Rapid activity-directed screening of estrogens by parallel coupling of liquid chromatography with a functional gene reporter assay and mass spectrometry

High-Efficiency Effect-Directed Analysis Leveraging Five High Level Advancements: A Critical Review

Organic contaminants are ubiquitous in the environment, with mounting evidence unequivocally connecting them to aquatic toxicity, illness, and increased mortality, underscoring their substantial impacts on ecological security and environmental health. The intricate composition of sample mixtures and uncertain physicochemical features of potential toxic substances pose challenges to identify key toxicants in environmental samples. Effect-directed analysis (EDA), establishing a connection between key toxicants found in environmental samples and associated hazards, enables the identification of toxicants that can streamline research efforts and inform management action. Nevertheless, the advancement of EDA is constrained by the following factors: inadequate extraction and fractionation of environmental samples, limited bioassay endpoints and unknown linkage to higher order impacts, limited coverage of chemical analysis (i.e., high-resolution mass spectrometry, HRMS), and lacking effective linkage between bioassays and chemical analysis. This review proposes five key advancements to enhance the efficiency of EDA in addressing these challenges: (1) multiple adsorbents for comprehensive coverage of chemical extraction, (2) high-resolution microfractionation and multidimensional fractionation for refined fractionation, (3) robust in vivo/vitro bioassays and omics, (4) high-performance configurations for HRMS analysis, and (5) chemical-, data-, and knowledge-driven approaches for streamlined toxicant identification and validation. We envision that future EDA will integrate big data and artificial intelligence based on the development of quantitative omics, cutting-edge multidimensional microfractionation, and ultraperformance MS to identify environmental hazard factors, serving for broader environmental governance.

Characterisation of (anti-)progestogenic and (anti-)androgenic activities in surface and wastewater using high resolution effectdirected analysis

The quality of surface waters is threatened by pollution with low concentrations of bioactive chemicals, among which those interfering with steroid hormone systems. Induced by reports of anti-progestogenic activity in surface waters, a two-year four-weekly survey of (anti-)progestogenic activity was performed at three surface water locations in the Netherlands that serve as abstraction points for the production of drinking water. As certain endogenous and synthetic progestogenic compounds are also potent (anti-)androgens, these activities were also investigated. Anti-progestogenic and anti-androgenic activities were detected in the majority of the monitoring samples, sometimes in concentrations exceeding effect-based trigger values, indicating the need for further research. To characterize the compounds responsible for the activities, a high resolution Effect-Directed Analysis (hr-EDA) panel was combined with PR and AR CALUX bioassays, performed in agonistic and antagonistic modes. The influent and effluent of a domestic wastewater treatment plant (WWTP) were included as effluent is a possible emission source of active compounds. As drivers for androgenic and progestogenic activities several native and synthetic steroid hormones were identified in the WWTP samples, namely androstenedione, testosterone, DHT, levonorgestrel and cyproterone acetate. The pesticides metolachlor and cyazofamid were identified as contributors to both the anti-progestogenic and anti-androgenic activities in surface water. In addition, epiconazole contributed to the anti-progestogenic activities in the rivers Rhine and Enclosed Meuse. This study showed the strength of hr-EDA for the identification of bioactive compounds in environmental samples and shed light on the drivers of (anti-)progestogenic and (anti-)androgenic activities in the aquatic environment.

patRoon: open source software platform for environmental mass spectrometry based non-target screening

Mass spectrometry based non-target analysis is increasingly adopted in environmental sciences to screen and identify numerous chemicals simultaneously in highly complex samples. However, current data processing software either lack functionality for environmental sciences, solve only part of the workflow, are not openly available and/or are restricted in input data formats. In this paper we present patRoon, a new R based open-source software platform, which provides comprehensive, fully tailored and straightforward non-target analysis workflows. This platform makes the use, evaluation and mixing of well-tested algorithms seamless by harmonizing various common (primarily open) software tools under a consistent interface. In addition, patRoon offers various functionality and strategies to simplify and perform automated processing of complex (environmental) data effectively. patRoon implements several effective optimization strategies to significantly reduce computational times. The ability of patRoon to perform time-efficient and automated non-target data annotation of environmental samples is demonstrated with a simple and reproducible workflow using open-access data of spiked samples from a drinking water treatment plant study. In addition, the ability to easily use, combine and evaluate different algorithms was demonstrated for three commonly used feature finding algorithms. This article, combined with already published works, demonstrate that patRoon helps make comprehensive (environmental) non-target analysis readily accessible to a wider community of researchers.

Receptor-based in vitro activities to assess human exposure to chemical mixtures and related health impacts

Humans are exposed to a large number of chemicals from sources such as the environment, food, and consumer products. There is growing concern that human exposure to chemical mixtures, especially during critical periods of development, increases the risk of adverse health effects in newborns or later in life. Historically, the one-chemical-at-a-time approach has been applied both for exposure assessment and hazard characterisation, leading to insufficient knowledge about human health effects caused by exposure to mixtures of chemicals that have the same target. To circumvent this challenge researchers can apply in vitro assays to analyse both exposure to and human health effects of chemical mixtures in biological samples. The advantages of using in vitro assays are: (i) that an integrated effect is measured, taking combined mixture effects into account and (ii) that in vitro assays can reduce complexity in identification of Chemicals of Emerging Concern (CECs) in human tissues. We have reviewed the state-of-the-art on the use of receptor-based in vitro assays to assess human exposure to chemical mixtures and related health impacts. A total of 43 studies were identified, in which endpoints for the arylhydrocarbon receptor (AhR), the estrogen receptor (ER), and the androgen receptor (AR) were used. The majority of studies reported biological activities that could be associated with breast cancer incidence, male reproductive health effects, developmental toxicities, human demographic characteristics or lifestyle factors such as dietary patterns. A few studies used the bioactivities to check the coverage of the chemical analyses of the human samples, whereas in vitro assays have so far not regularly been used for identifying CECs in human samples, but rather in environmental matrices or food packaging materials. A huge field of novel applications using receptor-based in vitro assays for mixture toxicity assessment on human samples and effect-directed analysis (EDA) using high resolution mass spectrometry (HRMS) for identification of toxic compounds waits for exploration. In the future this could lead to a paradigm shift in the way we unravel adverse human health effects caused by chemical mixtures.

High resolution effect-directed analysis of steroid hormone (ant)agonists in surface and wastewater quality monitoring

Monitoring of chemical water quality is extremely challenging due to the large variety of compounds and the presence of biologically active compounds with unknown chemical identity. Previously, we developed a high resolution Effect-Directed Analysis (EDA) platform that combines liquid chromatography with high resolution mass spectrometry and parallel bioassay detection. In this study, the platform is combined with CALUX bioassays for (anti)androgenic, estrogenic and glucocorticoid activities, and the performance of the platform is evaluated. It appeared to render very repeatable results, with high recoveries of spiked compounds and high consistency between the mass spectrometric and bioassay results. Application of the platform to wastewater treatment plant effluent and surface water samples led to the identification of several compounds contributing to the measured activities. Eventually, a workflow is proposed for the application of the platform in a routine monitoring context. The workflow divides the platform into four phases, of which one to all can be performed depending on the research question and the results obtained. This allows one to make a balance between the effort put into the platform and the certainty and depth by which active compounds will be identified. The EDA platform is a valuable tool to identify unknown bioactive compounds, both in an academic setting as in the context of legislative, governmental or routine monitoring.

Factors Affecting Sampling Strategies for Design of an Effects-Directed Analysis for Endocrine-Active Chemicals

Effects-directed analysis (EDA) is an important tool for identifying unknown bioactive components in a complex mixture. Such an analysis of endocrine-active chemicals (EACs) from water sources has promising regulatory implications but also unique logistical challenges. We propose a conceptual EDA (framework) based on a critical review of EDA literature and concentrations of common EACs in waste and surface waters. Required water volumes for identification of EACs under this EDA framework were estimated based on bioassay performance (in vitro and in vivo bioassays), limits of quantification by mass spectrometry (MS), and EAC water concentrations. Sample volumes for EDA across the EACs showed high variation in the bioassay detectors, with genistein, bisphenol A, and androstenedione requiring very high sample volumes and ethinylestradiol and 17β-trenbolone requiring low sample volumes. Sample volume based on the MS detector was far less variable across the EACs. The EDA framework equation was rearranged to calculate detector "thresholds," and these thresholds were compared with the literature EAC water concentrations to evaluate the feasibility of the EDA framework. In the majority of instances, feasibility of the EDA was limited by the bioassay, not MS detection. Mixed model analysis showed that the volumes required for a successful EDA were affected by the potentially responsible EAC, detection methods, and the water source type, with detection method having the greatest effect on the EDA of estrogens and androgens. The EDA framework, equation, and model we present provide a valuable tool for designing a successful EDA. Environ Toxicol Chem 2020;39:1309-1324. © 2020 SETAC.

Bioactivity Profiling of Small-Volume Samples by Nano Liquid Chromatography Coupled to Microarray Bioassaying Using High-Resolution Fractionation

High-throughput screening platforms for the identification of bioactive compounds in mixtures have become important tools in the drug discovery process. Miniaturization of such screening systems may overcome problems associated with small sample volumes and enhance throughput and sensitivity. Here we present a new screening platform, coined picofractionation analytics, which encompasses microarray bioassays and mass spectrometry (MS) of components from minute amounts of samples after their nano liquid chromatographic (nanoLC) separation. Herein, nanoLC was coupled to a low-volume liquid dispenser equipped with pressure-fed solenoid valves, enabling 50-nL volumes of column effluent (300 nL/min) to be discretely deposited on a glass slide. The resulting fractions were dried and subsequently bioassayed by sequential printing of nL-volumes of reagents on top of the spots. Unwanted evaporation of bioassay liquids was circumvented by employing mineral oil droplets. A fluorescence microscope was used for assay readout in kinetic mode. Bioassay data were correlated to MS data obtained using the same nanoLC conditions in order to assign bioactives. The platform provides the possibility of freely choosing a wide diversity of bioassay formats, including those requiring long incubation times. The new method was compared to a standard bioassay approach, and its applicability was demonstrated by screening plasmin inhibitors and fibrinolytic bioactives from mixtures of standards and snake venoms, revealing active peptides and coagulopathic proteases.

Compound Identification Using Liquid Chromatography and High-Resolution Noncontact Fraction Collection with a Solenoid Valve

We describe the development of a high-resolution, noncontact fraction collector for liquid chromatography (LC) separations, allowing high-resolution fractionation in high-density well plates. The device is based on a low-dead-volume solenoid valve operated at 1–30 Hz for accurate collection of fractions of equal volume. The solenoid valve was implemented in a modified autosampler resulting in the so-called FractioMate fractionator. The influence of the solenoid supply voltage on solvent release was determined and the effect of the frequency, flow rate, and mobile phase composition was studied. For this purpose, droplet release was visually assessed for a wide range of frequencies and flow rates, followed by quantitative evaluation of a selection of promising settings for highly accurate, repeatable, and stable fraction collection. The potential of the new fraction collector for LC-based bioactivity screening was demonstrated by fractionating the LC eluent of a mixture of estrogenic and androgenic compounds, and a surface water sample (blank and spiked with bioactives) combining mass spectrometric detection and two reporter gene assays for bioactivity detection of the fractions. Additionally, a mixture of two compounds was repeatedly LC separated and fractionated to assess the feasibility of the system for analyte isolation followed by nuclear magnetic resonance analysis.

The role of analytical chemistry in exposure science: Focus on the aquatic environment

Exposure science, in its broadest sense, studies the interactions between stressors (chemical, biological, and physical agents) and receptors (e.g. humans and other living organisms, and non-living items like buildings), together with the associated pathways and processes potentially leading to negative effects on human health and the environment. The aquatic environment may contain thousands of compounds, many of them still unknown, that can pose a risk to ecosystems and human health. Due to the unquestionable importance of the aquatic environment, one of the main challenges in the field of exposure science is the comprehensive characterization and evaluation of complex environmental mixtures beyond the classical/priority contaminants to new emerging contaminants. The role of advanced analytical chemistry to identify and quantify potential chemical risks, that might cause adverse effects to the aquatic environment, is essential. In this paper, we present the strategies and tools that analytical chemistry has nowadays, focused on chromatography hyphenated to (high-resolution) mass spectrometry because of its relevance in this field. Key issues, such as the application of effect direct analysis to reduce the complexity of the sample, the investigation of the huge number of transformation/degradation products that may be present in the aquatic environment, the analysis of urban wastewater as a source of valuable information on our lifestyle and substances we consumed and/or are exposed to, or the monitoring of drinking water, are discussed in this article. The trends and perspectives for the next few years are also highlighted, when it is expected that new developments and tools will allow a better knowledge of chemical composition in the aquatic environment. This will help regulatory authorities to protect water bodies and to advance towards improved regulations that enable practical and efficient abatements for environmental and public health protection.

Liquid chromatographic nanofractionation with parallel mass spectrometric detection for the screening of plasmin inhibitors and (metallo)proteinases in snake venoms

To better understand envenoming and to facilitate the development of new therapies for snakebite victims, rapid, sensitive, and robust methods for assessing the toxicity of individual venom proteins are required. Metalloproteinases comprise a major protein family responsible for many aspects of venom-induced haemotoxicity including coagulopathy, one of the most devastating effects of snake envenomation, and is characterized by fibrinogen depletion. Snake venoms are also known to contain anti-fibrinolytic agents with therapeutic potential, which makes them a good source of new plasmin inhibitors. The protease plasmin degrades fibrin clots, and changes in its activity can lead to life-threatening levels of fibrinolysis. Here, we present a methodology for the screening of plasmin inhibitors in snake venoms and the simultaneous assessment of general venom protease activity. Venom is first chromatographically separated followed by column effluent collection onto a 384-well plate using nanofractionation. Via a post-column split, mass spectrometry (MS) analysis of the effluent is performed in parallel. The nanofractionated venoms are exposed to a plasmin bioassay, and the resulting bioassay activity chromatograms are correlated to the MS data. To study observed proteolytic activity of venoms in more detail, venom fractions were exposed to variants of the plasmin bioassay in which the assay mixture was enriched with zinc or calcium ions, or the chelating agents EDTA or 1,10-phenanthroline were added. The plasmin activity screening system was applied to snake venoms and successfully detected compounds exhibiting antiplasmin (anti-fibrinolytic) activities in the venom of Daboia russelii, and metal-dependent proteases in the venom of Crotalus basiliscus. Graphical abstract ᅟ.

Steroid hormonal bioactivities, culprit natural and synthetic hormones and other emerging contaminants in waste water measured using bioassays and UPLC-tQ-MS

Emission of compounds with biological activities from waste water treatment plant (WWTP) effluents into surface waters is a topic of concern for ecology and drinking water quality. We investigated the occurrence of hormone-like activities in waste water sample extracts from four Dutch WWTPs and pursued to identify compounds responsible for them. To this aim, in vitro reporter gene bioassays for androgenic, anti-androgenic, estrogenic, glucocorticoid and progestogenic activity and a UPLC-tQ-MS target analysis method for 25 steroid hormones used in high volumes in pharmacy were applied. Principal component analysis of the data was performed to further characterize the detected activities and compounds. All five types of activities tested were observed in the WWTP samples. Androgenic and estrogenic activities were almost completely removed during WW treatment, anti-androgenic activity was only found in treated WW. Glucocorticoid and progestogenic activities persisted throughout the treatment. The androgenic activity in both influent could predominantly be attributed to the presence of androstenedione and testosterone. Anti-androgenic activity was explained by the presence of cyproterone acetate. The glucocorticoid activity in influent was fully explained by prednicarbate, triamcinolone acetonide, dexamethasone and amcinonide. In effluent however, detected hormones could only explain 10-32% of the activity, indicating the presence of unknown glucocorticoids or their metabolites in effluent. Progesterone and levonorgestrel could explain the observed progestogenic activity. The principle component analysis confirmed the way in which hormones fit in the spectrum of other emerging contaminants concerning occurrence and fate in WWTPs.

High-Throughput Effect-Directed Analysis Using Downscaled in Vitro Reporter Gene Assays To Identify Endocrine Disruptors in Surface Water

Effect-directed analysis (EDA) is a commonly used approach for effect-based identification of endocrine disruptive chemicals in complex (environmental) mixtures. However, for routine toxicity assessment of, for example, water samples, current EDA approaches are considered time-consuming and laborious. We achieved faster EDA and identification by downscaling of sensitive cell-based hormone reporter gene assays and increasing fractionation resolution to allow testing of smaller fractions with reduced complexity. The high-resolution EDA approach is demonstrated by analysis of four environmental passive sampler extracts. Downscaling of the assays to a 384-well format allowed analysis of 64 fractions in triplicate (or 192 fractions without technical replicates) without affecting sensitivity compared to the standard 96-well format. Through a parallel exposure method, agonistic and antagonistic androgen and estrogen receptor activity could be measured in a single experiment following a single fractionation. From 16 selected candidate compounds, identified through nontargeted analysis, 13 could be confirmed chemically and 10 were found to be biologically active, of which the most potent nonsteroidal estrogens were identified as oxybenzone and piperine. The increased fractionation resolution and the higher throughput that downscaling provides allow for future application in routine high-resolution screening of large numbers of samples in order to accelerate identification of (emerging) endocrine disruptors.

Recent trends in water analysis triggering future monitoring of organic micropollutants

Water analysis has been an important area since the beginning of analytical chemistry. The focus though has shifted substantially: from minerals and the main constituents of water in the time of Carl Remigius Fresenius to a multitude of, in particular, organic compounds at concentrations down to the sub-nanogram per liter level nowadays. This was possible only because of numerous innovations in instrumentation in recent decades, drivers of which are briefly discussed. In addition to the high demands on sensitivity, high throughput by automation and short analysis times are major requirements. In this article, some recent developments in the chemical analysis of organic micropollutants (OMPs) are presented. These include the analysis of priority pollutants in whole water samples, extension of the analytical window, in particular to encompass highly polar compounds, the trend toward more than one separation dimension before mass spectrometric detection, and ways of coping with unknown analytes by suspect and nontarget screening approaches involving high-resolution mass spectrometry. Furthermore, beyond gathering reliable concentration data for many OMPs, the question of the relevance of such data for the aquatic system under scrutiny is becoming ever more important. To that end, effect-based analytics can be used and may become part of future routine monitoring, mostly with a focus on adverse effects of OMPs in specific test systems mimicking environmental impacts. Despite advances in the field of water analysis in recent years, there are still many challenges for further analytical research. Graphical abstract Recent trends in water analysis of organic micropollutants that open new opportunities in future water monitoring. HRMS high-resolution mass spectrometry, PMOC persistent mobile organic compounds.

Nanofractionation Platform with Parallel Mass Spectrometry for Identification of CYP1A2 Inhibitors in Metabolic Mixtures

With early assessment of inhibitory properties of drug candidates and their circulating metabolites toward cytochrome P450 enzymes, drug attrition, especially later in the drug development process, can be decreased. Here we describe the development and validation of an at-line nanofractionation platform, which was applied for screening of CYP1A2 inhibitors in Phase I metabolic mixtures. With this platform, a metabolic mixture is separated by liquid chromatography (LC), followed by parallel nanofractionation on a microtiter well plate and mass spectrometry (MS) analysis. After solvent evaporation, all metabolites present in the nanofractionated mixture are assayed utilizing a fluorescence CYP1A2 inhibition bioassay performed on the plate. Next, a bioactivity chromatogram is constructed from the bioassay results. By peak shape and retention time correlation of the bioactivity peaks with the obtained MS data, CYP1A2-bioactive inhibiting metabolites can be identified. The method correctly evaluated the potency of five CYP1A2 inhibitors. Mixtures comprising potent inhibitors of CYP1A2 or in vitro-generated metabolites of ellipticine were evaluated for their inhibitory bioactivities. In both cases, good LC separation of all compounds was achieved and bioactivity data could be accurately correlated with the parallel recorded MS data. Generation and evaluation of Phase II metabolites of hydroxylated ellipticine was also pursued.

Bisphenol A alternatives in thermal paper from the Netherlands, Spain, Sweden and Norway. Screening and potential toxicity

Thermal paper contains potentially toxic additives, such as bisphenol A (BPA), as a common color developer. Because of its known endocrine disrupting effects, structural analogues to BPA, such as bisphenol S (BPS), D-8 and Pergafast 201, have been used as alternatives, but little is known about the presence and toxicological effects of alternatives other than BPS. In this study, thermal paper is screened by direct probe ambient mass spectrometry (rapid pre-screening method not requiring sample preparation) and by liquid chromatography (LC) with high resolution time-of flight (TOF-MS) mass spectrometry. Cash receipts and other thermal paper products (cinema tickets, boarding passes and luggage tags) were analyzed. Besides BPA and BPS, other developers only recently reported (Pergafast 201, D-8) or to the best of our knowledge not reported before (D-90, TGSA, BPS-MAE) were frequently found as well as some related unreported impurities (2,4-BPS that is a BPS related impurity and a TGSA related impurity). To gain some insight into the potential estrogenicity of the detected developers, a selection of extracts was further analyzed using a LC-nanofractionation platform in combination with cell-based bioassay testing. These preliminary results seems to indicate very low or absence of estrogenic activity for Pergafast 201, D-8, D-90, TGSA and BPS-MAE in comparison to BPA and BPS, although further dose-response tests with authentic standards are required to confirm these results. Compounds for which standards were available were also tested for developmental toxicity and neurotoxicity using zebrafish (Danio rerio) embryos. TGSA and D-8 induced similar teratogenic effects as BPA in zebrafish embryos. BPS and 2,4-BPS did not induce any developmental effects but 2,4-BPS did alter the locomotor activity at the tested concentration. Our findings suggest that the alternatives used as alternatives to BPA (except BPS) might not be estrogenic. However, TGSA and D-8 showed abnormal developmental effects similar to BPA.

Unprecedented sensitivity of the planar yeast estrogen screen by using a spray-on technology

The planar yeast estrogen screen (p-YES) can serve as a highly valuable and sensitive screening tool for the detection of estrogenic compounds in various sample matrices such as water and wastewater, personal care products and foodstuff. The method combines the separation of sample constituents by thin layer chromatography with the direct detection of estrogenic compounds on the surface of the HPTLC-plate. The previous protocol using the immersion of a normal phase silica HPTLC-plate in a cell suspension for bio-autography resulted in blurred signals due to the accelerated diffusion of compounds on the wet surface of the HPTLC-plate. Here, the application of the yeast cells by spraying on the surface of the HPTLC-plate is described as an alternative approach. The presented method for the hyphenation of normal phase thin layer chromatography with a yeast estrogen screen results in much sharper signals compared to reports in previous publications. Satisfying results were achieved using cultures with cell densities of 1000 FAU. Due to the reduced signal broadening, lower limits of quantification for estrogenic compounds were achieved (Estrone (E1)=2pg/zone, 17β-estradiol (E2)=0.5pg/zone, 17α-ethinylestradiol (EE2)=0.5pg/zone and Estriol (E3)=20pg/zone). As demonstrated, it is possible to characterize profiles of estrogenic activity of wastewater samples with high quality and reproducibility. The improved sensitivity opens the stage for applications using native samples from waste- or even surface water directly applied on HPTLC-plates without the need for prior sample treatment by e.g. solid phase extraction.

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.

Toward Streamlined Identification of Dioxin-like Compounds in Environmental Samples through Integration of Suspension Bioassay

Effect-directed analysis (EDA) is a powerful strategy to identify biologically active compounds in environmental samples. However, in current EDA studies, fractionation and handling procedures are laborious, consist of multiple evaporation steps, and thus bear the risk of contamination and decreased recoveries of the target compounds. The low resulting throughput has been one of the major bottlenecks of EDA. Here, we propose a high-throughput EDA (HT-EDA) work-flow combining reversed phase high-performance liquid chromatography fractionation of samples into 96-well microplates, followed by toxicity assessment in the micro-EROD bioassay with the wild-type rat hepatoma H4IIE cells, and chemical analysis of bioactive fractions. The approach was evaluated using single substances, binary mixtures, and extracts of sediment samples collected at the Three Gorges Reservoir, Yangtze River, China, as well as the rivers Rhine and Elbe, Germany. Selected bioactive fractions were analyzed by highly sensitive gas chromatography-atmospheric pressure laser ionization-time-of-flight-mass spectrometry. In addition, we optimized the work-flow by seeding previously adapted suspension-cultured H4IIE cells directly into the microplate used for fractionation, which makes any transfers of fractionated samples unnecessary. The proposed HT-EDA work-flow simplifies the procedure for wider application in ecotoxicology and environmental routine programs.

Toxicity profiling of marine surface sediments: A case study using rapid screening bioassays of exhaustive total extracts, elutriates and passive sampler extracts

This study was carried out in the framework of the ICON project (Integrated Assessment of Contaminant Impacts on the North Sea) (Hylland et al., 2015) and aimed (1) to evaluate the toxicity of marine sediments using a battery of rapid toxicity bioassays, and; (2) to explore the applicability and data interpretation of in vitro toxicity profiling of sediment extracts obtained from ex situ passive sampling. Sediment samples were collected at 12 selected (estuarine, coastal, offshore) sites in the North Sea, Icelandic waters (as reference sites), south-western Baltic Sea and western Mediterranean during autumn 2008. Organic extracts using a mild non-destructive clean-up procedure were prepared from total sediment and silicone passive samplers and tested with five in vitro bioassays: DR-Luc bioassay, ER-Luc bioassay, AR-EcoScreen bioassay, transthyretin (TTR) binding assay, and Vibrio fischeri bioluminescence bioassay. In vitro toxicity profiling of total sediment and silicone passive sampler extracts showed the presence of multiple organic contaminations by arylhydrocarbon receptor agonists (e.g. polycyclic aromatic hydrocarbons) and endocrine-active compounds, as well as non-specific toxicity caused by organic contaminants, at virtually all sampling sites. In vitro responses to total sediment extracts from coastal/estuarine sites were significantly different from those in offshore sites (p < 0.05). Several bioassays of passive sampler extracts showed highest activity in some offshore sediment samples. Impact on embryogenesis success and larval growth in undiluted sediment elutriates was shown at some sites using the in vivo sea urchin embryo test. The observed toxicity profiles could only partially be explained by the chemical target analysis, indicating the presence of unknown or unanalysed biologically-active compounds in the sediments. In vitro bioassay testing with silicone passive sampler extracts of sediments is a promising tool to assess the toxic potency of the bioavailable fraction of hydrophobic sediment contaminants, but further work will be needed before it can be routinely applied for sediment quality assessment.

Trends in the application of high-resolution mass spectrometry for human biomonitoring: An analytical primer to studying the environmental chemical space of the human exposome

Global profiling of xenobiotics in human matrices in an untargeted mode is gaining attention for studying the environmental chemical space of the human exposome. Defined as the study of a comprehensive inclusion of environmental influences and associated biological responses, human exposome science is currently evolving out of the metabolomics science. In analogy to the latter, the development and applications of high resolution mass spectrometry (HRMS) has shown potential and promise to greatly expand our ability to capture the broad spectrum of environmental chemicals in exposome studies. HRMS can perform both untargeted and targeted analysis because of its capability of full- and/or tandem-mass spectrum acquisition at high mass accuracy with good sensitivity. The collected data from target, suspect and non-target screening can be used not only for the identification of environmental chemical contaminants in human matrices prospectively but also retrospectively. This review covers recent trends and advances in this field. We focus on advances and applications of HRMS in human biomonitoring studies, and data acquisition and mining. The acquired insights provide stepping stones to improve understanding of the human exposome by applying HRMS, and the challenges and prospects for future research.

Validation of a two-dimensional liquid chromatography method for quality control testing of pharmaceutical materials

Despite the advantages of 2D-LC, there is currently little to no work in demonstrating the suitability of these 2D-LC methods for use in a quality control (QC) environment for good manufacturing practice (GMP) tests. This lack of information becomes more critical as the availability of commercial 2D-LC instrumentation has significantly increased, and more testing facilities begin to acquire these 2D-LC capabilities. It is increasingly important that the transferability of developed 2D-LC methods be assessed in terms of reproducibility, robustness and performance across different laboratories worldwide. The work presented here focuses on the evaluation of a heart-cutting 2D-LC method used for the analysis of a pharmaceutical material, where a key, co-eluting impurity in the first dimension (¹D) is resolved from the main peak and analyzed in the second dimension (²D). A design-of-experiments (DOE) approach was taken in the collection of the data, and the results were then modeled in order to evaluate method robustness using statistical modeling software. This quality by design (QBD) approach gives a deeper understanding of the impact of these 2D-LC critical method attributes (CMAs) and how they affect overall method performance. Although there are multiple parameters that may be critical from method development point of view, a special focus of this work is devoted towards evaluation of unique 2D-LC critical method attributes from method validation perspective that transcend conventional method development and validation. The 2D-LC method attributes are evaluated for their recovery, peak shape, and resolution of the two co-eluting compounds in question on the ²D. In the method, linearity, accuracy, precision, repeatability, and sensitivity are assessed along with day-to-day, analyst-to-analyst, and lab-to-lab (instrument-to-instrument) assessments. The results of this validation study demonstrate that the 2D-LC method is accurate, sensitive, and robust and is ultimately suitable for QC testing with good method transferability.

Highly Selective Screening of Estrogenic Compounds in Consumer-Electronics Plastics by Liquid Chromatography in Parallel Combined with Nanofractionation-Bioactivity Detection and Mass Spectrometry

The chemical safety of consumer products is an issue of emerging concern. Plastics are widely used, e.g. as casings of consumer electronics (TVs, computers, routers, etc.), which are present in houses and offices in continuously increasing numbers. In this study, we investigate the estrogenic activity of components of plastics coming from electronics' casings. A recently developed fractionation platform for effect-directed analysis (EDA) was used. This platform combines reversed-phase liquid chromatography in parallel with bioassay detection via nanofractionation and with online high-resolution time-of-flight mass spectrometry (TOFMS) for the identification of bioactives. Four out of eight of the analyzed plastics samples showed the presence of estrogenic compounds. Based on the MS results these were assigned to bisphenol A (BPA), 2,4-di-tert-butylphenol, and a possible bisphenol A analog. All samples contained flame retardants, but these did not show any estrogenicity. The observed BPA, however, could be an impurity of tetrabromo-BPA (TBBPA) or TBBPA-based flame retardants. Due to the plausible migration of additives from plastics into the environment, plastics from consumer electronics likely constitute a source of estrogenic compound contamination in the indoor environment.