NOTES ENVIRONMENTAL FORENSICS VOLUME

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1 ENVIRONMENTAL FORENSICS NOTES VOLUME The material contained in this newsletter is intended solely for your information; it does not constitute legal or technical advice, nor should it be relied upon as such.

2 New Tools for Environmental Forensics Comprehensive Two- Dimensional Gas Chromatography for Better Characterization and Fingerprinting Kristin Robrock, Kirk O Reilly, and Don Patterson The number of chemicals measured routinely by laboratories using typical analytical methods is sometimes not sufficient for the purposes of environmental forensic investigations that involve chemical fingerprinting. For eample, petroleum hydrocarbons, coal tars, and polycyclic aromatic hydrocarbons are composed of hundreds, or even thousands, of individual compounds, most of which cannot be distinguished by conventional chromatography, which limits the number of individual compounds that can be used to identify a unique chemical signature. A relatively new technique in the field of environmental analytical chemistry comprehensive two-dimensional gas chromatography (GCGC) has enormous potential for characterizing comple chemical mitures in the environment. In addition to the large resolving power of the GCGC system, it also allows a three-dimensional visualization of the data that can support environmental and biological forensics investigations. The GCGC technique was developed in 1991, but only recently have commercial GCGC systems have become available, which are allowing this technique to emerge in the field of environmental analytical chemistry. This article describes GCGC and provides eamples of its application to environmental forensics, as well as environmental risk assessment, biomonitoring, identification of non-conventional compounds in petroleum and other mitures, and characterization of chemical properties. This article describes GCGC and provides eamples of its application to environmental forensics, as well as environmental risk assessment, biomonitoring, identification of non-conventional compounds in petroleum and other mitures, and characterization of chemical properties. What is Comprehensive GCGC? Conventional gas chromatography (GC) relies on a single high-resolution column to separate mitures of chemicals so that individual compounds can be detected and measured in the detector. However, for many chemical mitures, such as petroleum, the separations obtained by a single high-resolution column in some cases may not be sufficient to resolve and reveal potentially important constituents. Additionally, some features of conventional GC, such as the unresolved comple miture, that are prominent in weathered petroleum are not resolved by conventional GC. Figure 1 shows an eample of the separation potential of co-eluting compounds using GCGC. A B Figure 1. Separation potential of GCGC of the unresolved comple miture (UCM) found in petroleum samples. Panel A shows UCM using conventional GC, while panel B shows the resolution obtained with GCGC (Eiserbeck et al. 2014).

3 The GCGC approach uses two columns, in series, with different separation characteristics. Commonly, a polar column (that is, a column that separates waterloving chemicals such as acids) and a non-polar column (that separates alkanes, for eample) are used in tandem, so that a sample is subjected to separation in the first column followed by separation in the net column (see Figure 2). The comprehensive GCGC system can be coupled with many different detection systems to allow the generation of three-dimensional structured chromatograms, which constitute a visual fingerprint that may be characteristic of the source matri. The most powerful system involves the use of time-of-flight mass spectrometry (TOFMS), to collect full scan spectra at the sensitivity of conventional mass selective detectors in selected ion monitoring mode. The increase in sensitivity using the GCGC system (by a factor of approimately ten) is due to the focusing effect of the modulation device located between the first and the second GC columns. Through the collection of full scan spectra, many of the thousands of chemicals, in petroleum for eample, can be identified tentatively by comparing them to known spectral libraries. Comprehensive 2D GC Figure 2. Representation of how comprehensive two-dimensional gas chromatography works. On the left is a conceptual image of the analytical equipment; on the right is an image of the resulting 3D chromatogram. Benefits of Comprehensive GCGC One benefit of GCGC is that the results are presented as three-dimensional chromatograms, and usually in color, to make visual comparison of different samples easier (see Figure 3). To facilitate visual identification of the changes between samples, a difference chromatogram can be generated by subtracting the peaks in one chromatogram from the other to generate a chromatogram that highlights only the differences between the samples. Multivariate statistical techniques, such as principal component analysis, can be used with the results provided by GCGC to obtain rigorous statistical support for forensic investigations. An additional benefit to GCGC is the increased sensitivity. Due to the way the modulator works, the detection limits can be up to an order of magnitude lower than conventional chromatography. This allows for the detection of environmental chemicals at trace concentrations. Furthermore, because a sample can be analyzed once for compounds that would ordinarily require multiple different methods (such as PAHs and alkanes), smaller sample volume is required. Gasoline from Esso Calgary Gasoline from Shell Cochrane Figure 3. Eample GCGC chromatograms of gasoline from Esso Calgary and Shell Cochrane showing the difference in the fingerprint. GCGC analyses can now be conducted by numerous academic analytical laboratories. Sample etraction methods that follow EPA methods and analytical techniques are typically modified from EPA methods for conventional chromatography. 1 1 The Ontario Ministry of the Environment in Canada specifically lists analysis by GCGC as an acceptable method for analysis of environmental samples. Source: stdprodconsume/groups/lr/@ene/@resources/ documents/resource/stdprod_ pdf

4 Evolving Applications of Two-Dimensional Gas Chromatography The main purpose of GCGC is to analyze multiple co-eluting compounds in the same sample that cannot be separated using conventional onedimensional gas chromatography. The GCGC technique is particularly useful for mitures that contain hundreds, or potentially thousands, of chemicals, such as petroleum hydrocarbons (Gaines et al. 1999), coal tars (McGregor 2012), polycyclic aromatic hydrocarbons (PAHs) (Manzano et al. 2010), polychlorinated biphenyls (PCBs) (Focant 2004; Megson 2013), the flame retardants polybrominated diphenyl ethers (PBDEs) (Robrock et al. 2008), and a variety of other organic compounds. Analyzing mitures of environmental compounds with conventional chromatography requires several different analytical methods, one for each type of compound. Many different types of compounds present in the environment, such as PAHs and PCBs, can now be measured in a single analysis with GCGC (Skoczynska 2008; Eiserbeck et al. 2014). Forensics While limited to date, GCGC has good potential for environmental forensics, in that the increased resolution provides more information about environmental samples, and many more compounds can be identified and used for fingerprinting purposes (see Figure 3). Recent studies have identified new compounds for use in source identification and characterization in environmental forensic investigations that previously were not possible. Some of the recent applications include: Drilling-fluid olefins, previously indistinguishable from petroleum hydrocarbons in an oil sheen, were used recently to identify the source of the sheen, while conventional chromatography could not identify the source (Aeppli 2013). Advances in GCGC techniques enabled coal-tar analysis to distinguish among different coal-tar mitures, which could not be done by conventional forensic techniques (McGregor 2012). GCGC has also been used to identify the sources of weathered gasoline, which typically consists of a comple miture of unresolved individual degradation products that are difficult to fingerprint (Gaines et al. 1999). GCGC has also been used to identify accelerants used in arson cases (Taylor et al. 2012). A common use of forensic analysis is to characterize the sources of polycyclic aromatic hydrocarbons (PAHs) in soils and sediments. While currently available tools allow for differentiation of various sources (Boehm 2006), challenges remain when parsing the contribution of materials that contain similar PAH profiles (O Reilly et al. 2014). Sediment in an urban river may be affected by historical contributions of numerous similar industrial processes, as well as ongoing atmospheric contributions. The key to separating these contributions is finding some unique compound or pattern of compounds in each source. A focus of current research is to combine improvements in GCGC separation, together with multivariate data evaluation techniques, to better characterize waste associated with manufactured gas plant processes and their contribution to offsite contamination (McGregor et al 2011, 2012) (see Figure 4). 2nd Dimension Retention (s) st Dimension Retention Time (min) The GCGC technique is particularly useful for mitures that contain hundreds, or potentially thousands, of chemicals, such as petroleum hydrocarbons, coal tars, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), the flame retardants polybrominated diphenyl ethers (PBDEs), and a variety of other organic compounds. Figure 4. Analysis by GCGC-ECD of polychlorinated biphenyls, polybrominated biphenyls, polychlorinated diphenyl ethers, polybrominated diphenyl ethers, polychlorinated dibenzothiophenes, polychlorinated naphthalenes, polychlorinated dibenzodioins/furans, organochlorinated pesticides, individual toaphene standards (with permission from Korytar 2006).

5 Identification of Nonconventional Compounds GCGC has also been used to identify degradation metabolites of comple mitures of chemicals, and to elucidate degradation pathways for compounds that can co-elute. With petroleum hydrocarbons, degradation products may appear indistinguishable from the original parent compounds using certain analytical procedures, and thus, it may not be evident that natural attenuation is occurring. GCGC can better reveal the weathering processes of petroleum hydrocarbons released to the environment and identify degradation products, which are helpful for agedating of contaminant releases. The GCGC technique, coupled with TOFMS, can also be used for nontargeted analyses, or in other words, to analyze environmental samples for previously unidentified compounds that are not detected with traditional GC. These non-targeted compounds can be useful components of an environmental fingerprint for identifying sources of contaminant release. GCGC can better reveal the weathering processes of petroleum hydrocarbons released to the environment and identify degradation products, which are helpful for age-dating of contaminant releases. Biomonitoring and Metabolomics Beyond environmental forensics applications, GCGC can be used for biomonitoring and metabolomics. Specifically, it can be used to detect thousands of compounds in human blood or urine in a single sample, to create a picture of human eposure to chemicals (see Figure 5). Due to the increased sensitivity of GCGC, smaller biological samples are required, which can make sample collection from subjects easier, or even possible. Figure 5. Etract of a human urine sample after deconjugation of PAHs. Determination of Chemical Properties GCGC can also be used to estimate important characteristics of both identified and unidentified compounds (Nabi et al. 2014) without having to conduct lengthy eperiments. Two factors that influence the fate, transport, and toicity of a chemical are its volatility and polarity (i.e., whether a chemical is water soluble or not). Because these characteristics are also the basis of the two-dimensional GC separation, a chemical s retention time on the first column can be related to its volatility, while the retention time on the second column depends on its polarity. While still the subject of research, recent studies have evaluated the use of GCGC to assess losses of volatiles from an oil spill, long-term transport of chlorinated compounds, and as a means of predicting bioaccumulation and aquatic toicity (Gros et al. 2014; Nabi et al. 2014; Tcaciuc et al. 2012). While these estimates can be useful, the lack of data from standard toicity tests raises challenges when assessing risks associated with many of the compounds detected by GCGC. Pros and Cons GCGC with TOFMS is a potentially powerful yet still evolving technique. While distinct benefits can be gained from using GCGC, with respect to the increased resolution of chemical fingerprints, the ability to obtain more information from a single analysis, and the potential to use smaller sample sizes, this method also has its drawbacks. While mass spectrometry may allow tentative identification of certain compounds, definite identification and quantification of the tentatively identified compounds still depend on the availability of standards for each compound. Although GCGC is used in a number of academic labs, the availability of this type of analysis in commercial laboratories is still limited and standard methods are not yet available. Furthermore, detections of previously unknown compounds in environmental or human samples may raise challenging questions as the analytical chemistry gets ahead of our understanding of the implications for potential health effects or environmental risks, or for determining causation. Another current drawback of using GCGC is the lack of a chemical profile library for potential sources. Application of environmental forensics depends, in part, on the availability of data collected from a wide range of sites and sources. This knowledge is important when practitioners evaluate site specific results. As a relatively new method, it will take

6 time for useful GCGC databases to be developed. The lack of standard methods, which increases the difficulty of comparing results from different studies, will also need to be resolved. These problems should decrease as the use of GCGC increases. Case Study: Identifying Petroleum Biodegradation Products In an effort to better manage remediation, Eponent is working within an integrated team of chemists, toicologists, and hydrogeologists to characterize microbial metabolites of motor fuels in groundwater. Typically, treatment goals are based on risks associated with petroleum. Because of uncertainty in the nature of fuel metabolites, some regulators require the use of conventional chromatography methods that cannot distinguish between hydrocarbons and their degradation intermediates. GCGC TOFMS analysis of groundwater from actual sites affected by motor fuels identified more than 1,200 individual compounds, and determined that, in many cases, the only ones still remaining in the dissolved plume are metabolites of petroleum degradation (Mohler et al. 2013). A toicological evaluation of the various classes of these compounds indicated that their toicological risk was low compared to petroleum (Zemo et al. 2013). The results are being used to negotiate appropriate treatment goals and implement improved methods for groundwater monitoring. Conclusions GCGC is an emerging analytical tool in environmental chemistry. It allows better resolution and identification of chemical mitures in the environment, and has the potential to provide clearer sample and source fingerprints. These capabilities make GCGC a potentially useful tool in environmental forensics. References Boehm PD Polycyclic aromatic hydrocarbons (PAHs). In: Morrison R, Murphy B (Eds.), Environmental Forensics A Contaminant-Specific Approach. Elsevier, New York. Eiserbeck C, Nelson RK, Reddy CM, Grice K Advances in comprehensive twodimensional gas chromatography (GCGC). In: Grice K (Ed.), Principles and Practice of Analytical Techniques in Geosciences. RSC Publishing, Ofordshire, UK. Focant J, Sjödin A, Patterson Jr. D Improved separation of the 209 PCBs using GCGC-TOFMS. Organohalogen Compounds 66: Gaines RB, Frysinger GS, Hendrick-Smith MS, Stuart JD Oil spill source identification by comprehensive two-dimensional gas chromatography. Environ Sci Technol 33: Gros J, Nabi D, Würz B, Wick LY, Brussaard CPD, Huisman J, van der Meer JR, Reddy CM, Arey JS First day of an oil spill on the open sea: early mass transfers of hydrocarbons to air and water. Environ Sci Technol 48: Korytar, P Comprehensive two-dimensional gas chromatography with selective detection for the trace analysis of organohalogenated contaminants. Ph.D. thesis, Vrije Universiteit, Amsterdam. Manzano C, Luo W, Pankow J, Synovec R, Simonich S Use of GCGC-ToFMS and the third order advantage for compound-specific stable isotope analysis of polycyclic aromatic hydrocarbons in particulate matter. American Association for Aerosol Research 29th Annual Conference. McGregor L Environmental forensic investigation of coal tars from former manufactured gas plants. PhD thesis, Department of Civil Engineering, University of Strathclyde. McGregor LA, Gauchotte-Lindsay C, Nic Daeid N, Thomas R, Daly P, Kalin RM. 2011, Ultra resolution chemical fingerprinting of dense non-aqueous phase liquids from manufactured gas plants by reversed phase comprehensive two-dimensional gas chromatography. J Chromatogr 1218: McGregor LA, Gauchotte-Lindsay C, Nic Daeid N, Thomas R, Daly P, Kalin RM Multivariate statistical methods for the environmental forensic classification of coal tars from former manufactured gas plants. Environ Sci Technol 46: Megson D, Kalin R, Worsfold PJ, Gauchotte-Lindsay C, Patterson Jr. DG, Lohan MC, Comber S, Brown TA, O Sullivan G Fingerprinting polychlorinated biphenyls in environmental samples using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry. J Chromato, 1318:

7 Mohler RE, O Reilly KT, Zemo DA, Tiwary AK, Magaw RI, Synowiec KA Nontargeted analysis of petroleum metabolites in groundwater using GC GC TOFMS. Environ Sci Technol 47(18): Nabi D, Gros J, Brussaard CPD Arey JS Mapping environmental partitioning properties of nonpolar comple mitures by use of GC GC. Environ Sci Technol 48: O Reilly K, Pietari J, Boehm P Parsing pyrogenic PAHs: Forensic chemistry, receptor models, and source control policy. Integ Environ Assess Manag DOI / ieam Robrock KR, Korytár P, Alvarez-Cohen L Pathways for the anaerobic microbial debromination of polybrominated diphenyl ethers. Environ Sci Technol 42: Skoczynska E, Korytár P, De Boer J Maimizing chromatographic information from environmental etracts by GCGC-ToF-MS. Environ Sci Technol 42: Taylor CM, Rosenhan AK, Raines JM, Rodriguez JM An arson investigation by using comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry. Forensic Res 3:9. Tcaciuc AP, Nelson RK, Reddy CM, Gschwend PM Estimating phospholipid membrane water partition coefficients using comprehensive two-dimensional gas chromatography. Environ Sci Technol 46: Zemo DA, O Reilly KT, Mohler RE, Tiwary AK, Magaw RI, Synowiec KA Nature and estimated human toicity of polar metabolite mitures in groundwater quantified as TPHd/DRO at biodegrading fuel release sites. Groundwater Monit Remed 33(4): About Eponent Central to Eponent s environmental epertise is a deep capability in environmental forensics. We have applied our epertise and eperience to a wide variety of situations: refineries, former manufactured gas plants, mines, smelters, foundries, pulp and paper mills, wood treatment facilities, oil spills, fuel terminals, and many manufacturing facilities with contaminants in air, groundwater, surface water, sediment, and soil. We have more than 30 scientists and engineers with a variety of eperience in environmental forensics. Please contact Kristin Robrock, Kirk O Reilly, or Don Patterson at Eponent if you would like additional information on this issue of our Environmental Forensics Notes. Click here for more information on our Environmental Forensics services. Click here to view our previous newsletters. For more information on Eponent s environmental services, contact: Paul D. Boehm, Ph.D. Principal Scientist and Group Vice President, Environmental Group (978) pboehm@eponent.com