMERS
1234
1368
il 0 HRS 30 MlNZ
ECS
0 HRS 53 MlNS 35 SECS
368
CLEANING SOLUTION EXTRACT 1234
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0 HRS 30 MlNS 2 SECS
1478
x o . 1 ppt.
I\
Figure 3. Mass chromatograms for ion 322 depict the contamination of extracts from three quality control samples followlng the shared use of a sample evaporator. The 2,3,7,8- and 1,2,3,4-TCDD are present in the QC materlai; the 1,4,7,8-TCDD originates from a previous sample prepared by using the sample evaporator.
lying on the mass spectral laboratory for results. Nevertheless, our experience shows that any program that combines high-level standards with low-level (ppt) analysis must dedicate research time to problem solving. Often situations may be explained by a knowledge of chronological events, both in laboratory work and in instrumental analysis. Therefore, both comprehensive laboratory notebooks and complete instrument log books are critical in understanding developmental problems. The best data for problem solving is provided by the most sensitive and specific analysis. For example, the 1,3,6,8-TCDD artifact was usually observed below 1ppt, but a knowledge of the widespread occurrence of this compound helped to establish the source as a cleaning compound. Similarly, the observation of the 1,4,7,8-isomer, only possible in an isomer-specific mode, was the key to establishing the origin of several isomers as external to the laboratory work. Finally, some of these problems may be extremely difficult
0 HRS 53 MlNS 35 SECS
Figure 4. Case of the ubiquitous peaks. These mass chromatograms demonstratethat the source of two TCDD laboratory contaminants is a commercial soap that contains a disinfectant.
to resolve. Several chemists worked several months to demonstrate the artifacts in the cleaning solution.
Acknowledgments Robert Hill and Larry Needham were major contributors to the safety protocol for CTL operations and to procedures for the safe handling of dioxins, respectively. The mass spectroscopic analyses of wipe tests were conducted, in part, by Ralph O’Connor. Elizabeth Barnhart conducted the wipe tests in the CTL, and Don Groce prepared the samples for instrument analysis. R e g i s t r y No. 1,2,3,4-TCDD, 30746-58-8; 1,3,7,8-TCDD, 50585-46-1; 1,4,7,8-TCDD, 40581-94-0; 2,3,7,8-TCDD, 1746-01-6; 1,3,6,8-TCDD, 33423-92-6; 1,3,7,9-TCDD,62470-53-5; l-amino3,7,8-trichloro-p-dioxin, 62782-11-0.
Literature Cited (1) Patterson, D. G.; Holler, J. S.; Lapeza, C. R., Jr.; Alexander, L. R.; Groce, D. F.; O’Connor, R. C.; Smith, S. F.; Liddle, J. A.; Needham, L. L. Anal. Chem. 1986,58, 705-716. (2) Young, A. L. A Review of Laboratory and Waste Management Guidelines for Toxic Chlorinated Dibenzo-pDioxins and Dibenzofurans. Environmental Science Research: Human and Environmental Risks of Chlorinated Dioxins and Related Compounds; Tudor, R. E.; Young, A. L.; Gray, A. P., Eds.; Plenum: New York, 1983; Vol. 26, p 667. Envlron. Sci. Technol., Vol. 20, No. 7, 1986
729
Environ. Sci. Technol. 1986, 20,730-735
Clinical Chemistry Division “Center for Environmental Health, Safety and Operations Manual for the Chemical Toxicant Laboratory”;Centers for Disease Control, Atlanta, GA, 1984. Hileman, F. D.; Mazer, T.; Kirk, D. E. A Program for Monitoring Potential Contamination in the Laboratory Following the Handling and Analyses of Chlorinated Dibenzo-p-dioxins and Dibenzofurans. Environmental Science Research: H u m a n and Environmental Risks of Chlorinated Dioxins and Related Compounds; Tudor, R. E.; Young, A. L.; Gray, A. P., Eds.; Plenum: New York, 1983;Vol. 26,p 697. Lapeza, C. R.; Patterson, D. G.; Liddle, J. A. “An Automated Apparatus for the Extraction and Enrichment of 2,3,7,8TCDD in Human Adipose Tissue”; Presented at the Sci-
entific Computing and Automation Conference and Exposition, Atlantic City, NJ, May 1-3, 1985. (6) McConnell, E.E.; Moore, J. A. Ann. N.Y. Acad. Sci. 1979, 320, 138. (7) “PolychlorinatedDibenzo-p-dioxins”;Report NRCC 18576; National Research Council of Canada, 1981. (8) Patterson, D. G.; Holler, J. S.; Groce, D. F.; Alexander, L. R.; Lapeza, C. R.; O’Connor, R. C.; Liddle, J. A. Enuiron. Toxicol. Chem. 1986,5(4), 355-360.
Received for review September 18,1985. Accepted February 18, 1986. Use of trade names is for identification only and does not constitute endorsement by the U S . Public Health Service or by the U.S. Department of Health and H u m a n Services.
Methylthio Metabolites of Polychlorobiphenyls Identified in Sediment Samples from Two Lakes in Switzerland Hans-Rudolf Buser” and Markus D. Mulier Swiss Federal Research Station, CH-8820 Wadenswil, Switzerland
Methylthio metabolites of polychlorobiphenyls (MeSPCBs) were identified in dated sediment samples from two lakes in Switzerland by using high-resolution gas chromatography (HRGC) and negative ion chemical ionization mass spectrometry (NICI-MS). MeS-PCBs and concomitant PCBs were found in all samples since the 1940s. This onset is earlier than that of other chlorinated pollutants including polychlorinated dioxins and furans and consistent with the first use of PCBs in the 1930s. The results indicate early environmental contamination from these important industrial chemicals. Complex mixtures of MeS-PCBs with various tri- to heptachlorinated congeners were observed. Total concentrations of MeS-PCBs were estimated to be as high as 1-5 ppb (dry weight basis) or up to 2% relative to the concentration of PCBs. MeSPCBs interfere in PCDD analyses and mimic the presence of certain PCDDs in environmental samples. W
Introduction Polychlororobiphenyls (PCBs) are important technical products. They were technically produced first in 1929 and used in a variety of applications. Cumulative production and use up to 1975 were estimated at 635 000 tons for the U.S.and at more than 1 OOOOOO tons worldwide (1). The technical products are complex mixtures of various chloro homologues and isomers. Theoretically, 209 PCB isomers (mono- to decachlorinated) exist, and around 150 have been detected in various technical formulations. Aroclor 1254 and 1260, two common technical products, consist of tri- to heptachlorinated and penta- to nonachlorinated congeners, respectively. Polychloroterphenyls (PCTs) are another related group of compounds produced since the 1930s with a more limited use for similar applications. PCBs are now environmental contaminants on a global scale; they are found nowadays in specimens from such remote areas as the Arctica and Antarctica (2, 3). PCB pollution can be either direct (spills, dumps, accidents, and waste streams) or indirect via atmospheric transport. PCBs can also be combustion-generated ( 4 ) ; however, major pollution of the environment is by the technical products. The later conclusion is based on the fact that 730
Environ. Sci. Technol., Vol. 20, No. 7, 1986
similar PCB isomer compositions are observed in environmental samples as in the technical products, and that environmental levels of PCBs are orders of magnitude higher than that of other combustion-generated compounds (like the polychlorinated dibenzo-p-dioxins, PCDDs, and dibenzofurans, PCDFs) present in emissions from combustion sources at similar concentrations. PCBs are chemically and biologically stable compounds that accumulate in food chains (5). Their environmental fate therefore is important. PCB metabolites have been detected in various substrates and biosystems; metabolites detected were mainly phenolic products (chlorinated hydroxy- and polyhydroxybiphenylsand their methyl ether compounds) and ring-degradedmicrobial oxidation products (benzoic acids) (5,6). Sulfur-containing metabolites (methylsulfonyls, methyl sulfones, and methylthio compounds) have been identified in mammals (mice, rats, guinea pigs, and seal) (7-9) and humans (IO),but not in fish (11). Photolytic dehalogenation of PCBs has been reported and may be of importance for the environmental degradation of PCBs (12). Comparatively less is known about environmental metabolites of PCBs in soil and sediments. Aquatic sediments are the ultimate sink for many anthropogenic compounds. Such sediments can preserve a historical record of their deposition. Analysis of suitably dated sediment cores may thus reveal the historical record of such contaminants, as has been shown for PCDDs and PCDFs in sediments from various lakes (13, 14). In this study, we report the identification of methylthio-substituted PCBs (MeS-PCBs) in dated sediment samples from two lakes in Switzerland. High-resolution gas chromatography (HRGC) and negative ion chemical ionization mass spectrometry (NICI-MS) revealed the presence of these metabolites and concomitant PCBs since the 1940s. To our knowledge, this is the first finding of environmentalmetabolites from these important industrial chemicals. Additional anthropogenic compounds, including PCDDs and PCDFs, were detected in more recent samples from the same locations. The results confirm qualitatively earlier data for PCDDs and PCDFs in sediments from the same lakes (14). The interference of MeS-PCBs in ultratrace (parts per trillion, ppt) environ-
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0 1986 American Chemical Society
