Anal. Chem. 1997, 69, 4210-4219
Evaluation of Pressurized Fluid Extraction for the Extraction of Environmental Matrix Reference Materials Michele M. Schantz,* John J. Nichols,† and Stephen A. Wise
Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
Pressurized fluid extraction (PFE) has been evaluated for the extraction of selected polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides from the following reference materials: SRM 1649a (Urban Dust/Organics), SRM 1650 (Diesel Particulate Matter), SRM 2975 (Diesel Particulate Matter, Industrial Forklift), SRM 1941a (Organics in Marine Sediment), SRM 1944 (New York/New Jersey Waterway Sediment), SRM 2974 (Organics in Freeze-Dried Mussel Tissue), CARP-1 (Ground Whole Carp), and CARP-2 (Ground Whole Carp). Several solvent systems were evaluated for each reference material. PFE showed extraction efficiency comparable to that of Soxhlet extraction for the selected PAHs, PCB congeners, and chlorinated pesticides quantified in the air particulate, sediment, mussel tissue, and fish materials and greater extraction efficiencies for the higher molecular weight PAHs in the diesel particulate materials. The National Institute of Standards and Technology (NIST) has developed several natural matrix Standard Reference Materials (SRMs) for the determination of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides including air and diesel particulate matter, marine sediment, mussel tissue, and whale blubber.1-4 During the certification of SRMs at NIST, the results from at least two “chemically independent” analytical techniques are typically used to determine the certified concentrations of the analytes. For the extraction of PAHs, PCB congeners, and chlorinated pesticides from environmental matrix SRMs, Soxhlet extraction with a variety of solvents has been the only extraction method employed in the certification procedures. The Soxhlet extractions used in the certification of these matrices require 16-20 h of extraction time and 200-250 mL of solvent per sample. With the demand for increased productivity, faster analyses, more automation, and reduced solvent usage,5 newer extraction techniques are being developed including supercritical fluid † Current address: Massachusetts Institute of Technology, Cambridge, Massachusetts 02139. (1) Wise, S. A.; Hilpert, L. R.; Rebbert, R. E.; Sander, L. C.; Schantz, M. M.; Chesler, S. N.; May, W. E. Fresenius’ Z. Anal. Chem. 1988, 332, 573-582. (2) Wise, S. A.; Schantz, M. M.; Benner, B. A., Jr.; Hays, M. J.; Schiller, S. B. Anal. Chem. 1995, 67, 1171-1178. (3) Schantz, M. M.; Demiralp, R.; Greenberg, R. R.; Hays, M. J.; Parris, R. M.; Porter, B. J.; Poster, D. L.; Sander, L. C.; Schiller, S. B.; Sharpless, K. S.; Wise, S. A. Fresenius J. Anal. Chem. 1997, 358, 431-440. (4) Schantz, M. M.; Koster, B. J.; Oakley, L. M.; Schiller, S. B.; Wise, S. A. Anal. Chem. 1995, 34, 901-910. (5) Majors, R. E. LC-GC 1996, 14, 88-96.
extraction (SFE) and pressurized fluid extraction (PFE). SFE is a relatively fast technique and is selective.5-7 For the extraction of PCBs from soils and sediments, workers have obtained quantitative recoveries using supercritical carbon dioxide.8-10 For PAHs and pesticides, however, it is necessary either to add modifiers, such as methanol, to the supercritical carbon dioxide or to use alternative fluids such as nitrous oxide, Freon-22, and water.11-15 SFE conditions have been reported to be not only solute dependent but also matrix dependent,16 and, therefore, SFE conditions that quantitatively extract a particular compound from one matrix may not quantitatively extract the same compound from a different matrix. For example, quantitative results for PAHs have been reported for lower molecular weight PAHs (phenanthrene through chrysene) but not for higher molecular weight PAHs, such as indeno[1,2,3-cd]pyrene and benzo[ghi]perylene, for which recoveries range from 30% to 60% from an air particulate material.14 In many of the natural matrix SRMs available for organic pollutants, the concentrations of more than one class of compounds are certified. For example, in SRM 1941a (Organics in Marine Sediment)17 and SRM 1974a (Organics in Mussel Tissue [Mytilus edulis]),3 certified concentrations are reported for several PAHs, PCB congeners, and chlorinated pesticides. Therefore, the preferable extraction technique should extract all of these classes of compounds quantitatively using the same set of conditions. Recently, Richter et al.18 introduced a new extraction technique, PFE, based on elevated temperatures and pressures using liquid solvents. They reported quantitative extractions of (1) PAHs from SRM 1649 and a Certified Reference Material (CRM) marine sediment, HS-3 (National Research Council of Canada), using methylene chloride/acetone (volume ratio ) 1) as a solvent; (2) (6) Gere, D. R.; Derrico, E. M. LC-GC 1994, 12, 432-445. (7) Hawthorne, S. B.; Miller, D. J. J. Chromatogr. Sci. 1986, 24, 258-264. (8) Lee, H.-B; Peart, T. E. J. Chromatogr. A 1994, 663, 87-95. (9) Bøwadt, S.; Johansson, B.; Wunderli, S.; Zennegg, M.; de Alencastro, L. F.; Grandjean, D. Anal. Chem. 1995, 67, 2424-2430. (10) Bøwadt, S.; Johansson, B.; Pelusio, F.; Larsen, B. R.; Rovida, C. J. Chromatogr. A 1994, 662, 424-433. (11) Hawthorne, S. B.; Miller, D. J. Anal. Chem. 1987, 59, 1705-1708. (12) Ho, J. S.; Tang, P. H. J. Chromatogr. Sci. 1992, 30, 344-350. (13) Lee, H.-B.; Peart, T. E.; Hong-You, R. L.; Gere, D. R. J. Chromatogr. A 1993, 653, 83-91. (14) Hawthorne, S. B.; Yang, J.; Miller, D. J. Anal. Chem. 1994, 66, 2912-2920. (15) David, M. D.; Seiber, J. N. Anal. Chem. 1996, 68, 3038-3044. (16) Hawthorne, S. B.; Miller, D. J.; Burford, M. D.; Langenfeld, J. J.; EckertTilotta, S.; Louie, P. K. J. Chromatogr. 1993, 642, 301-317. (17) Schantz, M. M.; Benner, B. A., Jr.; Hays, M. J.; Kelly, W. R.; Vocke, R. D., Jr.; Demiralp, R.; Greenberg, R. R.; Schiller, S. B.; Lauenstein, G. G.; Wise, S. A. Fresenius’ J. Anal. Chem. 1995, 352, 166-173. (18) Richter, B. E.; Jones, B. A.; Ezzell, J. L.; Porter, N. L.; Avdalovic, N.; Pohl, C. Anal. Chem. 1996, 68, 1033-1039.
4210 Analytical Chemistry, Vol. 69, No. 20, October 15, 1997 S0003-2700(97)00299-0 This article not subject to U.S. Copyright. Publ. 1997 Am. Chem. Soc.
Figure 1. With the oven temperature held constant at 100 °C, the pressure of the PFE was varied from 1000 (6.90 MPa) to 2200 psi (15.2 MPa) for the extraction of PAHs from SRM 1944 (New York/New Jersey Waterway Sediment). B[a]A, benz[a]anthracene; B[a]P, benzo[a]pyrene; and B[ghi]P, benzo[ghi]perylene.
Figure 2. With the oven temperature held constant at 100 °C, the pressure of the PFE was varied from 1000 (6.90 MPa) to 2200 psi (15.2 MPa) for the extraction of PCB congeners and chlorinated pesticides from SRM 1944 (New York/New Jersey Waterway Sediment).
PCBs from sewage sludge using hexane/acetone (volume ratio ) 1) as a solvent, from an oyster tissue using isooctane as a solvent, and from a CRM fish tissue, CARP-1 (National Research Council of Canada), using hexane as a solvent;19 and (3) total petroleum hydrocarbons from a soil using perchloroethylene as (19) Ezzell, J.; Richter, B.; Francis, E. Am. Environ. Lab. 1996, December, 1213.
a solvent. PFE has also appeared as Method 3545 in Update III of EPA SW-846 Methods.20,21 Heemken, et al.22 compared PFE, SFE, Soxhlet extraction, ultrasonication, and methanolic saponification extraction of PAHs (20) Lesnick, B.; Fordham, O. Environ. Lab. 1995, December/January, 25-33. (21) Test Methods for Evaluating Solid Waste, Method 3545. USEPA SW-846, 3rd ed., Update III; U.S. GPO: Washington, DC, July 1995.
Analytical Chemistry, Vol. 69, No. 20, October 15, 1997
4211
Figure 3. With the pressure held constant at 2000 psi (13.8 MPa), the oven temperature of the PFE was varied from 50 to 150 °C for the extraction of PAHs from SRM 1944 (New York/New Jersey Waterway Sediment). B[a]A, benz[a]anthracene; B[a]P, benzo[a]pyrene; and B[ghi]P, benzo[ghi]perylene.
Figure 4. With the pressure held constant at 2000 psi (13.8 MPa), the oven temperature of the PFE was varied from 50 to 150 °C for the extraction of PCB congeners and chlorinated pesticides from SRM 1944 (New York/New Jersey Waterway Sediment).
and aliphatic hydrocarbons from marine sediments including the certified sediment HS-5 (National Research Council of Canada). In addition, they did a comparison of ultrasonication and PFE for (22) Heemken, O. P.; Theobald, N.; Wenclawiak, B. W. Anal. Chem. 1997, 69, 2171-2180. (23) Certificate of Analysis for Standard Reference Material 1649a, Urban Dust/ Organics, National Institute of Standards and Technology, Gaithersburg, MD, 1997.
4212
Analytical Chemistry, Vol. 69, No. 20, October 15, 1997
the extraction of PAHs, aliphatic hydrocarbons, and a limited number of chlorinated hydrocarbons from suspended particulate matter. From these samples, they found comparable results among the extraction techniques. (24) Certificate of Analysis for Standard Reference Material 1941a, Organics in Marine Sediment, National Institute of Standards and Technology, Gaithersburg, MD, 1995. (25) Schiller, S. B.; Eberhardt, K. R. Spectrochim. Acta 1991, 46, 1607-1613.
Table 1. Concentrations (Mass Fractions in µg/kg Dry Weight) of PAHs in SRM 1649a (Urban Dust/Organics) Determined Using Different Extraction Techniques and Solvents compound
certified concna
PFE (CH2Cl2)b
PFE (ACN)c
PFE (HA)d
phenanthrene anthracene fluoranthene pyrene benz[a]anthracene chrysene triphenylene benzo[k]fluoranthene benzo[e]pyrene benzo[a]pyrene perylene indeno[1,2,3-cd]pyrene benzo[ghi]perylene dibenz[a,j]anthracene benzo[b]chrysene
4140 ( 370 433.2 ( 82 6450 ( 180 5290 ( 250 2210 ( 73 3049 ( 20 1357 ( 54 1907 ( 25 3090 ( 190 2509 ( 87 646 ( 75 3080 ( 630 3999 ( 890 307 ( 31 313 ( 15
4494 405 6674 5223 2277 4617e
4319 419 6197 5360 2098 4541e
4275 439 6230 5365 2293 4521e
1894 2923 2375 642 3016 3795 317 316
1817 3014 2362 643 3309 3504 323 327
1840 2937 2355 636 3189 3728 349 301
a Each certified value is the equally weighted mean of the means from two or more independent analytical methods. Soxhlet extractions were done using methylene chloride and hexane/acetone (volume ratio ) 1) as summarized in the Certificate of Analysis for SRM 1649a23 and reported in Wise et al. 27 b Two samples were extracted using methylene chloride; concentration is the mean of the two analyses. c Two samples were extracted using acetonitrile; concentration is the mean of the two analyses. d Two samples were extracted using hexane/ acetone (volume ratio ) 1); concentration is the mean of the two analyses. e Chrysene and triphenylene coeluted under the conditions used.
In evaluating the applicability of PFE for use as an alternative method of extraction during the certification of SRMs, the conditions for the extraction of PAHs, PCB congeners, and chlorinated pesticides from SRM 1944 (New York/New Jersey
Sediment) were optimized. Using these optimized conditions, PFE was evaluated for the extraction of PAHs, PCB congeners, and chlorinated pesticides from several certified reference materials: SRM 1649a (Urban Dust/Organics), SRM 1941a (Organics in Marine Sediment), SRM 1944 (New York/New Jersey Sediment), SRM 2974 (Organics in Freeze-Dried Mussel Tissue) and two fish tissue reference materials (CARP-1 and CARP-2). The solvents used for extraction were methylene chloride, hexane/ acetone (volume ratio ) 1), and acetonitrile. Methylene chloride, toluene, and toluene/methanol (volume ratio ) 1) were also used to extract two diesel materials: SRM 1650 (Diesel Particulate Matter) and SRM 2975 (Diesel Particulate Matter, Industrial Forklift). These measurements demonstrate the comparability of PFE to Soxhlet extraction for detemination of PAHs, PCB congeners, and chlorinated pesticides in a variety of environmental matrices at different concentrations of these contaminants and the usefulness of PFE as an alternative extraction technique for the certification of natural matrix reference materials. For the diesel materials, PFE showed greater extraction efficiencies than Soxhlet extraction for the higher molecular weight PAHs. EXPERIMENTAL SECTION Materials Evaluated. SRM 1941a (Organics in Marine Sediment), SRM 1649a (Urban Dust/Organics) (note: SRM 1649a is the same material as SRM 1649, but it has been reanalyzed and reissued with new certified values), SRM 1650 (Diesel Particulate Matter), and SRM 2974 (Organics in Freeze-Dried Mussel Tissue) were obtained from the Standard Reference Materials Program, NIST (Gaithersburg, MD). Candidate SRM 1944 (New York/New Jersey Waterway Sediment) and candidate SRM 2975 (Diesel Particulate Matter, Industrial Forklift) were also used. The two fish tissue samples (CARP-1 and CARP-2) were
Table 2. PAH Concentrations (Mass Fractions in µg/kg) Determined in SRM 1650 (Diesel Particulate Matter) and SRM 2975 (Diesel Particulate Matter, Industrial Forklift) SRM 1650 compound
PFEa (Tol/MeOH)
PFEb (CH2Cl2)
fluorene phenanthrene anthracene 1-methylphenanthrene fluoranthene pyrene benz[a]anthracene chrysene/triphenylene benzo[b]fluoranthene benzo[j]fluoranthene benzo[k]fluoranthene benzo[e]pyrene benzo[a]pyrene indeno[1,2,3-cd]pyrene benzo[ghi]perylene dibenz[a,h]anthracene dibenz[a,c]anthracene picene pentaphene benzo[b]chrysene
1.29 (0.16) 72.8 (3.8) 1.53 (0.27) 33.1 (3.4) 48.3 (2.7) 42.3 (2.7) 5.72 (0.34) 24.1 (2.1) 8.43 (0.33) 3.61 (0.21) 2.93 (0.18) 7.67 (0.31) 1.45 (0.23) 5.58 (0.38) 6.56 (0.41) 0.71 (0.05) 0.50 (0.08) 0.58 (0.03) 0.27 (0.04) 0.31 (0.04)
1.15 (0.20) 72.5 (2.6) 1.47 (0.28) 31.7 (2.1) 50.2 (2.1) 48.0 (2.1) 6.46 (0.76) 23.9 (0.6) 12.3 (0.6)c 0.74 (0.02) 2.39 (0.34) 7.58 (0.29) 1.55 (0.10) 5.55 (0.73) 6.07 (0.17) 1.18 (0.10)d 0.52 (0.05) 0.26 (0.04) 0.29 (0.03)
SRM 2975 Soxhletb (CH2Cl2) 1.20 (0.13) 62.2 (2.4) 1.41 (0.08) 29.8 (0.5) 51.7 (2.1) 48.5 (0.8) 6.30 (0.19) 23.2 (1.1) 12.3 (0.4)c 2.20 (0.32) 6.68 (0.16) 1.52 (0.31) 3.59 (0.33) 5.06 (0.22) 0.69 (0.02)d 0.39 (0.01) 0.088 (0.007) 0.18 (0.02)
PFEa (Tol/MeOH)
PFEb (CH2Cl2)
Soxhletb (CH2Cl2)
0.43 (0.07) 17.2 (1.5) 0.35 (0.03) 0.98 (0.06) 25.0 (2.4) 1.04 (0.12) 0.39 (0.02) 7.94 (0.20) 8.72 (0.27)
0.44 (0.05) 18.6 (0.9) 0.36 (0.04) 0.93 (0.07) 28.9 (1.6) 1.03 (0.05) 0.34 (0.03) 8.56 (0.16) 9.78 (0.10)c
0.42 (0.04) 18.0 (0.5) 0.30 (0.01) 0.98 (0.09) 25.6 (0.8) 1.05 (0.13) 0.41 (0.08) 8.97 (0.54) 10.2 (0.8)c
0.66 (0.08) 1.09 (0.07)
