Expedited Field Analysis Method for Polychlorinated Biphenyls. Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio

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1 1 / Expedited Field Analysis Method for Polychlorinated Biphenyls (PCBs) in Soil using Portable Gas Chromatography/Mass Spectrometry 4 5 Mengliang Zhang 1, Natalie A. Kruse 2, Jennifer R. Bowman 2, Glen P. Jackson 3, Center for Intelligent Chemical Instrumentation, Clippinger Laboratories, Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio , USA Voinovich School of Leadership and Public Affairs, Ohio University, Athens, OH USA Forensic and Investigative Science Program, West Virginia University, Morgantown, WV USA. 4 C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV USA Abstract An expedited field analysis method was developed for the determination of polychlorinated biphenyls (PCBs) in soil matrices using a portable gas chromatography/mass spectrometry (GC/MS). Soil samples of Corresponding author: Tel: address: Glen.Jackson@mail.wvu.edu

2 2 / approximately 0.5 g were measured with a portable scale and PCBs were extracted by headspace solid phase microextraction (SPME) with a 100 µm polydimethylsiloxane (PDMS) fiber. Two milliliters of 0.2 M potassium permanganate and 0.5 ml of 6 M sulfuric acid solution were added to the soil matrices to facilitate the extraction of PCBs. The extraction was performed for 30 min at 100 C in a portable heating block that was powered by a generator. The instrumental analysis time of the portable GC/MS instrument is less than 7 min and ran off an internal battery and helium cylinder. Six commercial PCB mixtures, Aroclor 1016, 1221, 1232, 1242, 1248, 1254 and 1260, could be classified based on the GC chromatograms and mass spectra. The detection limit of this method for Aroclor 1260 in soil matrices is approximately 10 ppm, which is sufficient for guiding remediation efforts in contaminated sites. This method was applicable to the on-site analysis of PCBs with the analysis time at about 37 min for each sample Keywords: Polychlorinated biphenyls, Aroclor, solid phase microextraction, fast gas chromatography, portable mass spectrometer

3 3 / Introduction Polychlorinated biphenyls (PCBs) are a class of synthetic toxic organic compounds that can cause various human health problems, such as neurotoxicity, dermatological, and pulmonary diseases [1]. As persistent organic pollutants (POPs), PCBs are very stable and resistant to environmental degradation. Although they have been banned in the United States since 1977, PCBs can still be found in the environment. In terms of environmental forensics, the ability to identify the Aroclor from which a PCB may have originated is a valuable provenancing tool. The term Aroclor is a commercial name for PCB products and different Aroclors comprise different types and amounts of the 209 possible PCB congeners. The US Environmental Protection Agency (EPA) recommend the cleanup level for PCB contaminated soil in low occupancy areas is less than 25 ppm [2] Gas chromatography (GC) based systems such as GC coupled with electron capture detection (ECD), electrolytic conductivity detection (ELCD), or mass spectrometry (MS) detector are the most commonly used methods to analyze PCBs. For qualitative analyses of PCBs in the environment, one can attempt to identify the various congeners of PCBs in a sample and compare the distribution to PCBs from different primary or secondary sources, such as Aroclors, soils or sediments samples. Aroclor analyses are based on the assumption that no significant change of congener composition in the Aroclor occurs under the environmental conditions. For quantitation

4 4 / of PCBs, two methods are currently used: Aroclor-based methods and congener-specific methods. EPA method 8082 is relies on GC-ECD instrumentation to analyze PCBs and enables the quantitation as individual PCBs or as Aroclors via pattern recognition algorithms. This method can quantify PCBs in solid (e.g. soil) or aqueous matrices [3]. EPA Method 1668 is a congener-specific method used to measure individual PCB congeners in water, soil, sediment, and tissue by high resolution gas chromatography (HRGC)/high resolution mass spectrometry (HRMS) [4]. High-resolution chromatography and extensive sample preparation are both necessary for full congener-specific analysis. Compared with congener-specific methods, Aroclor-based methods have high utility in identification of neat mixture and preliminary site screening. Aroclor analysis has advantages such as lower cost, shorter analysis times and less burdensome requirements of advanced instrumentation Extraction methods are typically required for the analyses of PCB in environmental matrices. Many classical extraction techniques have been applied to PCB analysis, including Soxhlet extraction [4-6], liquid/liquid extraction (LLE) [1,3,4,7], solid-phase extraction (SPE) [8-10], and pressurized fluid extraction [11-14]. However, these methods have experienced some shortcomings that limit their application to highthroughput or on-site analysis. These limitations include low extraction efficiencies, long extraction times, large volumes of solvent and large,

5 5 / power-demanding equipment. Therefore, faster extraction methods with high efficiency and low cost have been developed in recent years such as vortex assisted liquid-liquid microextraction (VALLME) [1], dispersive liquid liquid microextraction (DLLME) [11], hollow-fiber liquid-phase microextraction (HF-LPME) [15,16], and solid-phase microextraction (SPME) [17-20]. Among these methods, SPME meets the need for rapid sampling and sample preparation both in laboratory and on-site analysis because it is a solvent-free sample preparation technique that integrates extraction and enrichment into one solventless step [21] Currently, the analysis of PCBs requires that the samples be collected, packaged and transported to a laboratory for preservation and laboratory analysis. This is a time consuming process and adds sources of variance and complexity to each sample s history, so significant attention needs to be paid to method blanks and controls to account for the changing environmental conditions during handling, transportation and storage. To overcome these limitations, on-site analysis can be considerably more cost effective since up to 70% cost can be reduced from on-site analysis compared with those made using a stationary laboratory [22] Described in this paper is a sub-40 minute analysis method for the determination of PCBs in soil samples using a portable GC/MS instrument with headspace SPME. The method used a battery-powered portable GC/MS, a SPME sampling device, a 1000-W portable generator, a portable

6 6 / heating block and a portable scale to sample and analyze PCBs in soil samples on site. The sample preparation step was accomplished within 30 min and the instrumental analysis required less than 7 min. The limits of detection of proposed method are 10 ppm Materials and methods Portable GC/MS The Guardion 8 GC/MS (Torion Technologies, American Fork, Utah, USA) consists of a low thermal mass GC and a miniature toroidal ion trap mass analyzer (TMS). The system uses a fast heating low thermal mass injector and a miniature vacuum system, dual-stage diaphragm roughing pump and a turbo-molecular pump. The instrument can be ready for an injection within 3 minutes of powering on. A 90-cm 3 disposable helium cartridge and a rechargeable battery provide the carrier gas and power to the GC/MS system, which enable the portable stand-alone instrument to be used in the field without any other peripherals. The entire system weighs about 13 kg (28 lb) and is 47 cm 36 cm 18 cm ( in.). The instrument can be operated from the on-board color touch LCD screen, or via a laptop connection. Commercially available LTM GC columns from Supelco can be used. In these studies, the column was an MXT-5, 5 m 0.1 mm ID capillary column chemically bonded with 5% diphenyl/95% dimethyl polysiloxane, 0.4 µm film thickness.

7 7 / Devices for SPME extraction The SPME sampling device (Custodion ) provided by Torion is specially designed to be field-portable and easy to operate. The mechanism of the SPME holder is similar to automatic ballpoint pens. The SPME fiber can be extended out of or withdrawn into a protective metal needle just by pushing the plunger on top of the holder. Commercial SPME fibers from Supelco (Bellefonte, PA, USA) were used. In this study, as elsewhere, 100 µm PDMS fibers were found to be the most suitable for PCB analyses A pocket scale capable of weighing to 0.01 g (No. YA102, Ohaus, Parsippany, NJ, USA) was used to weigh soil samples in the field. 10 ml/20 ml glass headspace vials (SUN-SRI, Rockwood, TN, USA) and crimp top caps (SUN-SRI) were used for the sample collection and extraction steps. A stopwatch was used for monitoring sampling times. A portable 1000-W generator was used as backup power for instrument and power supply for the heating block. The portable heating block, which is capable of heating up to 100 C within 20 min was designed and assembled in the lab. For this heating block, the resistive heating elements were inserted into the aluminum block and a variable voltage controller was used to control the block temperature. A transparent Perspex cover was made to minimize convective heating losses, and the effect of wind or rain when operating outdoors.

8 8 / Reagents Standards used in this method include Aroclors 1016, 1221, 1232, 1242, 1248, 1254 and 1260, and an EPA 8082A PCB standard, which contains 19 PCB congeners, and were purchased from AccuStandard, Inc. (New Haven, CT, USA). Commercially available blank soil and PCB contaminated soil used to simulate the real soil samples were purchased from RT Corp (Laramie, WY, USA). A solution of 6 M H 2 SO 4 was prepared from a stock solution of 95% H 2 SO 4 (Sigma Aldrich, St. Louis, MO, USA). A solution of 0.2 M KMnO 4 was prepared from a primary solid standards (Sigma Aldrich) Blank soil was used to simulate the PCB contaminated soil samples. For example, to simulate 10 ppm Aroclor 1260 contaminated soil samples, 0.5 g blank soil was placed into the 10 ml glass vial and spiked with 50 µl of 100 ppm Aroclor 1260 standard solution. The soil was then vortexed for 2 minutes. The soil was dried in the hood at room temperature Sample preparation and analysis Two 0.5 g aliquots of each soil sample are measured in to two 10 ml glass vials. One is used for GC/MS analysis, and the other is used as a back-up or for moisture analysis. To extract PCBs from the soil samples, we added 2.5 ml 0.2 M KMnO 4 and 0.25 ml 6 M H 2 SO 4 to the 10 ml vial. After sealing the vial and vortexing for 30 seconds, the samples were extracted using headspace SPME for 30 min at 100 C.

9 9 / For the Aroclor 1260 determination, the GC/MS temperature was programed as follows: 50 C (hold for 60 s), rate 1.5 C/s to 290 C (hold for 150 s). The whole program was complete in 380 s (< 7 minutes). The injector was maintained at 280 C and SPME fiber desorption was performed in the injection port for 1 min to prevent carryover. A constant helium flow of 1.0 ml/min was used. The compounds were detected by full scan mode with a scan range mass to charge ratio (m/z) 50 to 500. The electron ion (EI) source was operated at 70 ev Results and discussion Aroclor 1260 was most frequently used for method development because of its relevance in the target application site. Tuning conditions for the portable GC/MS should be performed at least daily or on every start-up using the CALION calibration mixture (Torion) Extraction condition optimization During method development, various factors that are known to affect sample recoveries were studied. Recoveries are largely affected by extraction time, fiber type, analyte volatility, solubility, and surface adsorption to particulates. KMnO 4 in acid conditions has been proven to be an effective clean-up strategy for PCBs with the advantage of removing most of the co-extracted organic species and elemental sulfur [23]. Figure 1 and Table 1 summarize the results of extraction time and the addition of wet

10 10 / chemicals on recoveries of selected PCBs. These results indicate that 30- minute extractions with acidified KMnO 4 provide significantly better extraction recoveries for soil than the other conditions studied. Although acidic conditions were not significantly better than neutral conditions, we selected acidic conditions to have some control over the ph and because other groups have shown acidic conditions to be more reliable. Agitation may have a weak benefit, but adds complexity to the portable method, so was not used in the field. Preliminary optimization of SPME parameters were performed on a bench-top Thermo PolarisQ GC/MS [24] Peak identities and general performance The identification of specific Aroclors is based on the GC peak patterns and relative mass spectra. EPA 8082A standards, which contain 19 specific PCBs can be used to predict the general retention time windows of PCB homologs in Aroclors. Overall, the heavier PCBs have larger retention indices and longer retention times, although some exceptions exist. On the other hand, the comparison of mass spectra with National Institute of Standards and Technology (NIST) database can be important information for PCB homologs. Other databases may be used, such as a laboratory selfestablished compound library using PCB standards. A headspace SPME GC/MS chromatogram of EPA 8082A standard containing 19 PCB congeners was compared with a similar analysis of Aroclor 1260 in Figure 2. Retention

11 11 / times and fragmentation pattern similarities between the EPA standard and the Aroclor standard enable peak assignments to be made in the Aroclor mix. Peak assignment is made with the caveat that partial or complete co-elution of different PCB congeners cannot be excluded Although we did not confirm that each peak was a unique PCB congener, the retention times and mass spectra of the difference peaks enabled assignments to be made for the most abundant congener present in each chromatographic peak. The tentative assignments for several of the marked peaks in Figure 2 are PCB 66, 153, 138, 180 and To identify different Aroclors, all the samples must be collected, extracted and detected in the same condition and system. Figure 3 shows a Guardion GC/MS spectrum collected using this method and the comparison with NIST spectrum for the expected PCB. The combination of retention time, fragment ion masses and isotope envelope all provide evidence for the peak assignment. Similar comparisons were completed for each tentatively assigned peak in the different Aroclor mixes The relative abundance of different PCBs is different in each Aroclor and will therefore show characteristic peak patterns in resulting GC chromatograms (see Table S1 in supplemental material for the most abundant congeners in the Aroclors used here). Light PCBs, which have a dominant proportion of 1-3 chlorine substituents in their structures, are the

12 12 / major PCBs in Aroclor 1221, Aroclor 1016 and Aroclor Aroclors 1254 and 1260 contain relatively more chlorinated PCBs such as penta-, hexaand hepta- chlorobiphenyls (CBs). Tri-CBs and tetra-cbs are the most abundant PCBs in Aroclor 1242 and Aroclor To differentiate Aroclor 1016 and 1232, the relative amount of tri-cbs and tetra-cbs can be used; the tri-cbs are relatively more abundant in Aroclor Similarly, to compare Aroclor 1242 and 1248, tri-cbs are more abundant in Aroclor 1242 but tetra-cbs are more in Aroclor The hepta- and octa- CBs can be used as characteristic patterns for Aroclor The differences between Aroclors 1016 and 1232, 1242 and 1248 are not very clear, so care must be taken when interpreting the results The extraction and analysis conditions established for Aroclor 1260 was tested on the other common Aroclors to provide evidence that the method can distinguish between the different Aroclors. Preliminary tests were performed on Aroclor spikes added to empty vials, in the absence of soil. Recoveries from soil were shown to be ~30% those in the absence of a soil matrix, so the method should be readily extended to the identification of different Aroclors directly from soil samples The chromatograms shown in Figure 4 show obvious differences between the TIC patterns of the different Aroclors in the resulting chromatograms. Extracted ion chromatograms could be used to help identify specific

13 13 / congeners (or co-eluting structural isomers), which could be used to manually differentiate between the different Aroclors. These chromatograms provide a proof of principal that Aroclor differentiation should be possible at the level of ~10 ppm (PCB in soil) in this portable system Quantitation Calibration curves were collected on the portable GC/MS system to assess the linearity of the response function near the limits of detection of the instrument. Aroclor 1260 standard solutions with different concentrations were prepared in empty glass vials (no soil, water or modifiers) and analyzed. Different volumes of 100 ppm Aroclor 1260 solution were spiked into separate 10-mL vials. After the samples were dried in the hood under the room temperature to remove the solvent, they were sealed and then extracted by SPME for 30 min under 100 C. All the samples were analyzed using the same GC program on portable GC/MS. The results of the calibration curves collected on the Portable GC/MS and bench-top GC/MS are shown in Figure 5. The five major PCBs identified in Figure 5 show linear relationships between the concentration and instrument response (peak height or area) on both instruments. However, the portable GC/MS instrument had significantly higher (worse) detection limits and had poorer correlation values (expressed as R). Whereas the bench-top Polaris Q

14 14 / GC/MS consistently provided R values greater than 0.98, the portable GC/MS gave weaker correlation scores, but still exceeding It was found that the reproducibility of peak heights (or peak areas) of PCB congeners was worse on the portable instrument relative to the benchtop instrument; peak areas had percent relative standard deviations on the order of 20% on the portable system. This variance could contribute to the poorer linearity observed on the portable instrument Applications The real soil samples were collected at the former Portsmouth Gaseous Diffusion Plant, Portsmouth, Ohio USA. The samples were split for analysis between our laboratory and a commercial service laboratory (GEL Laboratories, LLC (GEL), Charleston, SC, USA). Five replicates were performed on each soil sample and the same soil samples were analyzed by GEL using EPA 8082 method. According to the commercial laboratory results, the concentrations in the real soil samples were too low (< 0.2 ppm) to be determined by our portable method. Indeed, these samples were below the limits of detection (LODs) of our portable method. Therefore, simulated soil samples that contained 10 ppm Aroclor 1260 were prepared for the on-site analysis demonstration. The outdoor demonstrations were performed at Endeavor Center, Piketon, OH and at Dairy Lane Park, Athens, OH in July 2012 and April 2013, respectively. Aroclor 1260 was identified and

15 15 / determined by our proposed method in the field. An example of Torion GC/MS chromatograms and mass spectrum for 10 ppm Aroclor 1260 in a simulated soil sample is shown in Figure 6. Only semi-quantitative analysis of Aroclors was possible on-site because of the difficulty in establishing the moisture content of the soil: concentrations can only meaningfully be reported relative to dry mass of soil, which cannot be assessed on-site Conclusions An on-site analysis method for the determination of PCBs and Aroclors by portable GC/TMS with SPME was developed in this study. Potassium permanganate acid solution was used to assist the PCB releasing from soil matrix. The method has the advantage of the high sample throughput, with a soil sample being prepared and analyzed about every 37 min. By adapting the headspace SPME method with portable scale and heating block, the onsite sampling and sample preparation can be perform on the field. Although the capability of the quantitative analysis for PCBs and Aroclors using this method is understated, this method can be very beneficial and cost-effective for the fast decision of environmental sample investigation. 311 Acknowledgments The research is funded by a grant from US Department of Energy, Office of Environmental Management, Portsmouth/Paducah Project Office #. The Center for Intelligent Chemical Instrumentation and Department of

16 16 / Chemistry and Biochemistry at Ohio University are acknowledged for the financial support # The project was supported by US Department of Energy. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the US Department of Energy Office of Environmental Management Portsmouth/Paducah Project Office, or of the Voinovich School of Leadership and Public Affairs at Ohio University References [1] S. Ozcan, J. Sep. Sci. 34 (2011) 574. [2] U. EPA, National Archives and Records Administration's Office of the Federal Register Electronic Code Of Federal Regulations, [3], EPA method 8082A, U.S. Environmental Protection Agency, Washington, DC, [4], EPA Method 1668C, U.S. Environmental Protection Agency, Washington, DC, [5], EPA method 1613B, US Environmental Protection Agency, Washington, DC, [6], EPA method 3540C, U.S. Environmental Protection Agency, Washington, DC, [7], U.S. Environmental Protection Agency, Washington, DC, 1980.

17 17 / [8] A. Sjodin, R.S. Jones, C.R. Lapeza, J.F. Focant, E.E. McGahee, D.G. Patterson, Anal. Chem. 76 (2004) [9] Z. Zhang, E. Ohiozebau, S.M. Rhind, J. Chromatogr. A 1218 (2011) [10] S.H. Patil, K. Banerjee, S. Dasgupta, D.P. Oulkar, S.B. Patil, M.R. Jadhav, R.H. Savant, P.G. Adsule, M.B. Deshmukh, J. Chromatogr. A 1216 (2009) [11] X. Liu, A. Zhao, A. Zhang, H. Liu, W. Xiao, C. Wang, X. Wang, J. Sep. Sci. (2011). [12] J.L. Martinez Vidal, A. Garrido Frenich, L. Barco Bonilla Mde, R. Romero-Gonzalez, J.A. Padilla Sanchez, Anal. Bioanal. Chem. 395 (2009) [13] G. Rocco, C. Toledo, I. Ahumada, B. Sepulveda, A. Canete, P. Richter, J. Chromatogr. A 1193 (2008) 32. [14] A. Muller, E. Bjorklund, C. von Holst, J. Chromatogr. A 925 (2001) 197. [15] G. Li, L. Zhang, Z. Zhang, J. Chromatogr. A 1204 (2008) 119. [16] C. Basheer, M. Vetrichelvan, S. Valiyaveettil, H.K. Lee, J. Chromatogr. A 1139 (2007) 157. [17] M. Xie, Z.Y. Yang, L.J. Bao, E.Y. Zeng, J. Chromatogr. A 1216 (2009) 4553.

18 18 / [18] Y.H. Wang, Y.Q. Li, J. Zhang, S.F. Xu, S.G. Yang, C. Sun, Anal. Chim. Acta 646 (2009) 78. [19] R. Lopez, F. Goni, A. Etxandia, E. Millan, J. Chromatogr. B 846 (2007) 298. [20] K.J. Chia, T.Y. Lee, S.D. Huang, Anal. Chim. Acta 527 (2004) 157. [21] G. Ouyang, J. Pawliszyn, Trac-Trends Anal. Chem. 25 (2006) 692. [22] T. Kotiaho, J. Mass Spectrom. 31 (1996) 1. [23] R. Montes, M. Ramil, I. Rodriguez, E. Rubi, R. Cela, J. Chromatogr. A 1124 (2006) 43. [24] M. Zhang, G.P. Jackson, N.A. Kruse, J.R. Bowman, P.d.B. Harrington, J. Sep. Sci. Submitted (2014)

19 19 / 28 Table 1. Paired t test results (the two tailed p-values) for the comparison of peak areas for five different PCB peaks under different conditions during headspace SPME extraction. Condition of soil during headspace SPME sampling 10 vs 30 min Agit. vs no agit. 1 KMnO 4 vs H 2 O H 2 O vs Soil H 2 O vs H + H 2 O vs OH * * * * * Agit. stands for agitation. *p 0.05, difference exists. Bold indicates the condition with the better recoveries

20 20 / 28 Figure 1. Bar charts showing the influence of (A) SPME sorption time, (B) agitation, (C) addition of KMnO 4 and H 2 O and (D) addition of acid and base on extraction efficiency of PCB 66, PCB 153, PCB 138, PCB 180 and PCB 170 from soil, as measured on the portable bench-top GC/MS instrument. Error bars show ±1 standard deviation (N=3 trials). Significance tests are shown in Table

21 21 / 28 PCB$153$ PCB$66$ TIC (abundance) PCB$170$ PCB$180$ PCB$138$ Time (min) Figure 2. Total ion current (TIC) chromatogram of headspace SPME of 40 µl of 100 ppm Aroclor 1260 (red) and EPA 8082A mix (blue) in the absence of soil matrix on the Torion Guardion -8 GC/MS. Peak assignments for the Aroclor mix (red) were made from the EI mass spectra and retention times but cannot exclude the possibility of congener co-elution in the Aroclor mix. 375

22 22 / 28 Figure 3. Example of mass spectra comparison for pentachlorobiphenyl between Torion Guardion -8 GC/MS data (top) with NIST database (bottom). The chlorine isotope distributions are identifiable in both spectra, especially around m/z 254 and

23 23 / 28 Figure 4. Portable GC/MS chromatograms (TIC) for headspace SPME analyses of 10 µg PCBs in soil with spikes of (A) Aroclor 1016, (B) Aroclor 1232, (C) Aroclor 1242, (D) Aroclor 1248, (E) Aroclor 1254 and (F) Aroclor 1260 in the

24 24 / 28 absence of soil matrix. The retention time windows of chromatograms for each Aroclor (upper chromatogram of each Aroclor) are shown from 3.1 min to 4.9 min. The lower chromatograms of each Aroclor show the same data in larger scale. (2CB: Dichlorobiphenyl; 3CB: Trichlorobiphenyl; 4CB: Tetrachlorobiphenyl; 5CB: Pentachlorobiphenyl; 6CB: Hexachlorobiphenyl; 7CB: Heptachlorobiphenyl; 8CB: Octachlorobiphenyl.)

25 25 / " 120" " " a) b) " Peak%Area%(PCB%180)%% 100" 80" 60" 40" Calibra2on"Line" 95%"Confidence"Interval" Peak%area%(PCB%180)%% " " " " " " Calibra0on"Line" 95%"Confidence"Interval" 20" " 382 0" 0" 1000" 2000" 3000" 4000" 5000" 6000" 7000" 8000" 9000" 10000" Spike%amount%of%Aroclor%1260%in%vial%(ng)% 0" 0" 5" 10" 15" 20" 25" 30" 35" 40" 45" 50" Amount%of%Aroclor%1260%in%vial%(ng)% Figure 5. Comparisons of headspace SPME calibration curves of Aroclor 1260 in soil matrix for the peak tentatively assigned as PCB 180 collected on a) Portable Torion Guardion -8 GC/MS (R = 0.96) and b) Bench-top Thermo Polaris Q GC/MS (R = 0.98). Note that the bench-top calibration curve covers significantly lower quantities

26 26 / 28 PDMS peaks From septum and fiber PCB peaks Time (min) Figure 6. Total ion chromatogram of Aroclor 1260 (top) and representative MS spectrum of a hexachlorobiphenyl PCB eluting at 3.85 minutes for 10 ppm Aroclor in a simulated soil sample. SPME extraction and GC/MS analysis was performed in the field in less than 40 minutes. m/z

27 27 / Figure Captions Figure 1. Bar charts showing the influence of (A) SPME sorption time, (B) agitation, (C) addition of KMnO 4 and H 2 O and (D) addition of acid and base on extraction efficiency of PCB 66, PCB 153, PCB 138, PCB 180 and PCB 170 from soil, as measured on the portable bench-top GC/MS instrument. Error bars show ±1 standard deviation (N=3 trials). Significance tests are shown in Table 1. Figure 2. Total ion current (TIC) chromatogram of headspace SPME of 40 µl of 100 ppm Aroclor 1260 (red) and EPA 8082A mix (blue) in the absence of soil matrix on the Torion Guardion -8 GC/MS. Peak assignments for the Aroclor mix (red) were made from the EI mass spectra and retention times but cannot exclude the possibility of congener co-elution in the Aroclor mix. Figure 3. Example of mass spectra comparison for pentachlorobiphenyl between Torion Guardion -8 GC/MS data (top) with NIST database (bottom). The chlorine isotope distributions are identifiable in both spectra, especially around m/z 254 and 326. Figure 4. Portable GC/MS chromatograms (TIC) for headspace SPME analyses of 10 µg PCBs in soil with spikes of (A) Aroclor 1016, (B) Aroclor 1232, (C) Aroclor 1242, (D) Aroclor 1248, (E) Aroclor 1254 and (F) Aroclor 1260 in the absence of soil matrix. The retention time windows of chromatograms for each Aroclor (upper chromatogram of each Aroclor) are shown from 3.1 min to 4.9 min. The lower chromatograms of each Aroclor show the same data in larger scale. (2CB: Dichlorobiphenyl; 3CB: Trichlorobiphenyl; 4CB: Tetrachlorobiphenyl; 5CB: Pentachlorobiphenyl; 6CB: Hexachlorobiphenyl; 7CB: Heptachlorobiphenyl; 8CB: Octachlorobiphenyl.). Figure 5. Comparisons of headspace SPME calibration curves of Aroclor 1260 in soil matrix for the peak tentatively assigned as PCB 180 collected on a) Portable Torion Guardion -8 GC/MS (R = 0.96) and b) Bench-top Thermo Polaris Q GC/MS (R = 0.98). Note that the bench-top calibration curve covers significantly lower quantities. Figure 6. Total ion chromatogram of Aroclor 1260 (top) and representative MS spectrum of a hexachlorobiphenyl PCB eluting at 3.85 minutes for 10

28 28 / ppm Aroclor in a simulated soil sample. SPME extraction and GC/MS analysis was performed in the field in less than 40 minutes.