Anal. Chem. 1980, 52, 1492-1496
1492
Table I shows the effect of the organic vapors studied a t the 5% v/v (100 ppm toluene 5 ppm of interferences) level. Since in the real case, where the toluene is being used as a solvent, such as in printing plants, the presence of benzene and other alkylbenzenes is less than 5% v/v, no interference is anticipated as shown in Table I. However, a t the 100% v/v (100 ppm of toluene + 100 ppm of interferences) level these solvents may cause significant interferences. T h e interference from water vapor could be completely eliminated by using Nafion tubing (24, 25). Water is selectively removed by diffusion through a permaselective membrane of Nafion tubing (Du Pont, type 811) without any loss of the sample. As the water vapor is adsorbed and permeates across the walls of the Nafion tubing, it is removed by either a countercurrent flow of dry nitrogen gas sweeping the outer surface of the tubing (24) or using desiccants such as magnesium perchlorate or 13X molecular sieve. For the field portable monitoring device, it is more convenient to use a desiccant for drying the outer surface of Nafion tube as described by Foulger et al. (25). Calibration Curve. The change of frequency, 1F,ranged from 4 Hz for 30 ppm to 110 Hz for 300 ppm and fit the general equation AF = 0.39 [toluene] - 7.0. 1F was taken as the frequency difference between the base line before sampling and the steady state, which occurs when the saturation between toluene vapor a n d the coating substrate is achieved. The relative standard deivation of the detector was about 4%. Lifetime of the Detector. With Carbowax 550 as a coating, t h e detector was tested for the lifetime of operation by comparing the base-line shift and the responses after two months. The base line was shifted due to some loss of coating substrate. However, this loss was only about 0.2 pg or 0.5% of coating substrate calculated from the shift of base line of 80 Hz. T h e signals, AF,observed were 110 and 108 Hz, initially and after two months, respectively, for 300 ppm toluene. T h e coating technique seems to critically effect a shift of the base line, and hence the lifetime of the detector. The coated Carbowax 550 should strongly adhere to the surface of electrodes in order to minimize the loss of coating. We observed
+
that if the crystal was placed on an oven a t 80 "C for 24 h or more after coating, the base line was more stable. This may be due to an increased adhesion of coating on the electrode.
LITERATURE CITED Pitts, J. N., Jr.; Winer, A. M.; Darnell. K. R . ; Lloyd, A. C.; Doyl, G. J. "Hydrocarbon Reactivity and the Role of Hydrocarbons, Oxides of Nitrogen, and Aged Smog in the Production of Photochemical Oxidants", International Conference on Photochemical Oxidant Pollution and Its Control, Proceedings, Vol. 11. EPA - 600/3-77-001b, Jan. 1977. Cohr, K. H.; Stokholm, J. S c a d . J . Work. Environ. Heatth 1979, 5 , 71. NIOSH Manual of Analytical Methods, "Organic Solvents in Air", P & CAM 127, DHEW, NIOSH Publication number 77-157-A, 1977. Grizzle, P. L.; Coleman, H. J. Anal. Chem. 1979, 51, 602. Hester, N. E.; Meyer, R. A. Environ. Sci. Techno/. 1979, 73, 107. Hlavay, J.; Guilbault, G. G. Anal. Chem. 1977, 49, 1890. Scheide, E. P.; Warner, R . 0 . J. Am. Ind. Hyg. Assoc., J . 1978, 3 9 , 745. King. W. H. Jr.; Environ. Sci. Technol. 1970. 4 , 1136. Frechette, M. W.; Fasching, J. L. Environ. Sci. Techno/. 1973, 7 , 1135. Karasek. F. W.; Gibbins, K. R. J , Chromatogr. Sci. 1971, 9 , 535. Karasek. F. W.; Guy, P.; Hill, H. H.; Tiernay. J. M. J . Chromatogr. 1976, 724, 179. Karasek. F. W.; Tiernay, J. M. J . Chromatogr. 1974, 89, 31. Karmarkar, K . H.; Guilbault. G. G. Anal. Chim. Acta 1974, 77,419. Scheide, E. P.; Guilbault, G. G. Anal. Chem. 1972, 44, 1764. Karmarkar, K. H.; Webber, L. M.; Guilbault, G. G. Environ. Lett. 1975, 8 , 345. Karmarkar, K. H.; Guilbault. G. G. Anal. Chim. Acta 1975, 75, 111. Hlavay, J.; Guilbault, G. G. A n d . Chem. 1978, 50, 1044. Hlavay, J.; Guilbault, G. G. Anal. Chem. 1978, 50, 965. Webber, L. M.; Kamarkar, K. H., Guilbautt, G. G. Anal. Chim. Acta 1978, 9 7 , 29. Tomita, Y . ; Ho, M. H.; Guilbault, G. G. Anal. Chem. 1979, 57, 1475. King, W. H.. Jr.; Anal. Chem. 1964, 3 6 , 1735. Miguel, A. H.; Natusch, D. F. S. Anal. Chem. 1975, 47, 1705. Calibration Standards, Analytical Instrument Development, Inc.. Avondale, Pa. Simmonds, P. G.; Kerns, E. J . Chromatogr. 1979, 186, 785. Foulger, 6 . E.; Simmonds, P. G. Anal. Chem. 1979, 57, 1089.
RECEIVED for review March 7,1980. Accepted April 30,1980. This work was conducted with the financial assistance of the Army Research Office (Grand number DAAG29-77-GO226) and a travel grant from the North American Treaty Organization (Grant Number NATORG 1719) which permitted a joint research effort between United States and Danish Laboratories.
Ultrasonic Extraction of Polychlorinated Dibenzo-p-dioxins and Other Organic Compounds from Fly Ash from Municipal Incinerators G. A. Eiceman, A. C. Viau, and F. W. Karasek" Guelph- Waterloo Centre for Graduate Work in Chemistry, Waterloo Campus, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
Polychlorinated dibenzo-p-dioxins (PCDDs) and other organic compounds are solvent extracted from 10- to 20-9 samples of fly ash from municipal incinerators with 200 mL of benzene using ultrasonic agitation for 1 h. A convenient filtering device is used to separate fly ash and solvent which is then concentrated to 100 pL using a rotary evaporator. Extracts are analyzed directly by gas chromatography/mass spectrometry, including selected Ion monitoring for PCDDs. Results from five replicate analyses of a fly ash sample yielded averages and standard deviations (ng/g) for the tetra- to octachlorinated dibenzo-p-dioxins of 8.6 f 2.2, 15.0 f 4.0, 13.0 f 3.4, 3.2 f 1.0, and 0.4 f 0.1, respectively. 0003-2700/80/0352-1492$01 O O / O
Fly ash which is produced during the incineration of municipal wastes is 7 5 to 90% inorganic matter but may also contain a complex mixture of extractable organic compounds. Approximately 100 organic compounds have been identified by gas chromatography/mass spectrometry (GC/MS) in benzene extracts of some fly ash samples. These compounds include polycyclic aromatic hydrocarbons (PAHs) and numerous chlorinated compounds which include polychlorinated phenols, polychlorinated benzenes, polychlorinated dibenzofurans (PCDFs), and polychlorinated dibenzo-p-dioxins (PCDDs) (I). Polychlorinated dibenzo-p-dioxins are a series of tricyclic C 1980 American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 52, NO. 9, AUGUST 1980
aromatic compounds which are substituted with one to eight chlorine atoms leading to the formation of 75 possible isomers. Some of these isomers pose a severe health threat t o human and animal life. In several instances, adverse biological effects have been associated with exposure t o isomers of PCDDs; known incidents include the outbreaks of chicken edema disease ( Z ) , severe poisoning from cooking oil in Yusho, Japan ( 3 ) ,environmental devastation at Sevesco, Italy ( 4 ) ,outbreaks of chloracne in industrial workers (53,and increased levels of birth malformations in humans exposed t o herbicides containing chlorinated dioxins (6). Certain isomers are known t o cause induction of the enzymes aryl hydrocarbon hydroxylase and 6-aminolevulinic acid synthetase (2, 7 ) and are toxic ( 8 ) ,mutagenic ( 9 ) , and teratogenic ( I O ) . Chlorinated dioxins are particularly stable in the environment and have been found distributed in soil, fish, and mammals in regions where PCDDs had been released (11). Polychlorinated dibenzo-p-dioxins have also been detected in fly ash from municipal incinerators located in T h e Netherlands, Japan, Canada, and France, although relative concentrations of specific isomers and total concentration levels were different (I). T h e use of large-scale, urban-based incinerators as a method for disposal of municipal refuse is expected t o increase, and the release of airborne particulates and fly ash containing toxic organic compounds including PCDDs from these incinerators may constitute a n unrecognized, potent threat t o human health. Routine monitoring of PCDDs and other harmful organic compounds in fly ash and airborne particulates from municipal incinerators and other combustion sources would be facilitated by a rapid, convenient, inexpensive, and reproducible extraction technique. T h e Soxhlet apparatus has been widely a n d successfully applied in the extraction of organic compounds from airborne particulates ( I 2 ) ,coke oven emissions (131, soil samples (14), and incinerator fly ash ( I , 1 5 ) , b u t the Soxhlet apparatus has certain limitations for use in routine or survey analyses. These disadvantages include considerable sample and solvent handling, lengthy extraction times, careful cleaning and handling of expensive, fragile glassware, and bulky accessory apparatus. Such restrictions limit the efficiency of the extraction step in analysis procedures. Solvent extraction using ultrasonic agitation (ultrasonic extraction) is an alternate extraction technique which has been applied t o extracting organic compounds in airborne particulates (16) and reported recovery efficiencies using ultrasonic extraction were equal t o or better than most efficiencies using Soxhlet extraction (17). This paper examines ultrasonic extraction of municipal incinerator fly ash for organic compounds including the polychlorinated dibenzo-p-dioxins. Reproducibility of ultrasonic extraction was determined by selected ion monitoring analyses of benzene extracts for PCDDs in five replicate fly ash samples and by using a convenient filtering device which is suitable for measurement of organic compounds a t trace concentration levels.
EXPERIMENTAL Sample Collection a n d Storage. Grab samples were drawn from municipal incinerators equipped with electrostatic precipitators and located in major urban centers in Ontario. These samples were characterized earlier in a survey study which used the Soxhlet extraction technique with 200 mL of benzene for 16 h ( I ) . Results from that study showed Ontario 1 (01)and Ontario 2 ( 0 2 ) contained similar components; however 01 contained higher concentrations of PCDDs and chlorinated benzenes while 0 2 contained higher concentrations of PAHs and n-hydrocarbons. Samples were provided by Andre Foldes of the Ontario Ministry of the Environment. Fly ash samples were shipped and stored in closed glass containers at ambient temperatures and were protected from visible and ultraviolet light.
1493
Sample Extraction. All glassware, sample vials, and Pasteur pipets used in the extraction and concentration procedures were cleaned using the following procedure; ultrasonic agitation for 15 min in a 2% (approximate) aqueous solution of Alconox detergent (Alconox, Inc., New York, N.Y.), rinsing with copious amounts of tap water, thorough rinsing with deionized water, and heating in a general laboratory oven for 1 h at 350 "C'. All sample transfers were performed using Pasteur pipets and every Pasteur pipet was rinsed three times with 2-mL portions of benzene just prior to use. Approximately 10- to 20-g samples of fly ash were extracted in a 300-mL round bottom flask (extraction flask) by adding 100 mL of benzene ("distilled in glass" grade, Burdick and Jackson, Muskegon, Mich.) to loose fly ash, capping the flask with a ground-glass stopper, and ultrasonically agitating the mixture for 60 min with a 200-W ultrasonic bath (Branson Ultrasonic Canada, Scarborough, Ontario) containing tap water at room temperature. Following the ultrasonic agitation step, benzene was decanted from a 300-mL extraction flask to filtering apparatus, which is illustrated in Figure 1 and described below. Fly ash which was carried over during decanting was retained in the modified sintered-glass crucible while the benzene extract was collected in the 300-mL flat-bottom boiling flask. Residual fly ash in the extraction flask was washed successively with two 25-mL aliquots of fresh benzene solvent and rinsings were also decanted to the filtering apparatus where benzene rinses were composited with the initial extract in the flat-bottom flask. The filtering apparatus was disassembled, the flat-bottom flask was directly attached to a rotary evaporator, and extracts were reduced in volume to 500 FL at approximately 60 "C under aspirator vacuum. Concentrates were transferred to 1.0-mL Reacti-Vials (Pierce Chemical Co., Rockford Ill.) with two 0.1-mL rinsings of fresh benzene. A gentle stream of nitrogen (Linde 99.995%) directed over the mouth of the Reacti-Vial was used t o adjust the final volume to 50 FL. Samples were stored in a refrigerator at 1 to 5 "C until they were analyzed by GC/MS. Proceduw blanks were prepared using fresh benzene by repeating the entire extraction and concentration procedure without a fly ash sample. Recovery Reproducibility. The reproducibility of recovery for the ultrasonic extraction method was measured by determining PCDD levels in five replicate fly ash samples. Samples of Ontario 1 were extracted with benzene and the concentrates were directly analyzed by GC/MS using selected ion monitoring for the tetrathrough octachlorinated dibenzo-p-dioxins. Weights for the replicates were 9.9, 9.9, 10.0, 10.1, and 10.0 g. Extraction Selectivity Study. A composite sample was prepared from the two previously analyzed samples so a single mixture would contain PAHs, PCDDs, polychlorinated benzenes, and other organic compounds at similar concentration levels. The mixture was prepared by blending 110 I: of Ontario 1 (01)and 60 g of Ontario 2 ( 0 2 ) , and 22.4 g of this mixture was used in the extraction. The benzene concentrate was analyzed by GC/MS using Dual-Mode to generate a total ion chromatogram and six mass chromagrams. Ions which were monitored and corresponding compounds were: m / e 57.1, n-hydrocarbons; m l e 74.1, methyl esters; m / e 163.1, dimethyl phthalate; mil? 149.1,phthalate esters; m / e 202.1, pyrene, fluoranthene; and m / e 252.1, pentachlorobenzene. Analysis by Gas Chromatography/Mass Spectrometry (GC/MS). A Hewlett-Packard 5992A GC'/MS/Calculator system equipped with single floppy disk, x-y plotter, and 2 m x 2 mm i.d. glass column was used for GC/MS analysis. The chromatographic column was filled with Aue Packing, a high performance packing of 0.2% w / w layer of Carbowax 20M on an exhaustively acid washed 100/120 mesh Chromosorb W (28). Chromatographic conditions were: initial temperature, 90 "C; program rate, 4 "C; final temperature, 250 "C; time a t final temperature, 15 min; injection port temperature, 250 "C; and helium carrier gas flow, 40 mL/min; measured at 90 " C oven temperature. Two GC/MS techniques were used: Dual-Mode and Selected Ion Monitoring (SIM). In Dual-Mode analysis, mass spectra were continuously scanned at a rate of 330 atomic mass units/s from m l e 500 to m / e 40. Spectra saved and stored on the flexible disk were those taken at the GC maxima. The spectrum of lowest abundance between consecutively saved spectra was also saved as background and at the conclusion of a Dual-Mode run, each
ANALYTICAL CHEMISTRY, VOL. 52, NO. 9, AUGUST 1980
1494
Table I. Estimated Concentrations (nglg) of PCDDs in Fly Ash from Municipal Incinerators Replicate Number chlorine substitution
peak no.
1
2
3
4
5
average
std. dev.
rel. std. dev., %
4
1 2 3 4 sum
1.3 1.3 2.4 2.1 7.1
2. a 2.0 3.7 3.2 11.0
1.3 1.3 3.6 2.1 7.0
2.1 2.1 2.3 3.1 11.0
1.2 1.2 2.3 2.0 6.7
1.6 1.6 2.9 2.5 8.6
0.46 0.43 0.72 0.60 2.2
29 27 25 24 26
5
1 2 3 4
5.2 4.7 4.7 5.6 20.0
3.0 2.8 2.8 3.4 12.0
4.9 4.4 4.4 5.4 19.0
3.0 2.7 2.7 3.4 12.0
3.9 3.5 3.5 4.3 15.0
1.1 0.95 0.94 1.1 4.0
28 27 21 26 27
2.6 3.7 2.9 2.1 11.0
4.1 5.6 4.4 3.0 17.0
2.3 3.2 2.6 1.7 9.8
3.2 4.4 3.5 2.4 13.0
0.89 1.2 0.87 0.58 3.4
28 27 25 24 26
sum
3.3 3.0 3.1 3.8 53.0
6
1 2 3 4 sum
2.8 3.9 3.0 2.2 12.0
4.2 5.7 4.4 3.0 17.0
7
1 2 sum
1.1 1.7 2.8
1.7 2.6 4.3
0.93 1.5 2.4
1.6 2.5 4.1
0.94 1.4 2.3
1.1 1.9 3.2
0.34 0.57 0.95
31 30 30
8
1
0.35
0.53
0.28
0.51
0.32
0.40
0.11
28
background spectrum was subtracted from its corresponding component spectrum. The software used in the Dual-Mode runs was supplied by the manufacturer and modified by the procedure of Dickson (19) to allow six mass chromatograms and total ion chromatograms to be stored on flexible disk in addition t o individual mass spectra. Analysis by GC/MS using SIM achieves high sensitivity and selectivity for the detection and quantitation of organic compounds in complex environmental mixtures. In the SIM technique, the mass spectrometer is repetitively tuned to preselected ions. The ion chosen for monitoring in each series of PCDDs was the molecular ion of greatest relative abundance in the isotope cluster. These ions and classes were: m / e 321.9, tetrachlorodibenzo-pdioxins; m / e 355.9, pentachlorodibenzo-p-dioxins;m / e 389.9, hexachlorodibenzo-p-dioxin; m / e 425.9, heptachlorodibenzo-pdioxins; and m l e 459.7, octachlorodiobenzo-p-dioxin. Filtering Apparatus. A filtering apparatus was designed to combine into one operation two steps which were possible sources for sample loss or contamination. These two steps were: physical separation of fly ash and solvent, and transfer of solvent to a flask for volume reduction by rotary evaporation. Use of this filtering apparatus which is shown in Figure 1 resulted in less sample handling and a reduction in the amount of glassware needed for analysis of fly ash samples. A medium porosity sintered-glass crucible was modified with a 10-cm long, 8-mm o.d., 6-mm i.d. glass stem that was fused t o the crucible. The crucible base (31-mm i.d.) was tapered at approximately 30' over a distance of 2.2 cm and fit securely in a rubber filtering aid which connected modified crucible and glass union. Aspirator vacuum when applied to the glass union in the assembled apparatus was used to rapidly draw solvent through the glass modified crucible to a 300-mL, flabbottomed boiling flask. A water trap was positioned between apparatus and aspirator which were joined by thick-wall vacuum tubing.
RESULTS AND DISCUSSION Reproducibility of ultrasonic extraction of organic compounds in analysis of fly ash from municipal incinerators was measured by SIM determination of PCDDs in benzene extracts of five replicate analyses of 01. Typical data from SIM GC/MS analysis are shown in Figure 2. Results from these analyses are given in Table I and showed standard deviations between 0.11 and 1.2 for average concentrations for PCDDs of 0.40 to 4.4 ng/g. These values were based on comparisons between peak heights of SIM plots for samples and 30 ng of 1,2,3,4-tetrachlorodibenzo-p-dioxin. This isomer, which is one of the less toxic TCDDs, was the only standard available for
Figure 1. Diagram of filtering apparatus
use in this study. These results show the combination of ultrasonic extraction with rapid sample handling using the filtering device has acceptable precision for most routine or survey analysis of fly ash for PCDDs and other toxic organic compounds at ng/g concentration levels. Additionally, this technique may be useful in analysis of fly ash samples which contain fine particulates that present problems during Soxhlet extraction. Such problems include movement of particulate matter to the refluxing flask and obstruction of solvent flow through the extraction thimble. Although accuracy and absolute recovery efficiencies were not determined, comparisons may be made with results from analysis using conventional Soxhlet extraction methods. The estimated total concentrations of TCDDs of 9 ng/g compares favorably with a value of 12 ng/g which was determined previously using Soxhlet extractions ( I ) . Relative concentrations of resolved components within each PCBD series were similar to those seen in the earlier analysis and apparent differences may be attributed to changes in chromatographic resolution. Both the 1,2,3,4-TCDD standard solution and a procedure blank were analyzed under SIM conditions identical
ANALYTICAL CHEMISTRY, VOL. 52, NO. 9, AUGUST 1980
i
IDN 7
OCTRCHLDRODI6ENZO-P-DlDXlN
3.
n .7
A l D N 72S.B
t
1495
I
FULL. SCHLE = 5 7 . 9
!
J FULL
SCRLE = 297.9
I
HEXRCHLORODI6ENZO-P-DIOXINS
IDN 3SS.9 FULL SCALE
__
708.6
iI
PENTRCHLORODI0ENZO-P-~lOXl~S
I ION 321.5 FULL SCALE
--
= 763.1
1
TETRRCHLORODI6ENZO-P-DIOXINS
1 1.1 ' 2 . 1
-
'q.1
'6.1
'6.1
'E.1 ".I '26.1
'lW.1'l2.1'lV
'a.m ' 3 . 1 ' Z . 1 ' N . l
' 1 . 1 ' S . 1 ' W . 1 'La.1 ' W . 1 "6.1 ' 9 . 1
'-.I
MINUTES 3
I
J
Figure 2. SIM mass chromatograms of ultrasonic extract, replicate number 1 PENTRCHLDRDBENZENE
ION 2 5 2 . I
FS = I 1 7 2 PY R E N E
FLUORRNTHENE
lClN 2 0 2 . I F 5 = 376
h
PHTHRLRTE ESTER5
h
*
I
.
ION
1qg.1
F 5 = 1676
METHYL PHTHRLRTE
- -F5 METHYL E 5 T E R 5 ILL
N-HYDRDCRRBONS
I O N 163.1 = 79 ION 7 q . I F5 = 7 3 I O N 57.1 F 5 = 931
T . I .C. F 5 = I0000
0
5
I0
15
20
2s
30
35
Li0
Lis
50
MINUTE5
Figure 3. Total ion chromatogram and six mass chromatograms from GC/MS analysis of ultrasonic extract of fly ash mixture using benzene
to those used for extract analysis and no PCDDs were detected in the procedure blank using estimated levels of detection of 0.05 to 0.1 ng/g. T h e resolution value for heptachlorodibenzo-p-dioxins was 0.6 although values of 1.2 have been
routinely obtained for the same pair using other columns containing Aue Packing ( I ) . Clearly, the use of more efficient packed columns or capillary columns will aid in the identification of specific isomers; however, the results presented here
1496
ANALYTICAL CHEMISTRY, VOL. 52, NO. 9, AUGUST 1980
Table 11. Ratios of Abundance Values between Selected Pairs of Compounds
no.
pair biphenyl/ pentachlorobenzene pentadecanel pentachlorobenzene acenaphthalene1 pentachlorobenzene hexachloro benzene/ pentachlorobenzene an thracenel pentachlorobenzene dibutyl phthalate/ pentachlorobenzene anthracenelbiphenyl anthracenelacenaphthalene
Extraction Techniques ultrasonic Soxhlet 0.12
0.13
0.20
0.10
0.14
0.27
0.21
2.2
0.30
0.83
0.15
0.43
2.6 2.1
6.4 3.1
are intended to assess the ultrasonic extraction technique and not t o maximize resolution. Results which were obtained from G C / M S analysis of benzene concentrates from ultrasonic extraction of the fly ash mixture are shown in Figure 3 and an abbreviated list of ratios of abundance between selected pairs of compounds is given for ultrasonic extraction and Soxhlet extraction in Table 11. T h e mass chromatograms in Figure 3 show that ultrasonic extraction recovers the same organic compounds of those which were monitored as the Soxhlet extraction method, even though the compounds may vary widely in structure or molecular weight. However, quantitative differences exist in relative recovery efficiencies between these techniques. The differences are shown as ratios of total abundance values using mass spectra for various matched pairs of organic compounds. Abundance values for Soxhlet extraction from previous work (1) were calculated from separate extractions of samples 01 a n d 0 2 and corrected for mixture composition. The abundance values for the ultrasonic extraction method were based on direct analysis of the mixed sample. Ratios from both these analyses are listed in Table I1 and have estimated reproducibilities of f0.1 to 0.5. The first three pairs contained compounds which eluted within a few minutes of each other on Aue Packing. The values for these ratios are the same within experimental error. T h e remaining five pairs contained compounds which are more separated in elution times and showed greater differences in ratios between the two techniques. Two possible explanations for these differences are (1) extractions with the Soxhlet apparatus recover higher molecular weight compounds more efficiently than extractions
with ultrasonic agitation or (2) more volatile components are lost during the extended extraction times with the Soxhlet apparatus and a t temperatures near 100 OC. Which, if either, of these effects accounts for the differences in ratios is unknown. Although preliminary results (20) from a more closely controlled study confirmed the reduced recovery efficiency for PCDDs with ultrasonic extraction in comparison to Soxhlet extraction, these results show that ultrasonic extraction of fly ash when combined with a rapid filtering device is an adequate technique for analysis of samples or in situations where Soxhlet extraction in unnecessary or unworkable. Savings in glassware cleaning, expensive solvents, extraction times, and sample handling make ultrasonic extraction suitable for use with GC/MS analysis of fly ash samples in routine or survey studies.
LITERATURE CITED (1) Eiceman, G. A.; Clement, R. E.; Karasek, F. W. Anal. Chem. 1878, 57, 2343. (2) Cantrell, J. S.;Webb, N. C.; Mabis. A. J. Acta Clystal!ogr.,Sect. 131869, 25,50. (3) Rappe, C.; b r a , A.; Euser, H. R.; Bosshardt, H-P. Chemosphere 1877, 6 , 231. (4) Bertoni, G.; Brocco, D.; Dipalo, V.; Liberti, A,; Possanzini, M.;Bruwer, F. Anal. Chem. 1878. 50,732. (5) Kimmig, J.: Schuiz, K. H. Naturwissinschaffen 1857, 4 4 , 337. (6) Galston, A. W. Science 1876, 1967, 1067. (7) Wooton, J. C.; Courchene, W. L. J . Agric. Food Chem. 1864, 72, 94. (8) Schwetz, B. A.; Norris, J. M.; Sparschir, G. L.; Rowe, V. K.; Gearing, P. J.; Emerson, J. L.; Gerbig, C. G. Environ. Heafih Perspect. 1873, 5,87. (9) Seiier, J. P. Experimentia 1873, 29, 622. (10) Sparschu, G. L.; Dunn, F. L.; Rowe, V. K. Food Cosmet. Toxicol. 1871, 9 ,405. (11) Young, A. L.; Calcagni. J. A.; Thalken, C. E.; Tremblay, J. W. "The Toxicology, Environmental Fate and Human Risk of Herbicide Orange and Its Associated Dioxlns"; United States Air Force, Occupational and Environmental Health Laboratory Report TR-78-92, 1978. (12) Hill, H. H.. Jr.; Chan, K. W.; Karasek, F. W. J . Chromatcgr. 1877, 137, 245. (13) Broddin, G.; Van Vaech, L.; Van Cauwenberghe, K. Atmos. Environ. 1877, 7 1 , 1061. (14) "The Trace Chemistries of Fire-A Source of and Routes for the Entry of Chlorinated Dioxins Into the Environment"; The Chlorinated Dioxin Task Force, Michigan Division Dow Chemical, Midland, Mich., 1978. (15) Oiie, K.; Vermerien, P. L.; Hutzinger, 0. Chemosphere 1978, 7 ,165. (16) Golden. C.; Sawichi, E. Anal. Left. 1978, A i l , 1051. (17) Chatd, G.; Casteynaro, M.; Roche, J. L.; Fantanges, R. Anal. Chim. Acta 1871, 53,259. (18) Aue, W. A.; Hastings, C. R.; Kapih, S. J . Chromatogr. 1973, 77,299. (19) Dickson, L. C. "Software Improvements for GC/MS/Calculator used In Trace Organic Analysis of Environmental Samples"; Department of Chemistry Report, University of Waterloo, Waterloo, Ontario, April 1979. (20) Bower, W. D.: Eiceman, G. A,; Karasek, F. W.; Parsons, M. L., unpublished results.
RECEIVED for review December 21, 1979. Accepted May 15, 1980. This work was supported by the Air Resources Branch, Ontario Ministry of the Environment.
