001
Anal. Chem. 1905, 57,801-805 (22) Dreishbach, R. R. “Physical Propertles of Chemical Compounds”; American Chemical Society: Washington, DC, 1959; Vol. 11. (23) Vogel, G. L.; Hamzavl-Abdel, M. A,; Martire, D. E. J . Chem. Thermodyn. 1983, 15, 739-745. (24) Rohrschneider,L. Anal. Chem. 1973, 4 5 , 1241-1247. (25) Davolio, F.; Pedrosa, G. C.; Katz, M. J . Chem. Eng. Data 1981, 26, 26-27. (26) Thomas, E. R.; Eckart, C. A,, Ind. Eng. Chem. Process Des. Dev. 1984, 23, 194-209. (27) Tucker, E. E.; Lane, E. H.; Christian, S.D. J . Soh. Chem. 1981, 10, 1-20. (28) Hussam, A,; Carr, P. W., submitted for publication. (29) Fritz, D. W.; Carr, P. W.,unpublished results. (30) Fredenslund, A.; Jones, R. L.; Prausnltz, J. M. AIChE J . 1975, 21, 1086. (31) Kolb, B. J . Chromatogr. 1975, 112, 287-295.
(32) Shaw, D. A.; Anderson, T. F. Ind. Eng. Chem. Fundam. 1983, 22, 79-83. (33) Eckert, C. A.; Newman, B. A.; Nlcolaides, G. L.; Long, T. C. AIChE J . 1981, 27, 33-40. (34) Loblen, G. M.;Prausnltz, J. M. Ind. Eng. Chem. Fundam. 1982, 21, 109-1 13. (35) Van Laar, J . J . 2.fhys. Chem. 1910, 72, 723. (36) Wilson, G. M. J . Am. Chem. SOC. 1964, 8 6 , 127. (37) Abrams, D. S.; Prausnitz, J . M. A I C h E J . 1975, 21, 116.
RECEIVED for review October 29, 1984. Accepted December 17,1984. This work was supported in part by grants from the University of Minnesota Graduate School and the National Science Foundation.
Determination of Chlorinated Benzenes in Bottom Sediment Samples by WCOT Column Gas Chromatography F. I. Onuska* and K. A. Terry National Water Research Institute, Canada Centre for Inland Waters, Burlington, Ontario, Canada L7R 4A6
An Integrated analytical procedure for determinlng chlorlnated benzene contamlnants that enables quantltatlon of lndlvldual Isomers as low as 0.4 pg/kg in sediment samples has been developed. Preparatlon of the sample can be performed by uslng one of three technlques, namely, Soxhlet extractlon and ultrasonic extractlon or steam dlstlliation. Chlorinated benrenes are then characterized and quantlfled by open tubular column gas chromatography with electron capture detection. Recoverles of Individual Chlorinated benzene Isomers at three dMferent levels from two different types of sediment, one low and one high in organic matter, were evaluated. Although ail three methods are quantltatlve, the steam distiliatlon method was found to be the most efficient for the determlnation, Insofar as time and simpilcity are concerned. Data presented lndlcate that detection iimlts of thls method are 0.4 to 10 pg/kg of individual chlorobenzene Isomers. Chlorobenzene recovery from bottom sediment samples at concentration levels between 1 and 100 pg/kg is 86 f 14%.
T h e occurrence of chlorinated benzenes in environmental systems has created concern about environmental chemicals, regarding the fate and transport of these contaminants in air ( I ) , natural waters ( 2 ) , and sediments (3). Chlorinated benzenes have been used as raw materials and intermediates in the manufacture of pesticides and chlorinated phenols and as process solvents. They are produced in amounts in excess of 500 metric tons annually in the United States (I). Information on their toxicity (4) and metabolic studies of individual isomers after ingestion or exposure are also well documented
(4-6). Chau and Babjak have reported a n ultrasonic extraction technique which in our hands did not provide consistent recoveries for chlorinated benzenes (7). Oliver reports a Soxhlet extraction procedure which is quite time-consuming (8). This paper describes improved analytical methodology for quantitative determination of all the chlorinated benzene isomers in sediment samples. The main objective was to evaluate the efficiency of the exhaustive steam distillation method (9) vs. Soxhlet and ultrasonic extraction followed by centrifugation.
-
Table I. Standard Mixtures Used for Quantitation isomer 1,3-dichlorobenzene 1,4-dichlorobenzene 1,2-dichlorobenzene 1,3,5-trichlorobenzene 1,2,4-trichlorobenzene 1,2,3-trichlorobenzene 1,2,3,5-tetrachlorobenzene 1,2,4,5-tetrachlorobenzene 1,2,3,4-tetrachlorobenzene pentachlorobenzene hexachlorobenzene hexachlorethane hexachlorobutadiene
mixture 1, pg/!JL
mixture 2,
100
25
100 100 10
25
10
5 5 5 5 5 5 10 1 5
10 10 10
10 10
10
PdWL
25 5
Both blank and environmentally contaminated sediments were investigated to study recoveries. The efficiency of the extraction techniques for recoveries was determined by using open tubular column (WCOT) gas chromatography and electron capture detection (ECD). All chlorinated benzenes can be detected in bottom sediment samples at low microgram-to-kilogram levels. Before applying this methodology to bottom sediment samples, the methods were validated for accuracy, precision, and minimum detection limits for individual chlorinated benzene isomers.
EXPERIMENTAL SECTION Reagents. Pesticide quality n-hexane, benzene, acetone, diethyl ether, and 2,2,4-trimethylpentane was used. Two high purity chlorinated benzene standard solutions were prepared from pure individual isomers obtained from RFR Corp., Hope, RI. The specific isomers and their concentration in these solutions are given in Table I. It should be noted that the concentrations of dichlorobenzenes are 5 to 10 times higher than the remaining higher chlorinated isomers. Copper was activated by washing Cu powder in 6 N HC1 for 15 min and storing under n-hexane. Mercury was triple distilled. Sediment Samples. Wet sediment (approximately 5000 g) taken from Lake Superior (Isle Royale, Blake Pt.) was spread
0003-2700/85/0357-0801$01.50/00 1985 American Chemical Society
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ANALYTICAL CHEMISTRY, VOL. 57, NO. 4, APRIL 1985
$14/24
PRE-WASHED
traction thimble. A 10 g equivalent of sediment was placed over the Celite. A 300 mL volume of n-hexane-acetone (1:l) plus 50 mL of 2,2,4-trimethylpentane (isooctane) and some boiling chips were added to the round-bottom flask. Extraction was carried out continuously for 18 h. This time was selected experimentally, because it provided 100% recovery for hexachlorobenzene. After cooling, the extract was transferred with 2 X 25 mL n-hexane rinsings to a 1000-mL separatory funnel. One hundred milliliters of organic-free water was added and the separatory funnel was shaken lightly. The aqueous layer was transferred to a 500-mL separatory funnel and extracted with 100 mL of benzene. If an emulsion was formed, 10 mL of saturated sodium sulfate solution was added. The organic layers were combined, and the aqueous layer was discarded. The organic layer was dried over 5 cm of anhydrous Na2S04in a suction filtration funnel. The 1000-mL separatory funnel was rinsed two times with 25 mL of n-hexane and the extract was passed through the anhydrous Na2S04. The sodium sulfate was rinsed with two 25-mL portions of n-hexane and the sample was then evaporated on the rotary evaporator to 5 mL for further Florisil column chromatography cleanup. The standard Florisil column cleanup procedure was used for Soxhlet extracted samples. Since the samples were analyzed solely for chlorinated benzenes, only the 200 mL of n-hexane eluate was collected and concentrated in a rotary evaporator. Isooctane (10 mL) was added as a keeper before the preconcentration step by rotary evaporation in each extraction method. In addition to the Florisil cleanup, it was necessary to treat the extract for removal of sulfur, if interferences occurred. This was done by shaking it with mercury until newly added mercury no longer dulled (11). For less contaminated samples activated copper should be used. The treated eluates were analyzed by WCOT column gas chromatography and electron capture detector (ECD). (2) Ultrasonic Extraction. A 10-g dry weight equivalent of sediment was placed in a 200-mL centrifuge bottle. Approximately 160 mL of n-hexane-acetone (1:l) was added to the sample. The bottle was then placed into an ice bath on an adjustable stand. The purpose of the ice was to minimize losses by volatilization. In areas where the sediment was badly contaminated with sulfur, the use of mercury was necessary and was added to the final organic extract. The sample was then sonified for 3 min a t 50% duty cycle and output 5, with the mouth of the bottle butted up against the base of the horn. After this time, the horn was rinsed with 2 mL of hexane-acetone into the extract. The bottle was then capped and centrifuged at 2000 rpm at 10 "C for 3 min. The solution was then decanted into a 1000-mL separatory funnel where 100 mL of organic-free water was added to the combined extracts and shaken for 1min with venting at 20-s intervals. The aqueous portion was drained into a secondary separatory funnel (500 mL capacity) and extracted with two 60-mL portions of benzene. The combined organic extracts were dried through a 5-cm column of anhydrous Na2S04in an Alihn filter into a 500-mL round-bottom flask. Vacuum was applied only after all of the solvent had apparently passed through. The sample was concentrated to 5 mL of isooctane by rotary evaporation a t 35-40 "C under aspirator vacuum. (3) Steam Distillation. An equivalent of 10 g of dry sediment was weighed and quantitatively transferred into a 1000-mL round-bottom flask with 250 mL of organic-free water. Approximately 10 mL of water was added into the condenser followed by 10 mL of n-hexane. One gram of Tenax was placed into a Pasteur pipet secured by glass wool which was then joined to the flask on the top of the condenser as shown in Figure 1. An asbestos jacket connected to a Variac transformer was placed around the flask and the water was boiled for 3 h. The condenser was cooled by water at 1L/min to condense the steam containing the volatile organics. After 3 h, the hexane was drained out from the withdrawal tube by opening the stopcock. The n-hexane was dried through sodium sulfate. The Tenax column was washed with 10 mL of n-hexane and was combined with the dried n-hexane from the condenser. This volume was made up to 10 mL with isooctane. No cleanup or Florisil was required, but if sulfur contamination was evident, mercury was added to the extract. Gas Chromatographic Analyses. All GC/ECD analyses were performed with a Varian Vista 6000 gas chromatograph equipped with the splitless injector as described earlier (12). We used open
-FL
1
II DISPOSABLE JPIPETTE
NIELSON - KRYGER DISTILLATION APPARATUS
Figure 1. Nielson-Kryger steam distillation apparatus with an adsorption adaptor. evenly in a large shallow glass dish and allowed to air-dry a t room temperature in a contaminant-free area. The sample was stirred and mixed occassionally during drying to break it into small pieces. This process was continued until the sample appeared visually dry and free flowing. The dried sample was then manually ground to a fine powder with a mortar and pestle. This homogenized sample was used as a blank because it contained no chlorobenzenes as was determined by the analysis. Two environmentally contaminated sediments were used: Hamilton Harbour (74.6% water) and an EC-2 sediment sample. The EC-2 sample was a mixture of the Hamilton Bay sediment and a Lake Ontario sediment was used as a standard reference (2). Spiking Procedure. Ten grams of blank sediment was added to the extraction vessel; 10 mL of organic-free water was added to wet the sample. The appropriate spike was then added and the sample swirled to mix it as evenly as possible. The vessel was then sealed and allowed to equilibrate for 10 h. Similarly, 10 g of wet sediment from Hamilton Harbour was weighed into the extraction vessel and 10 mL of organic-free water was added. The spike was then introduced over the sample in a manner described elsewhere (10). Equilibration time was 10 h. Apparatus. Soxhlet Extractor. The apparatus includes a 500-mL round-bottom flask, heating mantle with variable voltage control, Soxhlet extractor (100-mL capacity), and a Liebig water-cooled condenser. SonifierlCell Disruptor. The apparatus, from Ultrasonics Inc., Model W-350, includes the following: power supply, 120 V, 5 A, 60 Hz, output power 350 W to the converter, frequency of 20 kHz, continuous and intermittent duty cycle; converter with 95% efficiency in converting electrical energy to mechanical vibrations (20 cm long x 62.5 mm diameter); Sonabox enclosure for decreasing cavitation sound; horn, standard distruptor horn of titanium alloy (17.5 cm long X 19 mm diameter) and high gain disruptor horn (6.25 cm X 19 mm diameter); cooling bath, ground ice in a 1-L beaker; centrifuge, 2000 rpm a t 10 "C by Internation Refrigerated, Model PR-6, or equivalent. Steam Distillation Apparatus. A Nielson-Kryger distillation apparatus available from ACE Glass Co., Vineland, NJ, was used with a Tenax trap made from a disposable pipet with silanized glass wool plug and approximately 1 g of 80/100 mesh Tenax followed by another short silanized glass wool plug as shown in Figure 1. Extraction of Sediments. ( I ) Soxhlet Extraction Method. A 25-mm layer of solvent extracted Celite was placed in an ex-
ANALYTICAL CHEMISTRY, VOL. 57, NO. 4, APRIL 1985 I
Table 11. Retention Times, Relative Retention Times, and Response Factors for Chlorinated Benzenes on Carbowax 20M WCOT Columnn chlorobenzene isomer
803
response retention re1 retention concn, factor, time, min time pg/pL counts/pg
1,3-dihexachloroethane 1,4-di1,2-dihexachlorobutadiene 1,3,5-tri1,2,4-tri1,2,3-tri1,2,3,5-tetra1,2,4,5-tetra1,2,3,4-tetrapentachlorobenzene hexaachlorobenzene
5.90 6.21 6.52 7.42 7.82
0.227 0.239 0.251 0.286 0.301
25 1 25 25 5
280 690 155 135 355
8.06 11.17 13.29 14.72 15.02 18.28 20.82 25.97
0.310 0.430 0.512 0.567 0.578 0.704 0.802 1.000
5 5
1010 1070 1205 1690 1440 1650 1965 1900
5 5 5 5 5 10
" Column and conditions described in the text earlier using Hewlett-Packard instrument. Table 111. Replicate Analyses of Chlorinated Benzenes in EC-2 Sediment, Sample Extracts and Their Minimum Detection Limits" chlorobenzene
amt found, pg/rL
1,3-dihexachlorobutadiene 1,3,5-tri1,2,4-tri1,2,3-tri1,2,3,5-tetra1,2,4,5-tetra1,2,3,4-tetrapentahexatotal
4.7 f 0.1 20.6 f 0.3 7.1 f 0.1 12.3 f 0.1 0.9 f 0.1 1.7 f 0.1 23.8 0.2 13.7 f 0.2 20.9 f 0.2 93.8 f 0.3 199.5 f 1.7
MDL, a / k g 1.5 0.7 1.0 0.8 0.8 0.5 0.5 0.5 0.4 0.4
*
Figure 2. Separation of chlorinated benzenes on the Carbowax 20M WCOT column (50 m X 0.25 mm i.d.): column at 75 OC for 2 rnin programmed at 4 'C/mln to 180 OC and held at final temperature for 5 min; attenuator at 64X.
WCOT column chromatographic peaks were identified by using a method of relative retention time matching (RRT). This also allowed summing selected peak areas assignable to the homologues of chlorinated benzenes similar to the method reported for the quantitation of PCBs (13).
"Data were calculated from four replicate samples using cool on-column injection. tubular column chromatography and 50 m X 0.25 mm i.d. Carbowax 20M coated on fused silica capillary (df = 0.2 wm) having 207 000 effective plates for hexachlorobenzene as k' = 21.7. Hydrogen was used as a carrier gas with a linear velocity of 65 cm/s. An initial temperature of 75 O C was held for 2 min followed by temperature programming to 180 O C a t 4 "C/min. The final temperature was held for 5 min. The injector temperature was 200 "C, the detector temperature was 350 O C , and the flow rate of 3.2 mL/min was employed to sweep the septum. The detector makeup gas was nitrogen a t 30 mL/min. Splitless time was 35 9.
Quantitation a n d Data Collection. Data were reported on a Spectra Physics reporting integrator, Model SP-4100. The
RESULTS AND DISCUSSION A gas chromatogram of the chlorinated benzene standards is shown in Figure 2. All isomers are separated on the Carbowax 20M WCOT column. The retention times, the relative retention times and an appropriate response factor for the particular isomers are given in Table 11. The response factors were not found to vary widely when hydrogen was used as a carrier gas in contrast to data reported by Oliver et al. (2). Detector response is linear over 3 orders of magnitude. A chromatogram showing an EC-2 sample extract is given in Figure 3 and quantitative results are provided in Table 111. The minimum detection limit (MDL) for chlorinated benzenes at 3:l SIN and attenuation of 32X corresponds t o approximately 15 pg for dichlorobenzenes and approximately between 0.4 and 1.0 pg for the remaining chlorinated benzenes. Calculated minimum detection values (MDL) are given in Table 111.
Table IV. Recoveries of Chlorinated Benzenes from Lake Superior Sediment Using Soxhlet Extraction chlorinated benzene isomers 1,3-&ichlorobenzene 1,4-dichlorobenzene 1,Z-dichlorobenzene 1,3,5-trichlorobenzene 1,2,4-trichlorobenzene 1,2,3-trichlorobenzene 1,2,3,5-tetrachlorobenzene 1,2,4,5-tetrachlorobenzene 1,2,3,4-tetrachlorobenzene
pentachlorobenzene hexachlorobenzene
spiked concn,
recovery,
RSD,
wg/g
%
%
1000
55.4 53.9 54.1 67:s 69.7 72.0 69.9 69.4
1000 1000 100 100 100
100 100
100 100 100
71.7
73.3 78.2
0.3 0.7
0.6 15.8 13.6 14.2
9.8 12.2
10.1 9.0 8.9
spiked concn, pg/g
recovery,
RSD,
spiked concn,
recovery,
RSD,
%
%
wg/g
%
70
,100 100 100
48.1
1.2
10
50.2
1.2
10
54.0 68.0 67.0 73.0 73.0 71.0 77.0 79.0 81.0
0.7 10.8 5.3 6.9 11.5
10 1 1 1 1 1 1 1 1
34.5 37.3 49.8 54.0 66.0 43.0 48.0 47.0 46.0 46.0 58.0
10 10 10 10
10 10 10 10
12.2
6.0 3.4 2.9
4.3 1.5 1.6 9.3 12.9 15.6 11.0
12.3 8.7 7.8 1.7
804
ANALYTICAL CHEMISTRY, VOL. 57, NO. 4, APRIL 1985
Table V. Recoveries of Chlorinated Benzenes from Lake Superior Sediment Using Ultrasonic Extraction Method
chlorinated benzene isomers
spiked concn, M/P
recovery,
RSD,
%
%
1000
46.6 44.1 45.2 61.7 62.7 63.8 70.2 71.3 71.5 76.7 88.6
0.1 0.5 0.5
1,3-dichlorobenzene 1,4-dichlorobenzene 1,2-dichlorobenzene 1,3,5-trichlorobenzene 1,2,4-trichlorobenzene 1,2,3-trichlorobenzene 1,2,3,5-tetrachlorobenzene 1,2,4,5-tetrachlorobenzene 1,2,3,4-tetrachlorobenzene pentachlorobenzene hexachlorobenzene
1000
1000 100 100 100 100 100 100 100
100
spiked concn, Pg/g
recovery,
RSD,
RSD,
%
spiked concn, N?/g
recovery,
%
%
%
100 100 100 10 10
50.5 52.9 52.2
0.8
10
0.2 0.6 9.8 6.9 8.4 9.1 6.2 6.2 5.3 3.4
10
18.0 43.0 39.2 32.0 39.0 52.0 35.0 37.0 35.0 41.0 44.0
3.3 4.9 4.0 17.5 13.6 9.2 18.9 13.8 19.1 31.7 11.6
0.5
3.2 3.2 0.8 0.1
71.0
75.0 72.0 78.0 79.0 79.0 80.0 82.0
10
10 10
1.3
10
0.1 3.6
10 10
10 1 1 1 1 1 1 1 1
Table VI. Recoveries of Chlorinated Benzenes from Lake Superior Sediment Using Steam Distillation Method
chlorinated benzene isomers
spiked concn, Pg/g
recovery,
RSD,
%
%
1,3-dichlorobenzene 1,4-dichlorobenzene 1,2-dichlorobenzene 1,3,5-trichlorobenzene 1,2,4-trichlorobenzene 1,2,3-trichlorobenzene 1,2,3,5-tetrachlorobenzene 1,2,4,5-tetrachlorobenzene 1,2,3,4-tetrachlorobenzene pentachlorobenzene hexachlorobenzene
1000 1000 1000 100 100 100 100 100 100 100 100
75.9 80.9 80.6 89.3 89.6 90.5 86.6 93.6 90.8 90.5 87.5
0.6 0.6 0.5 20.8 18.8 14.6 9.8 11.0 8.9 1.0 4.2
spiked concn, kg/g
recovery,
RSD,
RSD,
%
spiked concn, !Jg/g
recovery,
%
%
%
100 100 100 10 10 10 10 10 10 10
71.3 73.2 75.0 75.0 84.0 84.0 82.0 83.0 88.0 80.0 82.0
2.1
10
2.0
10 10
73.8 71.8 76.1 66.0 82.0 79.0 89.0 89.0 84.0 84.0 80.0
1.4 2.3 3.9 17.3 7.8 5.4 10.2 10.4
10
2.2
33.2 2.9 2.9 2.5 1.4 25.4 12.3 7.5
1 1
1 1 1 1 1 1
5.0
9.4 16.6
Table VII. Analysis of Chlorinated Benzenes from Hamilton Harbour Sediment Samples by Soxhlet Extraction, Sonification, and Steam Distillation (n = 3)
isomers
concn found by steam distillation, ng/g dry w t
1,3-dichlorobenzene 1,4-dichlorobenzene 1,3,5-trichlorobenzene 1,2,4-trichlorobenzene 1,2,3-trichlorobenzene 1,2,3,5-tetrachlorobenzene 1,2,4,5-tetrachlorobenzene 1,2,3,4-tetrachlorobenzene pentachlorobenzene hexachlorobenzene
RSD, %
concn found by Soxhlet, ng/g dry wt
RSD, '70
concn found by sonification, ng/g dry wt
RSD, %
31.0 68.6 2.9 13.0
3.6 3.4 13.9
81.4 4.5 20.2
13.0 19.2 21.4
39.4 2.8 5.8
3.6 39.4 6.2
3.0
21.9
4.4
37.1
3.4
3.7
3.8 6.0
15.2 11.7
3.6 7.0
44.9 18.0
5.2
9.5
0.5
Table VIII. Comparison of Spiked Hamilton Harbour Sediment Analysis Using Three Different Techniqueso
steam distillation chlorinated benzene isomers 1,3-dichlorobenzene 1,4-dichlorobenzene 1,2-dichlorobenzene 1,3,5-trichlorobenzene 1,2,4-trichlorobenzene 1,2,3-trichlorobenzene 1,2,3,5-tetrachlorobenzene 1,2,4,5-tetrachlorobenzene 1,2,3,4-tetrachlorobenzene
pentachlorobenzene hexachlorobenzene
Soxhlet extraction
sonification
1
2
%
1
2
%
1
2
%
131.0 168.6 100.0 12.9 23.0
127.0 149.5 88.9 10.6 19.1 8.9
97 89 89 82 83 89 86 88 83 34 90
100.0 181.4
72.7 112.0 66.4
73 62 66 72 76 80 74 76 88 92 82
100.1 139.4
42.9 60.1 45.8 6.3 7.3 6.3 7.5 6.1 6.8 7.4 9.1
43 43 46 49 46 63 56 61 68 74 60
10.0
13.0 10.0
10.0 13.8 16.0
11.2
8.8 8.3 11.6 14.4
100.0
14.5 30.2 10.0 14.4 10.0 10.0 13.6 17.0
10.5
23.0 8.0 10.7 7.6 8.8 12.5 14.0
100.0
12.8 15.8 10.0
13.4 10.0 10.0
10.0 15.2
1, spike + amount found in the sample (ng/g); 2, recovered amount (ng/g); %, percentage of the recovered amount. All samples were spiked with mixture no. 1 (see Table I).
When environmental sediment samples are analyzed for chlorinated benzenes, drying and grinding should be eliminated. A wet sediment sample (15 g) should be weighed for each analysis. Moisture content can be determined on a separate portion of the sample and incorporated into the
calculation for reporting data on a dry weight basis. Data t o define recoveries and accuracy for the Soxhlet extraction, the sonification, and the steam distillation are shown in Tables IV-VI. Three replicate samples and a blank of the prepared dry sediment (10 g each, dry weight) were
ANALYTICAL CHEMISTRY, VOL. 57, NO. 4, APRIL 1985 I
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I
I
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I 1
4
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Flgure 3. Hamilton Harbour sample (EC-2) chromatographed under the identical conditions as Figure 2: (1) 1,3dichlorobenzene; (2) 1,4dichlorobenzene; (3) 1,2dichlorobenzene;(4) hexachlorobutadiene;(5) 1,3,54richlorobenzene;(6) 1,2,4-trichlorobenzene; (7) 1,2,3-trichlorobenzene; (8) 1,2,3,5-tetrachlorobenzene; (9) 1,2,4,54etrachlorobenzene; (10) 1,2,3,4-tetrachIorobenzene;(11) pentachlorobenzene; (12) hexachlorobenzene.
extracted, concentrated, and analyzed according to the previously described procedures. Recoveries of chlorobenzenes from spiked sediment samples averaged 55 f 11% for the Soxhlet extraction, 48 f 12% for the sonification-centrifugation, and 81 f 12% for the steam distillation method. To demonstrate the effectiveness of discussed preconcentration methods and the gas chromatography with open tubular column separation, we determined the concentrations of chlorinated benzenes in Hamilton Harbour bottom sediment samples and the same sample spiked with 10 pg/g of chlorinated benzenes. Results are given in Tables VI1 and VIII. In addition, a study of the recovery of the Hamilton Harbour sediment spiked with 10 pg/g of chlorinated benzenes was carried out by using three methods: Soxhlet extraction,
805
sonification, and steam distillation. Results of these tests show the superiority of the steam distillation procedure over the other extraction procedures as far as bottom sediments are concerned (Table VIII). Steam distillation produced good recoveries after just 3 h of extraction time. The results of this study show this technique to be the most efficient method for recovery of chlorinated benzenes from bottom sediment samples of different matrices and is the method of choice due to its simplicity and time efficiency. Even a t low concentrations, recoveries of chlorinated benzenes were over 82 % . In general, the recoveries obtained are significantly greater than any of the other procedures tested. The Soxhlet extraction procedure provided consistent recoveries a t medium and higher concentrations with recovered amounts in range of 66-92%. The lower efficiency is probably due to the matrix variability. As was observed, the many evaporation and preconcentration steps and solvent changes could also be responsible for lower recoveries. The sonification procedure did not provide quantitative results. The volatile dichloro- and trichlorobenzene isomer quantitation was not reproducible. In conclusion, the steam distillation procedure appears satisfactory for extracting chlorinated benzenes from bottom sediment samples. Extracts can be directly used for determination of chlorinated benzenes by means of WCOT column gas chromatography using a n electron capture detector.
LITERATURE CITED (I) Langhorst, M. L.; Nestrick, T. J. Anal. Chem. 1979, 57,2018-2025. (2) Oliver, B. G.; Bothen, K. D. Anal. Chem. 1980, 52, 2066-2069. (3) Onuska, F. I.; Thomson, R.; Terry, K. CCIW-Internal Report, 13-AMD3-81, Burlington, Ontario, 1981. (4) Rofman, K.; Mueller, W. F.; Coulston, F.; Korte, F. Chemosphere 1878, 7, 177-184. (5) Kohli, J.; Jones, D.; Safe, S. Can. J . Biochem. 1978, 5 4 , 203-208. (6) Morlta, M.; Oishl, S. Bull. Environ. Contam. Toxicol. 1975, 14, 313-318. (7) Chau, A. S.Y.;Babjak, L. J. J . Assoc. Off. Anal. Chem. 1979, 62, 107-113. (8) Oliver, B. G.; Bothen, K. D. Int. J . Environ. Anal. Chem. 1982, 72, 131-139. (9) Veith, G. 0.; Klwus, L. M. Bull. Environ. Contam. Toxlcol. 1977, 1 4 , 631-636. - - . - - -. (10) Bellar, T. A,; Lichtenberg, J. J. ASTM Spec. Tech. Publ. 1975, No. 573. 206-219. .. ., -. . - ..
(1 1) Goerlitz, D. F.; Law, L. M. Bull. Environ. Contam. Toxicol. 1971, 6 , 9-10, (12) Onuska, F. I.; Komlnar, R. J.; Terry, K. J . Chromatogr. Sci. 1983, 27, 5 12-5 18. (13) Onuska, F. I.;Kominar, R. J.; Terry, K. J . Chromatogr. 1983, 279, 111-118.
RECEIVED for review October 26, 1984.
10,1984. Accepted December
