Nontargeted comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry method and software for inventorying persistent and bioaccumulative contaminants in marine environments

Profiling of individual naphthenic acids at a composite tailings reclamation fen by comprehensive two-dimensional gas chromatography-mass spectrometry

Naphthenic acids (NAs) are naturally occurring in the Athabasca oil sands region (AOSR) and accumulate in tailings as a result of water-based extraction processes. NAs exist as a complex mixture, so the development of an analytical technique to characterize them has been an on-going challenge. The aim of this study was to use comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry to monitor individual NAs within a wetland reclamation site in the AOSR. Samples were collected from four monitoring wells at the site and the extracts were found to contain numerous resolved isomers of classical (monocyclic-, bicyclic-, adamantane-, indane-, and tetralin-type carboxylic acids) and sulfur-containing NAs (thiamonocyclic- and thiophene-type carboxylic acids). The absolute abundances of the monitored NAs were compared between four monitoring wells and unique profiles were observed at each well. Few significant changes in absolute abundances were observed over the sampling period, with the exception of one well (Well 6A). In addition, isomeric percent compositions were calculated for each set of structural isomers, and one-way analysis of variance (ANOVA) and two-dimensional hierarchical cluster analysis revealed high spatial variation at the site. However, consistent distributions were observed at each of the monitoring wells for some sets of NA isomers (such as: adamantane NAs), which may be useful for forensic applications, such as identifying sources of contamination or demonstrating biodegradation. The methods and results presented in this study demonstrate the utility of monitoring individual NAs, since both changes in absolute abundances of individual NAs and the distribution of NA isomers have the ability to provide insight into their sources and the processes controlling their concentrations that are not only of relevance to the Alberta Oil Sands, but also to other petroleum deposits and environmental systems.

Patterns of Personal Exposure to Urban Pollutants Using Personal Passive Samplers and GC × GC/ToF-MS

The performance of silicon wristband passive samplers (WB), combined with comprehensive two-dimensional gas-chromatography/time-of-flight mass-spectrometry (GC × GC/ToF-MS), for the analysis of urban derived pollutants in the personal environment was evaluated. Cumulative 5-day exposure samples from 27 individuals in areas with different geographical/socioeconomic characteristics within the Santiago Metropolitan Region (Chile) were collected during winter and summer (2016-2017). Samples were extracted without cleanup/fractionation and analyzed using targeted and nontargeted methods. The quantified semivolatile organic compounds (SVOCs, n = 33) (targeted analysis), and tentatively identified features ( n = 595-1011) (nontargeted analysis) were classified according to their use/source. Seasonal differences were observed in the targeted analysis, while seasonal and spatial differences were observed in the nontargeted analysis. Higher concentrations of combustion products were observed in winter, while higher concentrations of consumer products were found in summer. Spatial differences were observed in hierarchical clustering analysis of the nontargeted data, with distinct clusters corresponding to specific subregions of the urban area. Results from this study provide spatial and seasonal distributions of urban pollutants within an urban area and establish the utility of linking WB with nontargeted analysis as a tool to identify and prioritize new exposures to urban contaminants at the local/community level.

Use of carbon isotopic ratios in nontargeted analysis to screen for anthropogenic compounds in complex environmental matrices

Analytical data for ultra-high-performance liquid chromatography (UHPLC), nontargeted, high-resolution, mass-spectrometry (HR/MS) molecular features from a wide array of samples are used to calculate ¹³C₁¹²C_(n-1)/¹²C_n isotopologue ratios. These ratios increase with molecular carbon number roughly following a trend defined by atmospheric carbon. When the effective source reservoir ¹³C/¹²C ratio is calculated from the isotopologue ratio (assuming a fractionation factor of unity), features in biotic samples uniformly are tightly grouped, proximate to atmospheric ¹³C/¹²C ratio. In contrast, features in soil natural organic matter (NOM), dust NOM and anthropogenic compounds range from proximate to relatively divergent from atmospheric ¹³C/¹²C. For the NOM, ¹³C/¹²C ratios are consistent with an expected preferential volatilization of ¹²C, rendering features in soil NOM ¹³C-enriched and some features in dust NOM ¹³C-depleted. Anthropogenic compounds tend to diverge most dramatically from atmospheric ¹³C/¹²C, generally toward ¹³C-depletion, but pesticides we tested tended toward ¹³C-enriched. This pattern is robust and evident in: i) anthropogenic vs natural features in dust; ii) perfluorinated compounds in standards and as soil contaminants; and iii) sunscreen compounds in commercial products and wastewater. Considering the observed wide ¹³C/¹²C range for anthropogenic compounds, we suggest Rayleigh distillation during synthetic processes commonly favors one isotope over the other, rendering a source reservoir that is progressively depleted as synthesis proceeds and, consequently, generates a wide variation in ¹³C/¹²C for man-made products. However, kinetic-isotopic effects and/or synthesis from petroleum/natural gas might contribute to the anthropogenic isotopic signature as well. Regardless of cause, ¹³C/¹²C can be used to cull HR/MS molecular features that are more likely to be of anthropogenic or non-biotic origin.

Organohalogens Naturally Biosynthesized in Marine Environments and Produced as Disinfection Byproducts Alter Sarco/Endoplasmic Reticulum Ca2+ Dynamics

Contemporary sources of organohalogens produced as disinfection byproducts (DBPs) are receiving considerable attention as emerging pollutants because of their abundance, persistence, and potential to structurally mimic natural organohalogens produced by bacteria that serve signaling or toxicological functions in marine environments. Here, we tested 34 organohalogens from anthropogenic and marine sources to identify compounds active toward ryanodine receptor (RyR1), known toxicological targets of non-dioxin-like polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). [3H]Ryanodine ([3H]Ry) binding screening (≤2 μM) identified 10 highly active organohalogens. Further analysis indicated that 2,3-dibromoindole (14), tetrabromopyrrole (31), and 2,3,5-tribromopyrrole (34) at 10 μM were the most efficacious at enhancing [3H]Ry binding. Interestingly, these congeners also inhibited microsomal sarcoplasmic/endoplasmic reticulum (SR/ER) Ca2+ ATPase (SERCA1a). Dual SERCA1a inhibition and RyR1 activation triggered Ca2+ efflux from microsomal vesicles with initial rates rank ordered 31 > 34 > 14. Hexabromobipyrroles (25) enhanced [3H]Ry binding moderately with strong SERCA1a inhibition, whereas pyrrole (24), 2,3,4-tribromopyrrole (26), and ethyl-4-bromopyrrole-2-carboxylate (27) were inactive. Of three PBDE derivatives of marine origin active in the [3H]Ry assay, 4'-hydroxy-2,3',4,5',6-pentabromodiphenyl ether (18) was also a highly potent SERCA1a inhibitor. Molecular targets of marine organohalogens that are also DBPs of emerging environmental concern are likely to contribute to their toxicity.

Automating data analysis for two-dimensional gas chromatography/time-of-flight mass spectrometry non-targeted analysis of comparative samples

Non-targeted analysis of environmental samples, using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC/ToF-MS), poses significant data analysis challenges due to the large number of possible analytes. Non-targeted data analysis of complex mixtures is prone to human bias and is laborious, particularly for comparative environmental samples such as contaminated soil pre- and post-bioremediation. To address this research bottleneck, we developed OCTpy, a Python™ script that acts as a data reduction filter to automate GC × GC/ToF-MS data analysis from LECO® ChromaTOF® software and facilitates selection of analytes of interest based on peak area comparison between comparative samples. We used data from polycyclic aromatic hydrocarbon (PAH) contaminated soil, pre- and post-bioremediation, to assess the effectiveness of OCTpy in facilitating the selection of analytes that have formed or degraded following treatment. Using datasets from the soil extracts pre- and post-bioremediation, OCTpy selected, on average, 18% of the initial suggested analytes generated by the LECO® ChromaTOF® software Statistical Compare feature. Based on this list, 63-100% of the candidate analytes identified by a highly trained individual were also selected by OCTpy. This process was accomplished in several minutes per sample, whereas manual data analysis took several hours per sample. OCTpy automates the analysis of complex mixtures of comparative samples, reduces the potential for human error during heavy data handling and decreases data analysis time by at least tenfold.

Comprehensive Analysis of the Great Lakes Top Predator Fish for Novel Halogenated Organic Contaminants by GC×GC-HR-ToF Mass Spectrometry

The U.S. Environmental Protection Agency's Great Lakes Fish Monitoring and Surveillance Program (GLFMSP) has traced the fate and transport of anthropogenic chemicals in the Great Lakes region for decades. Isolating and identifying halogenated species in fish is a major challenge due to the complexity of the biological matrix. A nontargeted screening methodology was developed and applied to lake trout using a 2-dimensional gas chromatograph coupled to a high resolution time-of-flight mass spectrometer (GC×GC-HR-ToF MS). Halogenated chemicals were identified using a combination of authentic standards and library spectral matching, with molecular formula estimations provided by exact mass spectral interpretation. In addition to the halogenated chemicals currently being targeted by the GLFMSP, more than 60 nontargeted halogenated species were identified. Most appear to be metabolites or breakdown products of larger halogenated organics. The most abundant compound class was halomethoxyphenols accounting for more than 60% of the total concentration of halogenated compounds in top predator fish from all five Great Lakes illustrating the need and utility of nontargeted halogenated screening of aquatic systems using this platform.

Comprehensive Screening Links Halogenated Organic Compounds with Testosterone Levels in Male Delphinus delphis from the Southern California Bight

While environmental pollutants have been associated with changes in endocrine health in cetaceans, efforts to link contaminant exposure with hormones have largely been limited to a list of known, targeted contaminants, overlooking minimally characterized or unknown compounds of emerging concern. To address this gap, we analyzed a suite of potential endocrine disrupting halogenated organic compounds (HOCs) in blubber from 16 male short-beaked common dolphins ( Delphinus delphis) with known maturity status collected from fishery bycatch in the Southern California Bight. We employed a suspect screening mass spectrometry-based method to investigate a wide range of HOCs that were previously observed in cetaceans from the same region. Potential endocrine effects were assessed through the measurement of blubber testosterone. We detected 167 HOCs, including 81 with known anthropogenic sources, 49 of unknown origin, and 37 with known natural sources. The sum of 11 anthropogenic and 4 unknown HOC classes were negatively correlated with blubber testosterone. Evidence suggests that elevated anthropogenic HOC load contributes to impaired testosterone production in mature male D. delphis. The application of this integrative analytical approach to cetacean contaminant analysis allows for inference of the biological consequences of accumulation of HOCs and prioritization of compounds for future environmental toxicology research.

Tracking changes in composition and amount of dissolved organic matter throughout drinking water treatment plants by comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry

Dissolved organic matter (DOM) can affect the performance of water treatment processes and produce undesirable disinfection by-products during disinfection. Several studies have been undertaken on the structural characterization of DOM, but its fate during drinking water treatment processes is still not fully understood. In this work, the nontargeted screening method of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS) was used to reveal the detailed changes of different chemical classes of compounds in DOM during conventional and advanced drinking water treatment processes at three drinking water treatment plants in China. The results showed that when the dissolved organic carbon removal was low, shifts in the DOM composition could not be detected with the specific ultraviolet absorbance at 254nm, but the changes were clear in the three-dimensional fluorescence excitation-emission matrix or GC×GC-qMS analyses. Coagulation-sedimentation processes selectively removed 37-59% of the nitrogenous compounds, alcohols and aromatic hydrocarbons but increased the concentrations of halogen-containing compounds by 17-26% because of the contact time with chlorine in this step. Filtration was less efficient at removing DOM but preferentially removed 21-60% of the acids. However, other organic matter would be released from the filter (e.g., nitrogenous compounds, acids, and aromatic hydrocarbons). Biological activated carbon (BAC) treatment removed most of the compounds produced from ozonation, particularly ketones, alcohols, halogen-containing compounds and acids. However, it should be noted that certain highly polar or high molecular weight compounds not identified in this study might be released from the BAC bed. After the whole treatment processes, the concentrations of nitrogenous compounds, alcohols, alkenes, aromatic hydrocarbons and ketones were decreased more by the advanced treatment processes than by the conventional treatment processes. Alcohol and ketone removals were probably related to the reduction in protein-like materials. Alkane removal was probably related to the reduction in fulvic acid-like and humic acid-like materials.

Identification of polar transformation products and high molecular weight polycyclic aromatic hydrocarbons (PAHs) in contaminated soil following bioremediation

Bioremediation is a technique commonly used to reduce the toxicity associated with polycyclic aromatic hydrocarbons (PAHs) in contaminated soils. However, the efficacy of bioremedial applications is evaluated based on the removal of a subset of parent (or unsubstituted) PAHs and does not incorporate toxic polar transformation products or the more mutagenic high molecular weight PAHs (MW≥302amu or MW302-PAHs). Previously, an effects-directed analysis approach was used to assess the effect of bioremediation on the toxicity of a coal tar-contaminated soil. Increased genotoxicity and developmental toxicity was measured postbioremedation in the more polar soil extract fractions, as compared to the less polar fractions where the targeted PAHs eluted, and could not be attributed to the 88 target PAHs analyzed for (including selected oxygen-containing PAHs). In this study, comprehensive two-dimensional gas chromatography time-of-flight and liquid chromatography quadrupole time-of-flight mass spectrometry were used to characterize transformation products in the soil extract fractions identified as toxic, previously. Additionally, the degradation of 12MW302-PAHs, picene (MW=278) and coronene (MW=300) were evaluated following bioremediation. Non-targeted analysis resulted in the tentative identification of 10 peaks with increased intensity postbioremediation (based on mass spectral library matching and fragmentation patterns from >5000 candidate peaks in the soil extracts). Several of these compounds contained oxygen, suggesting they would be relatively polar. MW302-PAHs were not significantly degraded during bioremediation, suggesting that the carcinogenic potential associated with these PAHs might remain unchanged. The results of this study suggest that polar transformation products, and MW302-PAHs, should be considered for realistic risk assessment of bioremediated soils.

Synthesis, structure elucidation, and determination of polyhalogenated N-methylpyrroles (PMPs) in blue mussels

Polyhalogenated N-methylpyrroles (PMPs) are halogenated natural products (HNPs) recently detected in seagrass, blue mussels, and other marine organisms. In this study, we synthesized 2,3,4,5-tetrachloro-N-methylpyrrole (Cl₄-MP), 2,3,4,5-tetrabrominated-N-methylpyrrole (Br₄-MP, aka TBMP), and mixed tetrahalogenated (Cl and Br) N-methylpyrrole congeners. Use of one- and two-dimensional ¹H and ¹³C NMR verified the structures of isolated/enriched 3,4-dibromo-2,5-dichloro-N-methylpyrrole (3,4-Br₂-2,5-Cl₂-MP), 2,3,4-tribromo-5-chloro-N-methylpyrrole (2,3,4-Br₃-5-Cl-MP), and 3-bromo-2,4,5-trichloro-N-methylpyrrole (3-Br-2,4,5-Cl₃-MP). GC/EI-MS and GC/ECNI-MS mass spectra of the five PMPs were studied with regard to fragmentation pattern and individual responses which were strongly affected by the presence (or absence) of Br in α-position(s). Quantitative solutions of the synthesized standards were used to determine the elution order of isomers and to quantify PMPs in selected blue mussel samples (Mytilus sp.) from the European Atlantic coast (Spain, France), the North Sea (the Netherlands, Germany) and Baltic Sea (Germany). PMPs were detected in all samples and the concentrations ranged between 0.6 and 52 μg/kg lipids with Br₄-MP being the most abundant representative of this substance class.

Portable FAIMS: Applications and Future Perspectives

Miniaturized mass spectrometry (MMS) is optimal for a wide variety of applications that benefit from field-portable instrumentation. Like MMS, field asymmetric ion mobility spectrometry (FAIMS) has proven capable of providing in situ analysis, allowing researchers to bring the lab to the sample. FAIMS compliments MMS very well, but has the added benefit of operating at atmospheric pressure, unlike MS. This distinct advantage makes FAIMS uniquely suited for portability. Since its inception, FAIMS has been envisioned as a field-portable device, as it affords less expense and greater simplicity than many similar methods. Ideally, these are simple, robust devices that may be operated by non-professional personnel, yet still provide adequate data when in the field. While reducing the size and complexity tends to bring with it a loss of performance and accuracy, this is made up for by the incredibly high throughput and overall convenience of the instrument. Moreover, the FAIMS device used in the field can be brought back to the lab, and coupled to a conventional mass spectrometer to provide any necessary method development and compound validation. This work discusses the various considerations, uses, and applications for portable FAIMS instrumentation, and how the future of each applicable field may benefit from the development and acceptance of such a device.

Nontarget Screening with High Resolution Mass Spectrometry in the Environment: Ready to Go?

The vast, diverse universe of organic pollutants is a formidable challenge for environmental sciences, engineering, and regulation. Nontarget screening (NTS) based on high resolution mass spectrometry (HRMS) has enormous potential to help characterize this universe, but is it ready to go for real world applications? In this Feature article we argue that development of mass spectrometers with increasingly high resolution and novel couplings to both liquid and gas chromatography, combined with the integration of high performance computing, have significantly widened our analytical window and have enabled increasingly sophisticated data processing strategies, indicating a bright future for NTS. NTS has great potential for treatment assessment and pollutant prioritization within regulatory applications, as highlighted here by the case of real-time pollutant monitoring on the River Rhine. We discuss challenges for the future, including the transition from research toward solution-centered and robust, harmonized applications.

Bioelectrochemical biosensor for water toxicity detection: generation of dual signals for electrochemical assay confirmation

Toxicity assessment of water is of great important to the safety of human health and to social security because of more and more toxic compounds that are spilled into the aquatic environment. Therefore, the development of fast and reliable toxicity assessment methods is of great interest and attracts much attention. In this study, by using the electrochemical activity of Shewanella oneidensis MR-1 cells as the toxicity indicator, 3,5-dichlorophenol (DCP) as the model toxic compound, a new biosensor for water toxicity assessment was developed. Strikingly, the presence of DCP in the water significantly inhibited the maximum current output of the S. oneidensis MR-1 in a three-electrode system and also retarded the current evolution by the cells. Under the optimized conditions, the maximum current output of the biosensor was proportional to the concentration of DCP up to 30 mg/L. The half maximal inhibitory concentration of DCP determined by this biosensor is about 14.5 mg/L. Furthermore, simultaneous monitoring of the retarded time (Δt) for current generation allowed the identification of another biosensor signal in response to DCP which could be employed to verify the electrochemical result by dual confirmation. Thus, the present study has provided a reliable and promising approach for water quality assessment and risk warning of water toxicity.

Integrated Framework for Identifying Toxic Transformation Products in Complex Environmental Mixtures

Complex environmental mixtures consist of hundreds to thousands of unknown and unregulated organic compounds that may have toxicological relevance, including transformation products (TPs) of anthropogenic organic pollutants. Non-targeted analysis and suspect screening analysis offer analytical approaches for potentially identifying these toxic transformation products. However, additional tools and strategies are needed in order to reduce the number of chemicals of interest and focus analytical efforts on chemicals that may pose risks to humans and the environment. This brief review highlights recent developments in this field and suggests an integrated framework that incorporates complementary instrumental techniques, computational chemistry, and toxicity analysis, for prioritizing and identifying toxic TPs in the environment.

Nontargeted Screening of Halogenated Organic Compounds in Bottlenose Dolphins (Tursiops truncatus) from Rio de Janeiro, Brazil

To catalog the diversity and abundance of halogenated organic compounds (HOCs) accumulating in high trophic marine species from the southwestern Atlantic Ocean, tissue from bottlenose dolphins (Tursiops truncatus) stranded or incidentally captured along the coast of Rio de Janeiro, Brazil, were analyzed by a nontargeted approach based on GC×GC/TOF-MS. A total of 158 individual HOCs from 32 different structural classes were detected in the blubber of 4 adult male T. truncatus. Nearly 90% of the detected compounds are not routinely monitored in the environment. DDT-related and mirex/dechlorane-related compounds were the most abundant classes of anthropogenic origin. Methoxy-brominated diphenyl ethers (MeO-BDEs) and chlorinated methyl- and dimethyl bipyrroles (MBPs and DMBPs) were the most abundant natural products. Reported for the first time in southwestern Atlantic cetaceans and in contrast to North American marine mammals, chlorinated MBPs and DMBPs were more abundant than their brominated and/or mixed halogenated counterparts. HOC profiles in coastal T. truncatus from Brazil and California revealed a distinct difference, with a higher abundance of MeO-BDEs, mirex/dechloranes and chlorinated bipyrroles in the Brazilian dolphins. Thirty-six percent of the detected HOCs had an unknown structure. These results suggest broad geographical differences in the patterns of bioaccumulative chemicals found in the marine environment and indicate the need to develop more complete catalogs of HOCs from various marine environments.

Newly Identified DDT-Related Compounds Accumulating in Southern California Bottlenose Dolphins

Nontargeted GC×GC-TOF/MS analysis of blubber from 8 common bottlenose dolphins (Tursiops truncatus) inhabiting the Southern California Bight was performed to identify novel, bioaccumulative DDT-related compounds and to determine their abundance relative to the commonly studied DDT-related compounds. We identified 45 bioaccumulative DDT-related compounds of which the majority (80%) is not typically monitored in environmental media. Identified compounds include transformation products, technical mixture impurities such as tris(chlorophenyl)methane (TCPM), the presumed TCPM metabolite tris(chlorophenyl)methanol (TCPMOH), and structurally related compounds with unknown sources, such as hexa- to octachlorinated diphenylethene. To investigate impurities in pesticide mixtures as possible sources of these compounds, we analyzed technical DDT, the primary source of historical contamination in the region, and technical Dicofol, a current use pesticide that contains DDT-related compounds. The technical mixtures contained only 33% of the compounds identified in the blubber, suggesting that transformation products contribute to the majority of the load of DDT-related contaminants in these sentinels of ocean health. Quantitative analysis revealed that TCPM was the second most abundant compound class detected in the blubber, following DDE, and TCPMOH loads were greater than DDT. QSPR estimates verified 4,4',4″-TCPM and 4,4'4,″-TCPMOH are persistent and bioaccumulative.

Identifying unknown by-products in drinking water using comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry and in silico toxicity assessment

Improvements in extraction and detection technologies have increased our abilities to identify new disinfection by-products (DBPs) over the last 40 years. However, most previous studies combined DBP identification and measurement efforts with toxicology to address concerns on a few expected DBPs, making it difficult to better define the health risk from the individual DBPs. In this study, a nontargeted screening method involving comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS) combined with OECD QSAR Toolbox Ver. 3.2 was developed for identifying and prioritizing of volatile and semi-volatile DBPs in drinking water. The method was successfully applied to analyze DBPs formed during chlorination, chloramination or ozonation of the raw water. Over 500 compounds were tentatively identified in each sample, showing the superior performance of this analytical technique. A total of 170 volatile and semi-volatile DBPs representing fourteen chemical classes were then identified, according to the criteria that the DBP was presented in the duplicate treated samples. The genotoxicity and carcinogenicity of the DBPs were evaluated using Toolbox, and 58 DBPs were found to be actual or potential genotoxicants. The accuracy of the compound identification was determined by comparing 47 identified compounds with commercially available standards. About 90% (41 of the 47) of the compounds that were automatically identified using the library were correct. The results show that GC×GC-qMS coupled with a quantitative structure-activity relationship model is a powerful and fast nontargeted screening technique for compounds. The method and results provide us a new idea for identification and prioritization of DBPs.

A tiered, integrated biological and chemical monitoring framework for contaminants of emerging concern in aquatic ecosystems

The chemical-specific risk-based paradigm that informs monitoring and assessment of environmental contaminants does not apply well to the many thousands of new chemicals that are being introduced into ambient receiving waters. We propose a tiered framework that incorporates bioanalytical screening tools and diagnostic nontargeted chemical analysis to more effectively monitor for contaminants of emerging concern (CECs). The framework is based on a comprehensive battery of in vitro bioassays to first screen for a broad spectrum of CECs and nontargeted analytical methods to identify bioactive contaminants missed by the currently favored targeted analyses. Water quality managers in California have embraced this strategy with plans to further develop and test this framework in regional and statewide pilot studies on waterbodies that receive discharge from municipal wastewater treatment plants and stormwater runoff. In addition to directly informing decisions, the data obtained using this framework can be used to construct and validate models that better predict CEC occurrence and toxicity. The adaptive interplay among screening results, diagnostic assessment and predictive modeling will allow managers to make decisions based on the most current and relevant information, instead of extrapolating from parameters with questionable linkage to CEC impacts. Integr Environ Assess Manag 2016;12:540-547. © 2015 SETAC.

Extensive organohalogen contamination in wildlife from a site in the Yangtze River Delta

The environmental and human health concerns for organohalogen contaminants (OHCs) extend beyond the 23 persistent organic pollutants (POPs) regulated by the Stockholm Convention. The current, intense industrial production and use of chemicals in China and their bioaccumulation makes Chinese wildlife highly suitable for the assessment of legacy, novel and emerging environmental pollutants. In the present study, six species of amphibians, fish and birds were sampled from paddy fields in the Yangtze River Delta (YRD) were screened for OHCs. Some extensive contamination was found, both regarding number and concentrations of the analytes, among the species assessed. High concentrations of chlorinated paraffins were found in the snake, Short-tailed mamushi (range of 200-340 μg g(-)(1)lw), Peregrine falcon (8-59 μg g(-1)lw) and Asiatic toad (97 μg g(-)(1)lw). Novel contaminants and patterns were observed; octaCBs to decaCB made up 20% of the total polychlorinated biphenyls (PCBs) content in the samples and new OHCs, substituted with 5-8 chlorines, were found but are not yet structurally confirmed. In addition, Dechlorane 602 (DDC-DBF) and numerous other OHCs (DDTs, hexachlorocyclohexanes (HCHs), polybrominated diphenyl ethers (PBDEs), hexbromocyclododecane (HBCDD), chlordane, heptachlor, endosulfan and Mirex) were found in all species analyzed. These data show extensive chemical contamination of wildlife in the YRD with a suite of OHCs with both known and unknown toxicities, calling for further in-depth studies.

Meeting the European Commission performance criteria for the use of triple quadrupole GC-MS/MS as a confirmatory method for PCDD/Fs and dl-PCBs in food and feed samples

Until recently, European Union (EU) legislation required the use of high-resolution gas chromatography coupled to high-resolution mass spectrometry (HRGC-HRMS) based on magnetic sector analyzers as a standard approach for confirmatory analysis of dioxins (PCDDs) and furans (PCDFs) in feed and food. However, recent technological advances in MS instruments enabled other alternative analytical techniques to meet the same analytical criteria as those requested for HRGC-HRMS. In this sense, triple quadrupoles (GC-MS/MS) can be a realistic alternative for the analysis of dioxins. In this work, the performance of GC-MS/MS technology was evaluated against the criteria demanded by the EU for confirmatory analysis of dioxins and PCBs in food and feed. Thus, the study comprises a number of parameters including chromatographic separation, limit of quantification, linearity, repeatability, and ion ratio precision. Analyses of solvent standards as well as sample extracts (inter-calibration extracts and certified reference materials) were also considered within the scope of this study. Additionally, direct comparisons of the results obtained by GC-MS/MS with those from GC-HRMS were made. The results of this work suggested that GC-MS/MS was highly sensitive and selective for confirmatory analysis of PCDD/Fs and related compounds in food and feed samples and meets all the criteria requested by the European Commission.

Identification of ester metabolites from petroleum hydrocarbon biodegradation in groundwater using GC×GC-TOFMS

In an effort to understand the nature and toxicity of petroleum hydrocarbon degradation metabolites, 2-dimensional gas chromatography linked to a time-of-flight mass spectrometer (GC×GC-TOFMS) was used to conduct nontargeted analysis of the extracts of 61 groundwater samples collected from 10 fuel release sites. An unexpected result was the tentative identification of 197 unique esters. Although esters are known to be part of specific hydrocarbon degradative pathways, they are not commonly considered or evaluated in field studies of petroleum biodegradation. In addition to describing the compounds identified, the present study discusses the role for nontargeted analysis in environmental studies. Overall, the low toxicological profile of the identified esters, along with the limited potential for exposure, renders them unlikely to pose any significant health risk.

Halogenated Natural Products in Dolphins: Brain-Blubber Distribution and Comparison with Halogenated Flame Retardants

Halogenated natural products (MHC-1, TriBHD, TetraBHD, MeO-PBDEs, Q1, and related PMBPs) and halogenated flame retardants (PBDEs, HBB, Dec 602, Dec 603, and DP) in blubber and brain are reported from five Alboran Sea delphinids (Spain). Both HNPs and HFRs were detected in brain, implying that they are able to surpass the blood-brain barrier and reach the brain, which represents a new finding for some compounds, such as Q1 and PMBPs, MHC-1, TriBHD, TetraBHD, or Dec 603. Moreover, some compounds (TetraBHD, BDE-153, or HBB) presented higher levels in brain than in blubber. This study evidence the high concentrations of HNPs in the marine environment, especially in top predators. It shows the importance of further monitoring these natural compounds and evaluating their potential toxicity, when most studies focus on anthropogenic compounds only. While no bioaccumulation was found for ∑HNPs, ∑HFRs increased significantly with body size for both common and striped dolphins. Studies evaluating BBB permeation mechanisms of these compounds together with their potential neurotoxic effects in dolphins are recommended.

Identification strategies for flame retardants employing time-of-flight mass spectrometric detectors along with spectral and spectra-less databases

In the past, the preferred strategy for the identification of unknown compounds was to search in an appropriate mass spectral database for spectra obtained using either electron ionisation (GC-MS analyses) or collision-induced dissociation (LC-MS/MS analyses). Recently, an increase has been seen in the use of accurate mass instruments and spectra-less databases, based on monoisotopic accurate mass alone. In this article, we describe a systematic workflow for the screening and identification of new flame retardants. This approach utilises LC-quadrupole-time-of-flight MS and spectra-less databases based only on monoisotopic accurate mass for the identification of 'unknowns'. An in-house database was built, and the input parameters used in the data analysis process were optimised for flame retardant chemicals, so that it can be easily transferred to other laboratories. The procedure was successfully applied to dust, foam and textiles from car interiors and indoor consumer products. The developed method was demonstrated for the main new flame retardant present in Antiblaze V6 and for the three unreported reaction by-products/impurities present in the same technical mixture. Copyright © 2015 John Wiley & Sons, Ltd.

Identifying bioaccumulative halogenated organic compounds using a nontargeted analytical approach: seabirds as sentinels

Persistent organic pollutants (POPs) are typically monitored via targeted mass spectrometry, which potentially identifies only a fraction of the contaminants actually present in environmental samples. With new anthropogenic compounds continuously introduced to the environment, novel and proactive approaches that provide a comprehensive alternative to targeted methods are needed in order to more completely characterize the diversity of known and unknown compounds likely to cause adverse effects. Nontargeted mass spectrometry attempts to extensively screen for compounds, providing a feasible approach for identifying contaminants that warrant future monitoring. We employed a nontargeted analytical method using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS) to characterize halogenated organic compounds (HOCs) in California Black skimmer (Rynchops niger) eggs. Our study identified 111 HOCs; 84 of these compounds were regularly detected via targeted approaches, while 27 were classified as typically unmonitored or unknown. Typically unmonitored compounds of note in bird eggs included tris(4-chlorophenyl)methane (TCPM), tris(4-chlorophenyl)methanol (TCPMOH), triclosan, permethrin, heptachloro-1'-methyl-1,2'-bipyrrole (MBP), as well as four halogenated unknown compounds that could not be identified through database searching or the literature. The presence of these compounds in Black skimmer eggs suggests they are persistent, bioaccumulative, potentially biomagnifying, and maternally transferring. Our results highlight the utility and importance of employing nontargeted analytical tools to assess true contaminant burdens in organisms, as well as to demonstrate the value in using environmental sentinels to proactively identify novel contaminants.

A non-targeted gas chromatography/electron capture negative ionization mass spectrometry selected ion monitoring screening method for polyhalogenated compounds in environmental samples

RATIONALE

Many organohalogen compounds with adverse environmental properties have been detected in samples from marine ecosystems. Their quantitation is an important task in environmental analytical chemistry. However, the highly selective gas chromatography/mass spectrometry (GC/MS) selected ion monitoring (SIM) methods developed for this purpose only allow the detection of targeted compounds while unscreened compounds remain undiscovered. The detection of all polyhalogenated compounds in a sample requires the application of non-target methods.

METHODS

We present a simple quadrupole-based GC/ECNI-MS-SIM method in which the entire high mass range is screened in eight GC runs using three time windows. Recently developed in the GC/EI-MS mode, this approach has now been adapted to the more sensitive GC/ECNI-MS mode. With this method we analyzed a fraction of a dolphin blubber sample from Australia and a sponge sample from the Mediterranean Sea on polychlorinated and polybrominated compounds and compared the results with the corresponding GC/EI-MS measurements.

RESULTS

The non-targeted GC/ECNI-MS-SIM chromatograms were clearly structured and hardly showed co-elutions. Altogether, >400 polyhalogenated compounds were detected in both samples. Many of them originated from unknown compounds. Several new or scarcely analyzed compounds could be tentatively identified. Most of the compounds were not detected with the non-target GC/EI-MS-SIM approach (~150 compounds detected). We also developed a two-dimensional plot in which the mass of the monoisotopic peak was plotted over the GC retention time and which was helpful for the identification of isomers.

CONCLUSIONS

Since eight GC runs are required per sample, the method is not aimed for routine analysis. It is recommended as an initial screening method for the analysis of new sample matrices or samples from new regions. The non-targeted GC/ECNI-MS-SIM method benefits from the fact that it can be used with standard equipment.

Nontargeted biomonitoring of halogenated organic compounds in two ecotypes of bottlenose dolphins (Tursiops truncatus) from the Southern California Bight

Targeted environmental monitoring reveals contamination by known chemicals, but may exclude potentially pervasive but unknown compounds. Marine mammals are sentinels of persistent and bioaccumulative contaminants due to their longevity and high trophic position. Using nontargeted analysis, we constructed a mass spectral library of 327 persistent and bioaccumulative compounds identified in blubber from two ecotypes of common bottlenose dolphins (Tursiops truncatus) sampled in the Southern California Bight. This library of halogenated organic compounds (HOCs) consisted of 180 anthropogenic contaminants, 41 natural products, 4 with mixed sources, 8 with unknown sources, and 94 with partial structural characterization and unknown sources. The abundance of compounds whose structures could not be fully elucidated highlights the prevalence of undiscovered HOCs accumulating in marine food webs. Eighty-six percent of the identified compounds are not currently monitored, including 133 known anthropogenic chemicals. Compounds related to dichlorodiphenyltrichloroethane (DDT) were the most abundant. Natural products were, in some cases, detected at abundances similar to anthropogenic compounds. The profile of naturally occurring HOCs differed between ecotypes, suggesting more abundant offshore sources of these compounds. This nontargeted analytical framework provided a comprehensive list of HOCs that may be characteristic of the region, and its application within monitoring surveys may suggest new chemicals for evaluation.

Complexity of naturally produced polybrominated diphenyl ethers revealed via mass spectrometry

Polybrominated diphenyl ethers (PBDEs) are persistent and bioaccumulative anthropogenic and natural chemicals that are broadly distributed in the marine environment. PBDEs are potentially toxic due to inhibition of various mammalian signaling pathways and enzymatic reactions. PBDE isoforms vary in toxicity in accordance with structural differences, primarily in the number and pattern of hydroxyl moieties afforded upon a conserved core structure. Over four decades of isolation and discovery-based efforts have established an impressive repertoire of natural PBDEs. Based on our recent reports describing the bacterial biosyntheses of PBDEs, we predicted the presence of additional classes of PBDEs to those previously identified from marine sources. Using mass spectrometry and NMR spectroscopy, we now establish the existence of new structural classes of PBDEs in marine sponges. Our findings expand the chemical space explored by naturally produced PBDEs, which may inform future environmental toxicology studies. Furthermore, we provide evidence for iodinated PBDEs and direct attention toward the contribution of promiscuous halogenating enzymes in further expanding the diversity of these polyhalogenated marine natural products.

Complementary nontargeted and targeted mass spectrometry techniques to determine bioaccumulation of halogenated contaminants in freshwater species

Assessing the toxicological significance of complex environmental mixtures is challenging due to the large number of unidentified contaminants. Nontargeted analytical techniques may serve to identify bioaccumulative contaminants within complex contaminant mixtures without the use of analytical standards. This study exposed three freshwater organisms (Lumbriculus variegatus, Hexagenia spp., and Pimephales promelas) to a highly contaminated soil collected from a recycling plant fire site. Biota extracts were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and mass defect filtering to identify bioaccumulative halogenated contaminants. Specific bioaccumulative isomers were identified by comprehensive two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry (GCxGC-HRToF). Targeted analysis of mixed brominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PXDD/PXDFs, X = Br and Cl) was performed by atmospheric pressure gas chromatography tandem mass spectrometry (APGC-MS/MS). Relative sediment and biota instrument responses were used to estimate biota-sediment accumulation factors (BSAFs). Bioaccumulating contaminants varied among species and included polychlorinated naphthalenes (PCNs), polychlorinated dibenzofurans (PCDFs), chlorinated and mixed brominated/chlorinated anthracenes/phenanthrenes, and pyrenes/fluoranthenes (Cl-PAHs and X-PAHs, X = Br and Cl), as well as PXDD/PXDFs. Bioaccumulation potential among isomers also varied. This study demonstrates how complementary high-resolution mass spectrometry techniques identify persistent and bioaccumulative contaminants (and specific isomers) of environmental concern.

Identification of potential novel bioaccumulative and persistent chemicals in sediments from Ontario (Canada) using scripting approaches with GC×GC-TOF MS analysis

This work describes a single and fast approach using a filtering script as a means of prioritizing sample processing of data acquired by GC×GC-TOF MS for the identification of potentially novel persistent and bioaccumulative halogenated chemicals. The proposed script is based on the recognition of a generic halogenated isotope cluster pattern that allows for the simultaneous detection of chlorinated, brominated, or mixed halogen-substituted compounds in a single classification. Once developed, the script was applied to the identification of organohalogens in stream sediments collected across the southern region of Ontario (Canada). Classified peaks were first compared with available analytical standards and reference libraries to confirm the known chemicals. Unknown potential persistent organic pollutants (POPs) were evaluated for occurrence within the samples and high resolution mass spectrometry was used in order to identify some of the most prevalent compounds in the samples and resulting in the identification of three decachlorinated dechlorane analogs (C18H14Cl10), two undecachlorinated dechlorane species (C18H13Cl11), and a novel mixed chloro/bromo-carbazole (C12H5NCl2Br2) in a number of sediments analyzed. Relative peak abundances of these unknown halogenated compounds were in the same order of magnitude or slightly higher than levels observed for conventional POPs detected in the samples.

Concentrations of halogenated natural products versus PCB 153 in bivalves from the North and Baltic Seas

Different halogenated natural products (HNPs) have been reported to occur in marine wildlife, particularly from regions with comparably little contamination with anthropogenic pollutants. The North Sea and the Baltic Sea have been known as a marine site heavily polluted with organohalogen compounds, and especially with polychlorinated biphenyls (PCBs). In this study we wished to determine the current abundance of HNPs in comparison with 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153), i.e. the major PCB congener in marine biota. For this purpose, forty blue mussels (Mytilus edulis) and oysters (Crassostrea gigas) from seven sites were analyzed on HNPs and PCB 153. Most of the samples contained HNPs in the form of polyhalogenated 1'-methyl-1,2'-bipyrroles (PMBPs including Q1) and the mixed halogenated compound MHC-1. In addition we determined several polyhalogenated 1,1'-dimethyl-2,2'-bipyrroles (PDBPs), 2,3,4,5-tetrabromo-N-methylpyrrole and several novel homologs, as well as polybrominated N-methylindoles. The occurrence of these HNP groups were considerably different in the samples from different regions with varying sum concentrations up to 1930 μg/kg lipids in blue mussels from Heligoland (North Sea) and much lower concentrations in samples from the Baltic Sea (up to 13 μg/kg lipids). The concentrations of HNPs varied by two orders of magnitude, compared to a factor of 10 for PCB 153, suggesting that HNPs are more spatially (and perhaps temporally) variant than POPs. In the North Sea region Heligoland, HNPs were more abundant than PCB 153.

Using model-based screening to help discover unknown environmental contaminants

Of the tens of thousands of chemicals in use, only a small fraction have been analyzed in environmental samples. To effectively identify environmental contaminants, methods to prioritize chemicals for analytical method development are required. We used a high-throughput model of chemical emissions, fate, and bioaccumulation to identify chemicals likely to have high concentrations in specific environmental media, and we prioritized these for target analysis. This model-based screening was applied to 215 organosilicon chemicals culled from industrial chemical production statistics. The model-based screening prioritized several recognized organosilicon contaminants and generated hypotheses leading to the selection of three chemicals that have not previously been identified as potential environmental contaminants for target analysis. Trace analytical methods were developed, and the chemicals were analyzed in air, sewage sludge, and sediment. All three substances were found to be environmental contaminants. Phenyl-tris(trimethylsiloxy)silane was present in all samples analyzed, with concentrations of ∼50 pg m(-3) in Stockholm air and ∼0.5 ng g(-1) dw in sediment from the Stockholm archipelago. Tris(trifluoropropyl)trimethyl-cyclotrisiloxane and tetrakis(trifluoropropyl)tetramethyl-cyclotetrasiloxane were found in sediments from Lake Mjøsa at ∼1 ng g(-1) dw. The discovery of three novel environmental contaminants shows that models can be useful for prioritizing chemicals for exploratory assessment.

Strategies to characterize polar organic contamination in wastewater: exploring the capability of high resolution mass spectrometry

Wastewater effluents contain a multitude of organic contaminants and transformation products, which cannot be captured by target analysis alone. High accuracy, high resolution mass spectrometric data were explored with novel untargeted data processing approaches (enviMass, nontarget, and RMassBank) to complement an extensive target analysis in initial "all in one" measurements. On average 1.2% of the detected peaks from 10 Swiss wastewater treatment plant samples were assigned to target compounds, with 376 reference standards available. Corrosion inhibitors, artificial sweeteners, and pharmaceuticals exhibited the highest concentrations. After blank and noise subtraction, 70% of the peaks remained and were grouped into components; 20% of these components had adduct and/or isotope information available. An intensity-based prioritization revealed that only 4 targets were among the top 30 most intense peaks (negative mode), while 15 of these peaks contained sulfur. Of the 26 nontarget peaks, 7 were tentatively identified via suspect screening for sulfur-containing surfactants and one peak was identified and confirmed as 1,3-benzothiazole-2-sulfonate, an oxidation product of a vulcanization accelerator. High accuracy, high resolution data combined with tailor-made nontarget processing methods (all available online) provided vital information for the identification of a wider range of heteroatom-containing compounds in the environment.

Non-targeted analysis of petroleum metabolites in groundwater using GC×GC-TOFMS

Groundwater at fuel release sites often contains nonpolar hydrocarbons that originate from both the fuel release and other environmental sources, as well as polar metabolites of petroleum biodegradation. These compounds, along with other polar artifacts, can be quantified as "total petroleum hydrocarbons" using USEPA Methods 3510/8015B, unless a silica gel cleanup step is used to separate nonpolar hydrocarbons from polar compounds prior to analysis. Only a limited number of these metabolites have been identified by traditional GC-MS methods, because they are difficult to resolve using single-column configurations. Additionally, the targeted use of derivatization limits the detection of many potential metabolites of interest. The objective of this research was to develop a nontargeted GC×GC-TOFMS approach to characterize petroleum metabolites in environmental samples gathered from fuel release sites. The method tentatively identified more than 760 unique polar compounds, including acids/esters, alcohols, phenols, ketones, and aldehydes, from 22 groundwater samples collected at five sites. Standards for 28 polar compounds indicate that effective limits of quantitation for most of these compounds in the groundwater samples range from 1 to 11 μg/L.

Discovery and widespread occurrence of polyhalogenated 1,1'-dimethyl-2,2'-bipyrroles (PDBPs) in marine biota

Polyhalogenated 1,1'-dimethyl-2,2'-bipyrroles (PDBPs) are halogenated natural products (HNPs) previously shown to bioaccumulate in marine mammals and birds. Since their discovery in 1999, six hexahalogenated and a few lesser halogenated congeners have been identified in diverse marine mammal samples. Here we report the identification of 17 additional hexahalogenated PDBPs in the blubber extract of a humpback dolphin (Sousa chinensis) from Queensland, Australia. Thirteen of these new PDBPs were also detected in an Australian sea cucumber (Holothuria sp.). Additional samples were also tested positive on several new PDBPs, including an Australian venus tuskfish (Choerodon venustus) as well as a white whale (Delphinapterus leucas) and a sperm whale (Physeter macrocephalus) from the Northern Hemisphere. GC/ECNI-MS-SIM quantification of the molecular ions was carried out with the help of synthesized standards. The sum concentration of PDBPs was 1.1 mg/kg lipid in the humpback dolphin and 0.48 mg/kg lipid in the sea cucumber.

Environmental Mass Spectrometry in the North American Great Lakes Fish Monitoring and Surveillance Program

The Great Lakes Fish Monitoring and Surveillance Program (GLFMSP) has served to protect the Laurentian Great Lakes of North America for decades. Top predator fish from each lake are employed as bioindicators of chemical stressors within each lake. While a vast database has been created for legacy contaminants, such as polychlorinated biphenyls and organochlorine pesticides, a recent programmatic shift has transformed GLFMSP into a more proactive new chemical discovery/screening endeavour to capture the burden of more contemporary chemicals in the environment. The transition prompted the need for advanced instrumentation and the evaluation of mass spectrometric approaches beyond traditional electron capture detection and unit mass resolution mass spectrometers. Here the advances in detection methods are documented and the current direction of the program in creating a living database of anthropogenic chemicals affecting Great Lakes fish is highlighted.