481
Anal. Cham. 1981, 53, 461-463
LITERATURE CITED
correlation of ', with ambient concentration (correlation constant was 0.87), where EK' was the slope of the lines obtained from plotting the concentration in the extract against t1/2, at constant Y. By use of the values of D and K, corrected to 25 °C, the apparent extraction efficiency varied from 0.71 at Y = 5 ppm (t = 8 h) to 1.43 at Y = 20 ppm (t = 8 h). It was presumed that the difference between these values of E and the estimate obtained from Figure 3 reflect both the difference in the approach to equilibrium and the limited accuracy of Figure 3 at very low extract concentrations. Although Figure 2 can be used as a calibration curve for the dosimeter, it should be noted that the ambient concentration during these experiments was held constant. Furthermore, the value of Y which would be obtained from this curve would not be strictly identical with the time weighted average concentration that is normally used in workplace dosimetry. However, preliminary results from computer models of the variable concentration condition indicated that the average Y obtained from Figure 2 is within a few percent of the true time weighted average. Further work is still needed to define the nature of the average obtained from use of this dosimeter and the effect of variable ambient concentration on dosimeter response.
(1) Bailey, A.; Holllngdale-Smlth, P. A. Ann. Occup. Hyg. 1977, 20, 345. (2) Gossellnk, D. W.; Braun, D. L; Mullins, . E.; Rodriguez, S. T. 3M Co.
(3) (4) (5) (6)
(7)
(8)
(9)
(10) (11) (12)
Technical Literature (reprint of paper presented at American Industrial Hygiene Association Annual Meeting, Los Angeles, CA, 1978). Bamberger, R. L.; Esposito, G. G.; Jacobs, B. W.; Podolak, G. E.; Mazur, J. F. AIHA J. 1978, 39, 701. West, P. W.; Relszner, K. D. AIHA J. 1978, 39, 645. Chem. Eng. (N.Y.) 1978, July 16, 65. McGregor, R. "Diffusion and Sorption In Fibres and Films”, Academic Press: London, 1974; Vol. 1, p 212. Saltzman, B. E. “The Industrial Environment—Its Evaluation and Control"; NIOSH, S/N 017-001-00396-4; U.S. Government Printing Office: Washington, DC, 1977; Chapter 12, p 123. NIOSH Manual of Analytical Methods, Vol. 1, Method No. 127, DHEW (NIOSH) Publication No. 77-157-A; U.S. Government Printing Office: Washington, DC, 1977. Crank, J.; Park, G. S. “Diffusion In Polymers"; Academic Press; London, 1968; pp 15-25. Hayes, M. J.; Park, G. S. Trans. Faraday Soc. 1955, 51, 1134-1142. Gee, G.; Treakx, L. R. G. Trans. Faraday Soc. 1942, 38, 147-164. NIOSH Criteria Document, Occupational Exposure to Benzene, No. (NIOSH) 74-137; U.S. Government Printing Office: Washington, DC, 1974.
Received for review August 14,1980. Accepted October 31, 1980. The authors wish to acknowledge the support of the Government of Ontario, Ministry of Labour, under Occupational Health and Safety Applied Research Grant 023/R.
Extraction Efficiencies of Polychlorinated Dibenzo-p-dioxins and Polychlorinated Dibenzofurans from Fly Ash R.
. M. Kooke, J. W. A. Lustenhouwer, K. Olie, and O. Hutzinger*
Laboratory of Environmental and Toxicological Chemistry, University of Amsterdam, Nleuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands
of PCDD and PCDF for two samples of fly ash using seven extraction methods which were described in the literature during the last few years.
Seven methods which are currently used tor the extraction of polychlorodibenzo-p -dioxins and polychlorodibenzofurans from fly ash were compared and were found to vary widely In their extraction efficiency. Generally, Soxhlet extraction with benzene or toluene gave the best results, and highest extraction efficiencies were consistently found on acid treatment of fly ash prior to extraction. Methods which Involve simple shaking or ultrasonic treatment of fly ash In an organic solvent were found unsuitable for maximum recovery of these chlorinated compounds.
EXPERIMENTAL SECTION Samples. Two 1000-g samples of fly ash from the electrostatic precipitators of different municipal incincerators were used in this study. These samples, designated as A and B, were homogenized by stirring and shaking to assure sample uniformity for all determinations. Solvents. All solvents mentioned were distilled in glass before use.
Extraction Methods. All but the first method have previously been described in the literature: (1) Fly ash (25 g) was stirred in 1 N hydrochloric acid (200 mL). After centrifugation the residual fly ash was washed with deionized water on a Büchner funnel and air-dried at room temperature. The fly ash was then extracted for 24 h with toluene by use of a Soxhlet apparatus with a glass fritted extraction thimble (8). Extractions were carried out in the dark to minimize formation of oxidation products from toluene. (2) Fly ash (10 g) was shaken manually four times with 25 mL of dichloromethane. The extracts were then combined for cleanup and analysis (5). (3) Fly ash (10 g) in 25 mL of acetone/rc-hexane (50/50) was treated in an ultrasonic bath for 5 min. This treatment was repeated four times, and the extracts were then combined for cleanup and analysis (9). (After completion of our study, B. J. Kimble informed us that an ultrasonic probe rather than a bath was used in their work (9). Relative recoveries are expected to be higher for this method than the one we report here.) (4) Fly ash (25 g) was Soxhlet extracted with dichloromethane for 24 h (10). (5) Fly ash (25 g) was Soxhlet
Currently there is considerable activity in the field of polychlorodibenzo-p-dioxin analysis. One area of particular interest is the detection and quantitation of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in fly ash from municipal incinerators, since these and other chlorinated compounds were shown (1, 2) to be associated with particulate matter in effluents from such installations. Progress in sophisticated cleanup procedures (3, 4) and chromatographic separations (5-7) now allows quantitation at the parts-per-trillion level and complete separation of some groups of isomers. A variety of methods and a number of solvents have been used for the extraction of PCDD and PCDF from fly ash; however, relative extraction efficiencies for these different procedures have not been evaluated. In this study we compare extraction efficiencies 0003-2700/81/0353-0461801.00/0
©
1981 American Chemical Society
462
·
ANALYTICAL CHEMISTRY, VOL. 53, NO. 3, MARCH 1981
Table I.
a
Measured Concentrations of Chlorinated Dibenzodioxins in Extracts from Fly Ash Sample Aa
method 6
TCDD
p5
HCDD
H,CDD
1
82
259
508
341
2
2
4
5
2
3
nd
nd
nd
nd
4
9
28 59
6
14
21 39
17
5
36
19
Results in ppb (ng/g
Table II.
For description of method
text.
see
1
nd
c
REE
=
TCDF
P5
HCDF
H7CDF
1
169
364
555
287
2 3
6
7
7
3
nd
nd 52 90
nd 45
nd 21
1
94
49
3
36 52
Results in ppb (ng/g fly ash).
Table III.
