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

Urban and agricultural influences on the coastal dissolved organic matter pool in the Algoa Bay estuaries

While anthropogenic pollution is a major threat to aquatic ecosystem health, our knowledge of the presence of xenobiotics in coastal Dissolved Organic Matter (DOM) is still relatively poor. This is especially true for water bodies in the Global South with limited information gained mostly from targeted studies that rely on comparison with authentic standards. In recent years, non-targeted tandem mass spectrometry has emerged as a powerful tool to collectively detect and identify pollutants and biogenic DOM components in the environment, but this approach has yet to be widely utilized for monitoring ecologically important aquatic systems. In this study we compared the DOM composition of Algoa Bay, Eastern Cape, South Africa, and its two estuaries. The Swartkops Estuary is highly urbanized and severely impacted by anthropogenic pollution, while the Sundays Estuary is impacted by commercial agriculture in its catchment. We employed solid-phase extraction followed by liquid chromatography tandem mass spectrometry to annotate more than 200 pharmaceuticals, pesticides, urban xenobiotics, and natural products based on spectral matching. The identification with authentic standards confirmed the presence of methamphetamine, carbamazepine, sulfamethoxazole, N-acetylsulfamethoxazole, imazapyr, caffeine and hexa(methoxymethyl)melamine, and allowed semi-quantitative estimations for annotated xenobiotics. The Swartkops Estuary DOM composition was strongly impacted by features annotated as urban pollutants including pharmaceuticals such as melamines and antiretrovirals. By contrast, the Sundays Estuary exhibited significant enrichment of molecules annotated as agrochemicals widely used in the citrus farming industry, with predicted concentrations for some of them exceeding predicted no-effect concentrations. This study provides new insight into anthropogenic impact on the Algoa Bay system and demonstrates the utility of non-targeted tandem mass spectrometry as a sensitive tool for assessing the health of ecologically important coastal ecosystems and will serve as a valuable foundation for strategizing long-term monitoring efforts.

Aflatoxins: Occurrence, biosynthesis, mechanism of action and effects, conventional/emerging detection techniques

Aflatoxins (AFs) are toxic secondary metabolites prevalent in various food and agricultural products, posing significant challenges to global food safety. The detection and quantification of AFs through high-precision analytical techniques are crucial in mitigating AF contamination levels and associated health risks. Variousmethods,including conventional and emerging techniques, have been developed for detecting and quantifyingAFsinfood samples. This review provides an in-depth analysis of the global occurrence of AF in food commodities, covering their biosynthesis, mode of action, and effects on humans and animals. Additionally, the review discusses different conventional strategies, including chromatographic and immunochemical approaches, for AF quantification and identification in food samples. Furthermore, emerging AF detection strategies, such as solid-state gas sensors and electronic nose technologies, along with their applications, limitations, and future perspectives, were reviewed. Sample purification, along with their respective advantages and limitations, are also discussed herein.

Unraveling the chemical fingerprint of the Miami River sources: Insights from high-resolution mass spectrometry and nontarget analysis

This study investigated the chemical composition of waters in the heavily urbanized and historically polluted Miami River, Florida. The goal was to assess the different water sources and anthropogenic influence in this managed area using nontarget analysis (NTA) combined with high-resolution mass spectrometry (HRMS). Surface water samples were collected from 10 sites during five sampling events in the wet season of 2021 and 2022. The HRMS data was processed using Compound Discoverer™ version 3.3, and the results were analyzed using techniques including Principal Component Analysis and Kendrick Mass Defect plots. Results showed a gradient change in the chemical composition from the Everglades to Biscayne Bay endmembers. The Seybold Canal, an adjacent canal, was consistently identified as a unique source of contaminants, contributing its own specific set of tracers. Increased presence and intensity of organic contaminants along the waterway was observed, indicating significant anthropogenic influence in the area. The NTA and post-processing were evaluated for reproducibility, demonstrating robustness with a 71.2% average reproducibility for compounds detected in 3 out of 5 sampling trips. A detection frequency of 80% (4 out of 5) was the set criterion for detected compounds suggested as tracers. To prioritize samples, hierarchical cluster analysis was employed, and potential tracers for each water source were determined. Tracers included natural products and agricultural herbicides and insecticides for the Everglades, anthropogenic contaminants for the Seybold Canal, and a lack of unique tracers for Biscayne Bay. Additionally, urban-influenced contaminants such as flame retardants, insect repellents, pharmaceuticals, and non-agricultural herbicides were identified along the river. This study highlights the impact of human activities on the Miami River and demonstrates the effectiveness of NTA in differentiating and tracking water sources. The results emphasize the importance of reproducibility in NTA and provide guidance on implementing monitoring strategies by prioritizing samples based on chemical compositions.

Transformation products of antibacterial drugs in environmental water: Identification approaches based on liquid chromatography-high resolution mass spectrometry

In recent years, the presence of antibiotics in the aquatic environment has caused increasing concern for the possible consequences on human health and ecosystems, including the development of antibiotic-resistant bacteria. However, once antibiotics enter the environment, mainly through hospital and municipal discharges and the effluents of wastewater treatment plants, they can be subject to transformation reactions, driven by both biotic (e.g. microorganism and mammalian metabolisms) and abiotic factors (e.g. oxidation, photodegradation, and hydrolysis). The resulting transformation products (TPs) can be less or more active than their parent compounds, therefore the inclusion of TPs in monitoring programs should be mandatory. However, only the reference standards of a few known TPs are available, whereas many other TPs are still unknown, due to the high diversity of possible transformation reactions in the environment. Modern high-resolution mass spectrometry (HRMS) instrumentation is now ready to tackle this problem through suspect and untargeted screening approaches. However, for handling the large amount of data typically encountered in the analysis of environmental samples, these approaches also require suitable processing workflows and accurate tandem mass spectra interpretation. The compilation of a suspect list containing the possible monoisotopic masses of TPs retrieved from the literature and/or from laboratory simulated degradation experiments showed unique advantages. However, the employment of in silico prediction tools could improve the identification reliability. In this review, the most recent strategies relying on liquid chromatography-HRMS for the analysis of environmental TPs of the main antibiotic classes were examined, whereas TPs formed during water treatments or disinfection were not included.

Is Nontarget Analysis Ready for Regulatory Application? Influence of Peak-Picking Algorithms on Data Analysis

The use of peak-picking algorithms is an essential step in all nontarget analysis (NTA) workflows. However, algorithm choice may influence reliability and reproducibility of results. Using a real-world data set, the aim of this study was to investigate how different peak-picking algorithms influence NTA results when exploring temporal and/or spatial trends. For this, drinking water catchment monitoring data, using passive samplers collected twice per year across Southeast Queensland, Australia (n = 18 sites) between 2014 and 2019, was investigated. Data were acquired using liquid chromatography coupled to high-resolution mass spectrometry. Peak picking was performed using five different programs/algorithms (SCIEX OS, MSDial, self-adjusting-feature-detection, two algorithms within MarkerView), keeping parameters identical whenever possible. The resulting feature lists revealed low overlap: 7.2% of features were picked by >3 algorithms, while 74% of features were only picked by a single algorithm. Trend evaluation of the data, using principal component analysis, showed significant variability between the approaches, with only one temporal and no spatial trend being identified by all algorithms. Manual evaluation of features of interest (p-value <0.01, log fold change >2) for one sampling site revealed high rates of incorrectly picked peaks (>70%) for three algorithms. Lower rates (<30%) were observed for the other algorithms, but with the caveat of not successfully picking all internal standards used as quality control. The choice is therefore currently between comprehensive and strict peak picking, either resulting in increased noise or missed peaks, respectively. Reproducibility of NTA results remains challenging when applied for regulatory frameworks.

Effect-Directed Analysis Combined with Nontarget Screening to Identify Unmonitored Toxic Substances in the Environment

Effect-directed analysis (EDA) combined with nontarget screening (NTS) has established a valuable tool for the identification of unmonitored toxic substances in environmental samples. It consists of three main steps: (1) highly potent fraction identification, (2) toxicant candidate selection, and (3) major toxicant identification. Here, we discuss the methodology, current status, limitations, and future challenges of EDA combined with NTS. This method has been applied successfully to various environmental samples, such as sediments, wastewater treatment plant effluents, and biota. We present several case studies and highlight key results. EDA has undergone significant technological advancements in the past 20 years, with the establishment of its key components: target chemical analysis, bioassays, fractionation, NTS, and data processing. However, it has not been incorporated widely into environmental monitoring programs. We provide suggestions for the application of EDA combined with NTS in environmental monitoring programs and management, with the identification of further research needs.

Machine Learning-Based Hazard-Driven Prioritization of Features in Nontarget Screening of Environmental High-Resolution Mass Spectrometry Data

Nontarget high-resolution mass spectrometry screening (NTS HRMS/MS) can detect thousands of organic substances in environmental samples. However, new strategies are needed to focus time-intensive identification efforts on features with the highest potential to cause adverse effects instead of the most abundant ones. To address this challenge, we developed MLinvitroTox, a machine learning framework that uses molecular fingerprints derived from fragmentation spectra (MS2) for a rapid classification of thousands of unidentified HRMS/MS features as toxic/nontoxic based on nearly 400 target-specific and over 100 cytotoxic endpoints from ToxCast/Tox21. Model development results demonstrated that using customized molecular fingerprints and models, over a quarter of toxic endpoints and the majority of the associated mechanistic targets could be accurately predicted with sensitivities exceeding 0.95. Notably, SIRIUS molecular fingerprints and xboost (Extreme Gradient Boosting) models with SMOTE (Synthetic Minority Oversampling Technique) for handling data imbalance were a universally successful and robust modeling configuration. Validation of MLinvitroTox on MassBank spectra showed that toxicity could be predicted from molecular fingerprints derived from MS2 with an average balanced accuracy of 0.75. By applying MLinvitroTox to environmental HRMS/MS data, we confirmed the experimental results obtained with target analysis and narrowed the analytical focus from tens of thousands of detected signals to 783 features linked to potential toxicity, including 109 spectral matches and 30 compounds with confirmed toxic activity.

Determination of several PFAS groups in food packaging material from fast-food restaurants in France

Per- and polyfluoroalkylated substances (PFAS) are a large group of toxic compounds which have been widely used in industrial and consumer applications, from where they can migrate into the environment. They can pose a risk to human health because they have been associated with several diseases. To obtain more information on the risk of PFAS in fast food packaging materials, several PFAS (perfluorocarboxylic acids or PFCAs (n = 16), perfluorosulfonic acids or PFSAs (n = 14), and a miscellaneous group constituted by sulfonamides (n = 5) and fluorotelomer phosphate esters or PAPs (n = 5)) were quantified in food contact materials (FCMs) from fast-food restaurants in France. Perfluorohexanoic acid (PFHxA), 6:2 fluorotelomer sulfonic acid (6:2 FTS) and 6:2/6:2 fluorotelomer phosphate diester (6:2/6:2 diPAP) were detected in all samples. PFCAs with shorter chain lengths (C4-C6) showed the highest concentrations compared to median (C7-C10) and longer chain length PFCAs (C11-C18). However, they had lower detection frequencies (DFs) (except for PFHxA, DF = 100%) with values of 36 and 34% for C4 and C5 PFCAs, respectively. The DF of longer chain length PFCAs was higher, especially those of the median chain length PFCAs (C8-C10, with DF = 79-98%). Analytes from the PFSA group with high DFs (70-98%) were perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS, linear and branched) and 10:2 fluorotelomer sulfonic acid (10:2 FTS), with concentrations similar to some analytes from the PFCA group. 4:2 Fluorotelomer phosphate monoester (4:2 mPAP), 8:2 fluorotelomer phosphate monoester (8:2 mPAP) and 8:2/8:2 fluorotelomer phosphate diester (8:2/8:2 diPAP) were found with the highest concentrations (<0.006-42.7 ng g-1, <0.001-2.7 ng g-1 and <0.001-287 ng g-1, respectively) and the highest DFs (ranged 68-94%). Some correlations between analytes were found, indicating similar degradation routes or a common origin.

Critical Assessment of the Chemical Space Covered by LC-HRMS Non-Targeted Analysis

Non-targeted analysis (NTA) has emerged as a valuable approach for the comprehensive monitoring of chemicals of emerging concern (CECs) in the exposome. The NTA approach can theoretically identify compounds with diverse physicochemical properties and sources. Even though they are generic and have a wide scope, non-targeted analysis methods have been shown to have limitations in terms of their coverage of the chemical space, as the number of identified chemicals in each sample is very low (e.g., ≤5%). Investigating the chemical space that is covered by each NTA assay is crucial for understanding the limitations and challenges associated with the workflow, from the experimental methods to the data acquisition and data processing techniques. In this review, we examined recent NTA studies published between 2017 and 2023 that employed liquid chromatography-high-resolution mass spectrometry. The parameters used in each study were documented, and the reported chemicals at confidence levels 1 and 2 were retrieved. The chosen experimental setups and the quality of the reporting were critically evaluated and discussed. Our findings reveal that only around 2% of the estimated chemical space was covered by the NTA studies investigated for this review. Little to no trend was found between the experimental setup and the observed coverage due to the generic and wide scope of the NTA studies. The limited coverage of the chemical space by the reviewed NTA studies highlights the necessity for a more comprehensive approach in the experimental and data processing setups in order to enable the exploration of a broader range of chemical space, with the ultimate goal of protecting human and environmental health. Recommendations for further exploring a wider range of the chemical space are given.

Analysis of environmental pollutants using ion chromatography coupled with mass spectrometry: A review

The rise of emerging pollutants in the current environment and requirements of trace analysis in complex substrates pose challenges to modern analytical techniques. Ion chromatography coupled with mass spectrometry (IC-MS) is the preferred tool for analyzing emerging pollutants due to its excellent separation ability for polar and ionic compounds with small molecular weight and high detection sensitivity and selectivity. This paper reviews the progress of sample preparation and ion-exchange IC-MS methods in the analysis of several major categories of environmental polar and ionic pollutants including perchlorate, inorganic and organic phosphorus compounds, metalloids and heavy metals, polar pesticides, and disinfection by-products in past two decades. The comparison of various methods to reduce the influence of matrix effect and improve the accuracy and sensitivity of analysis are emphasized throughout the process from sample preparation to instrumental analysis. Furthermore, the human health risks of these pollutants in the environment with natural concentration levels in different environmental medias are also briefly discussed to raise public attention. Finally, the future challenges of IC-MS for analysis of environmental pollutants are briefly discussed.

Efficient Validation Strategies in Environmental Analytical Chemistry: A Focus on Organic Micropollutants in Water Samples

This article critically reviews analytical method validation and quality control applied to the environmental chemistry field. The review focuses on the determination of organic micropollutants (OMPs), specifically emerging contaminants and pesticides, in the aquatic environment. The analytical technique considered is (gas and liquid) chromatography coupled to mass spectrometry (MS), including high-resolution MS for wide-scope screening purposes. An analysis of current research practices outlined in the literature has been performed, and key issues and analytical challenges are identified and critically discussed. It is worth emphasizing the lack of specific guidelines applied to environmental analytical chemistry and the minimal regulation of OMPs in waters, which greatly affect method development and performance, requirements for method validation, and the subsequent application to samples. Finally, a proposal is made for method validation and data reporting, which can be understood as starting points for further discussion with specialists in environmental analytical chemistry.

Risk assessment of chemicals and their mixtures are hindered by scarcity and inconsistencies between different environmental exposure limits

In chemical risk assessment, measured or modelled environmental concentrations are compared to environmental exposure limits (EELs), such as Predicted No Effect Concentrations (PNECs) or hazardous concentrations for 5% of species (HC05s) derived from species sensitivity distributions (SSDs). However, for many chemicals the EELs include large uncertainties or, in the worst case, the necessary data for their estimation are completely missing. This makes the assessment of chemical risks and any subsequent implementation of management strategies challenging. In this study we analyzed the uncertainty of EELs and its impact on chemical risk assessment. First, we compared three individual EEL datasets, two primarily based on experimental data and one based on computational predictions. The comparison demonstrates large disagreements between EEL data sources, with experimentally derived EELs differing by more than seven orders of magnitude. In a case-study, based on the predicted emissions of 2005 chemicals, we showed that these uncertainties lead to significantly different risk assessment outcomes, including large differences in the magnitude of the total risk, risk driver identification, and the ranking of use categories as risk contributors. We also show that the large data-gaps in EEL datasets cannot be covered by commonly used computational approaches (QSARs). We conclude that an expanded framework for interpreting risk characterization outcomes is needed. We also argue that the large data-gaps present in ecotoxicological data need to be addressed in order to achieve the European zero pollution vision as the growing emphasis on ambient exposures will further increase the demand for accurate and well-established EELs.

InSpectra - A platform for identifying emerging chemical threats

Non-target analysis (NTA) employing high-resolution mass spectrometry (HRMS) coupled with liquid chromatography is increasingly being used to identify chemicals of biological relevance. HRMS datasets are large and complex making the identification of potentially relevant chemicals extremely challenging. As they are recorded in vendor-specific formats, interpreting them is often reliant on vendor-specific software that may not accommodate advancements in data processing. Here we present InSpectra, a vendor independent automated platform for the systematic detection of newly identified emerging chemical threats. InSpectra is web-based, open-source/access and modular providing highly flexible and extensible NTA and suspect screening workflows. As a cloud-based platform, InSpectra exploits parallel computing and big data archiving capabilities with a focus for sharing and community curation of HRMS data. InSpectra offers a reproducible and transparent approach for the identification, tracking and prioritisation of emerging chemical threats.

Responses of Aroma Related Metabolic Attributes of Opisthopappus longilobus Flowers to Environmental Changes

Opisthopappus longilobus (Opisthopappus) and its descendant species, Opisthopappus taihangensis, commonly thrive on the Taihang Mountains of China. Being typical cliff plants, both O. longilobus and O. taihangensis release unique aromatics. To determine the potential differentiation and environmental response patterns, comparative metabolic analysis was performed on O. longilobus wild flower (CLW), O. longilobus transplant flower (CLT), and O. taihangensis wild flower (TH) groups. Significant differences in the metabolic profiles were found, not within O. longilobus, but between O. longilobus and O. taihangensis flowers. Within these metabolites, twenty-eight substances related to the scents were obtained (one alkene, two aldehydes, three esters, eight phenols, three acids, three ketones, three alcohols, and five flavonoids), of which eugenol and chlorogenic were the primary aromatic molecules and enriched in the phenylpropane pathway. Network analysis showed that close relationships occurred among identified aromatic substances. The variation coefficient (CV) of aromatic metabolites in O. longilobus was lower than O. taihangensis. The aromatic related compounds were significantly correlated with the lowest temperatures in October and in December of the sampled sites. The results indicated that phenylpropane, particularly eugenol and chlorogenic, played important roles in the responses of O. longilobus species to environmental changes.

Biotic transformation products of sulfonamides in environmental water samples: High-resolution mass spectrometry-based tentative identification by a suspect screening approach

The presence of pharmaceuticals in the aquatic environment is mainly due to their release from the effluents of the wastewater treatment plants (WWTPs), which are unable to completely remove them and their transformation products (TPs). Sulfonamides (SAs) are a synthetic antibacterial class used for the treatment of both human and animal infections; they have often been reported in surface water, thus contributing to the antibiotic resistance emergency. Monitoring SA TPs should be important as well because they could still exert some pharmaceutical activity; however, many TPs are still unknown since several transformation processes are possible (e. g. human and animal metabolism, WWTP activities, environmental factors etc.). In this work, three of the most used SAs, i.e., sulfamethoxazole (SMX), sulfapyridine (SPY), and sulfadiazine (SDZ), were incubated for 20 days in a batch reactor with activated sludge under controlled conditions. Then, the water sample was extracted and analyzed by ultra-high performance liquid chromatography-high resolution mass spectrometry in the data dependent acquisition (DDA) mode. Starting from the literature data, the possible transformation pathways were studied, and for each SA, a list of TPs was hypothesized and used for the identification. The raw data files were processed with Compound Discoverer, and 44 TPs (18, 13, and 13 TPs for SMX, SPY, and SDZ, respectively), including multiple TPs, were manually validated. To overcome the limitation of the DDA, the identified TPs were used in an inclusion list to analyze WWTP samples by a suspect screening approach. In this way, 4 SMX TPs and 5 SPY TPs were tentatively identified together with their parent compounds. Among these TPs, 5 of 9 were acetylated forms, in agreement with previous literature reporting that acetylation is the predominant SA transformation.

New insight into fate and transport of organic compounds from pollution sources to aquatic environment using non-targeted screening: A wastewater treatment plant case study

A variety of chemicals discharged into the aquatic environment by the wastewater treatment plant (WWTP), which is a potential source of hazard to the ecological environment and human health. This study established a novel analytical method for all compounds using non-targeted screening to comprehensively explore the fate and transport of organic compounds from WWTP to aquatic environment. 3967 and 3636 features were detected in WWTP samples and river samples, respectively. Multi-level classification was applied to all identified compounds, and results showed that aliphatics were dominant in both abundance and response, accounting for an average of 35.49 % and 74.10 %, respectively. A total of 88 Emerging Contaminants (ECs), including 22 endocrine disrupting chemicals (EDCs), 12 pharmaceuticals and personal care products (PPCPs), 12 pesticides, 10 volatile organic compounds (VOCs), 5 persistent organic pollutants (POPs) and 27 chemicals with other uses, were identified from all compounds, and their traceability analysis was performed. Furthermore, the contribution rate of organic compounds from WWTP effluent to river was calculated to be 33.60 % by the analysis of source-sink relationship. An in-depth and comprehensive exploration of the fate and transport of all organic compounds will help to provide guidelines for the treatment technologies and achieve the traceability of pollutants.

Environmental and human health impacts of volatile organic compounds: A perspective review

Volatile organic compounds (VOCs) are synthetic chemicals that are broadly used in the production of numerous day-to-day products for residential and commercial-based applications. VOCs are naturally occurring in the environment; however, average annual emissions of man-made volatile organic compounds may have increased dramatically in recent decades. Although many factors were attributed to influencing volatile compounds' emission, only mankind's activities are mainly proclaimed. Since vehicle and industrial pollution are mounting for years and years, urban areas are highly prone to the impacts of VOCs. Generally, volatile compounds are highly spontaneous and readily react with the particles of ambiance and produce a polluted atmosphere through several physical and chemical reactions. Though the volatile compounds play an indispensable role in the manufacture and maintaining the stability of many products, the health impacts associated with their prolonged exposure are gaining attention as recent research reports underline the influence of a wide range of diseases and disorders. Likewise, since the modern way of life applies a lot of day-to-day chemicals, it is imperative to spread a wide knowledge and safety aspects about these chemicals so that people of a wide category can implement preventive measures according to their exposure and living style. In this context, the review article attempts to shed light on past and current updates concerning the relationship between VOCs exposure and environmental and human health impacts.

Analytical key issues and challenges in the LC-MS/MS determination of antibiotics in wastewater

The research on antibiotics occurrence in the aquatic environment has become a hot topic in the last years due to their potential negative effects, associated to possible bacterial antibiotic-resistance, after continuous exposure to these compounds. Most of antibiotic residues are not completely removed in the wastewater treatment plants (WWTPs) and end up in the aquatic environment through treated wastewater (WW). The development of reliable analytical methodologies for the determination of antibiotics in influent (IWW) and effluent wastewater (EWW) is needed with different purposes, among others: monitoring their occurrence in the aquatic environment, performing environmental risk assessment, estimating removal efficiencies of WWTPs, or estimating the consumption of these compounds. In this paper, we perform an in-depth investigation on analytical key issues that pose difficulties in the determination of antibiotics in complex matrices, such as WW, and we identify challenges to be properly addressed for successful analysis. The analytical technique selected was liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), as it is the most powerful and widely applied at present for antibiotic residues determination. The mass spectrometric behavior of 18 selected antibiotics, the chromatographic performance, ion ratio variations associated to the sample matrix when using different precursor ions or protomers, and the macrolides adsorption to glass vial, were some of the issues studied in this work. On the basis of the detailed study performed, an analytical LC-MS/MS method based on sample direct injection has been developed for quantification of 18 antibiotics in IWW and EWW, allowing their determination at low ng L^-1 levels.

Enhancing spectral quality in complex environmental matrices: Supporting suspect and non-target screening in zebra mussels with ion mobility

Identification of bioaccumulating contaminants of emerging concern (CECs) via suspect and non-target screening remains a challenging task. In this study, ion mobility separation with high-resolution mass spectrometry (IM-HRMS) was used to investigate the effects of drift time (DT) alignment on spectrum quality and peak annotation for screening of CECs in complex sample matrices using data independent acquisition (DIA). Data treatment approaches (Binary Sample Comparison) and prioritisation strategies (Halogen Match, co-occurrence of features in biota and the water phase) were explored in a case study on zebra mussel (Dreissena polymorpha) in Lake Mälaren, Sweden's largest drinking water reservoir. DT alignment evidently improved the fragment spectrum quality by increasing the similarity score to reference spectra from on average (±standard deviation) 0.33 ± 0.31 to 0.64 ± 0.30 points, thus positively influencing structure elucidation efforts. Thirty-two features were tentatively identified at confidence level 3 or higher using MetFrag coupled with the new PubChemLite database, which included predicted collision cross-section values from CCSbase. The implementation of predicted mobility data was found to support compound annotation. This study illustrates a quantitative assessment of the benefits of IM-HRMS on spectral quality, which will enhance the performance of future screening studies of CECs in complex environmental matrices.

Prediction of Retention Time and Collision Cross Section (CCSH+, CCSH-, and CCSNa+) of Emerging Contaminants Using Multiple Adaptive Regression Splines

Ultra-high performance liquid chromatography coupled to ion mobility separation and high-resolution mass spectrometry instruments have proven very valuable for screening of emerging contaminants in the aquatic environment. However, when applying suspect or nontarget approaches (i.e., when no reference standards are available), there is no information on retention time (RT) and collision cross-section (CCS) values to facilitate identification. In silico prediction tools of RT and CCS can therefore be of great utility to decrease the number of candidates to investigate. In this work, Multiple Adaptive Regression Splines (MARS) were evaluated for the prediction of both RT and CCS. MARS prediction models were developed and validated using a database of 477 protonated molecules, 169 deprotonated molecules, and 249 sodium adducts. Multivariate and univariate models were evaluated showing a better fit for univariate models to the experimental data. The RT model (R² = 0.855) showed a deviation between predicted and experimental data of ±2.32 min (95% confidence intervals). The deviation observed for CCS data of protonated molecules using the CCS_H model (R² = 0.966) was ±4.05% with 95% confidence intervals. The CCS_H model was also tested for the prediction of deprotonated molecules, resulting in deviations below ±5.86% for the 95% of the cases. Finally, a third model was developed for sodium adducts (CCS_Na, R² = 0.954) with deviation below ±5.25% for 95% of the cases. The developed models have been incorporated in an open-access and user-friendly online platform which represents a great advantage for third-party research laboratories for predicting both RT and CCS data.

Sustainable Treatment Techniques for Emerging Pollutants—The Case of Personal Hygiene Products

Personal care products (PCPs) enter wastewater primarily through greywater. Treatment plants have not been able to remove this type of contaminant, although PCP abatement techniques have been developed in recent years. The objective of the current study has been to encounter the sustainable technique that keeps the optimal balance between the criteria considered in the comparison. Therefore, a bibliographic review was conducted in scientific databases of the last eight years, demonstrating that co-composting, anaerobic–aerobic sequencing bioreactors and contaminant absorption through the use of carbon nanotubes are the ones with the least environmental impact. Subsequently, the Saaty and Modified Saaty methods were applied, with a comparative criteria of construction costs, maintenance costs, efficiency and the stage of development. The results indicated that the co-composting technique is the best sustainable technique of those studied, with a score of 0.86/1, which means that the criteria analyzed maintain very close values between them. The co-composting technique yields a low environmental impact in eliminating personal care products. This research work constitutes a practical and easy-to-use tool for decision makers, since it allows finding an optimal elimination treatment for PCPs.

Benefits of Ion Mobility Separation in GC-APCI-HRMS Screening: From the Construction of a CCS Library to the Application to Real-World Samples

The performance of gas chromatography (GC) combined with the improved identification properties of ion mobility separation coupled to high-resolution mass spectrometry (IMS-HRMS) is presented as a promising approach for the monitoring of (semi)volatile compounds in complex matrices. The soft ionization promoted by an atmospheric pressure chemical ionization (APCI) source designed for GC preserves the molecular and/or quasi-molecular ion information enabling a rapid, sensitive, and efficient wide-scope screening. Additionally, ion mobility separation (IMS) separates species of interest from coeluting matrix interferences and/or resolves isomers based on their charge, shape, and size, making IMS-derived collision cross section (CCS) a robust and matrix-independent parameter comparable between instruments. In this way, GC-APCI-IMS-HRMS becomes a powerful approach for both target and suspect screening due to the improvements in (tentative) identifications. In this work, mobility data for 264 relevant multiclass organic pollutants in environmental and food-safety fields were collected by coupling GC-APCI with IMS-HRMS, generating CCS information for molecular ion and/or protonated molecules and some in-source fragments. The identification power of GC-APCI-IMS-HRMS for the studied compounds was assessed in complex-matrix samples, including fish feed extracts, surface waters, and different fruit and vegetable samples.

Centralized and decentralized wastewater-based epidemiology to infer COVID-19 transmission - A brief review

Wastewater-based epidemiology has shown to be a promising and innovative approach to measure a wide variety of illicit drugs that are consumed in the communities. In the same way as for illicit drugs, wastewater-based epidemiology is a promising approach to understand the prevalence of viruses in a community-level.

The ongoing coronavirus disease 2019 (COVID-19) pandemic created an unprecedented burden on public health and diagnostic laboratories all over the world because of the need for massive laboratory testing. Many studies have shown the applicability of a centralized wastewater-based epidemiology (WBE) approach, where samples are collected at WWTPs. A more recent concept is a decentralized approach for WBE where samples are collected at different points of the sewer system and at polluted water bodies. The second being particularly important in countries where there are insufficient connections from houses to municipal sewage pipelines and thus untreated wastewater is discharged directly in environmental waters.

A decentralized approach can be used to focus the value of diagnostic tests in what we call targeted-WBE, by monitoring wastewater in parts of the population where an outbreak is likely to happen, such as student dorms, retirement homes and hospitals. A combination of centralized and decentralized WBE should be considered for an affordable, sustainable, and successful WBE implementation in high-, middle- and low-income countries.

In-situ biological effects, bioaccumulation, and multi-media distribution of organic contaminants in a shallow lake

Anthropogenic activity-impacted aquatic environment contains a complex mixture of contaminants, and ecological risk assessment solely based on chemical analysis is insufficient and biological assessment is required. However, traditional assessment heavily relies on laboratory bioassays, which may cause uncertainty due to inevitable laboratory-related artifact. A self-designed in-situ bioassay system was successfully applied to simultaneously evaluate water and sediment toxicity by co-exposure of two native species, Chinese rare minnows (Gobiocypris rarus) and Asian clams (Corbicula fluminea) in Tai Lake Basin, China. In-situ exposure caused pronouncedly lethal and sublethal effects (i.e., metabolic and oxidative stress, neurotoxicity, reproductive toxicity) on both fish and clams. Meanwhile, multi-media distribution of organic contaminants in water-sediment-biota system was analyzed. Besides hydrophobicity, metabolism was recognized as an influential factor on phase distribution of contaminants in water-fish and sediment-clam systems. Traditional hazard quotient (HQ) method based on environmental concentrations of 98 contaminants showed bias in risk assessment. Instead, a weight of evidence method by integrating three lines of evidence, including in-situ survival, enhanced integrated biomarker response values and environmental concentrations, successfully differentiate high- and moderate-risk sites in the shallow lakes. The present study incorporated in-situ bioassays into risk assessment using a weight of evidence approach, which reduced uncertainty in decision-making.

Removal efficiency for emerging contaminants in a WWTP from Madrid (Spain) after secondary and tertiary treatment and environmental impact on the Manzanares River

The effluents from wastewater treatment plants (WWTPs) can be an important contamination source for receiving waters. In this work, a comprehensive study on the impact of a WWTP from Madrid on the aquatic environment has been performed, including a wide number of pharmaceuticals and pesticides, among them those included in the European Watch List. 24-h composite samples of influent (IWW) and effluent wastewater after secondary (EWW2) and after secondary + tertiary treatment (EWW3) were monitored along two campaigns. Average weekly concentrations in IWW and EWW2 and EWW3 allowed estimating the removal efficiency of the WWTP for pharmaceutical active substances (PhACs). In addition, the impact of EWW3 on the water quality of the Manzanares River was assessed, in terms of PhAC and pesticide concentrations, through analysis of the river water collected upstream and downstream of the discharge point. After a preliminary risk assessment, a detailed evaluation of the impact on the aquatic environment, including a toxicological study and screening of pharmaceutical metabolites, was made for the seven most relevant PhACs: sulfamethoxazole, azithromycin and clarithromycin (antibiotics), metoprolol (antihypertensive), diclofenac (anti-inflammatory/analgesic), irbesartan (antihypertensive), and the antidepressant venlafaxine. Among selected PhACs, irbesartan, clarithromycin and venlafaxine presented moderate or high risk in the river water downstream of the discharge. Albeit no acute toxicity was detected, more detailed studies should be carried out for these substances, including additional toxicological studies, to set up potential sublethal and chronic effects on aquatic organisms.

Target and Suspect Screening of Pharmaceuticals and their Transformation Products in the Klip River, South Africa, using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry

In spite of recent reports about the presence of pharmaceuticals in African water bodies, their prevalence has still not been sufficiently quantified. The few available studies have mostly focused on a limited number of pharmaceuticals. In the present study, a suspect screening of 92 compounds (mainly pharmaceuticals and their transformation products) along the Klip River, South Africa was conducted, followed by target monitoring of 21 of the detected pharmaceuticals. The experimental approach was based on solid-phase extraction followed by analysis with ultra-high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UHPLC-QTOF-MS). The results revealed 47 pharmaceuticals, 31 of which were detected for the first time in South African waters. Seven detected pharmaceuticals (propyphenazole, sulfamerazine, levamisole, tryptophan, dibucaine, albuterol, and fenpropimorph) are not approved medications in South Africa. Six pharmaceutical metabolites were detected for the first time in South Africa. Pharmaceuticals with the highest concentrations in river water were flumequine (0.257 µg L^-1 ), oxolinic acid (0.355 µg L^-1 ), and acetaminophen (0.432 µg L^-1 ). Oxolinic acid presented the highest hazard quotient, 48.6, indicating a risk of toxicity to aquatic organisms. Hazard quotients for other pharmaceuticals were below 1, except that of flumequine, which reached 1.285. These results suggest a need for further research into the fate of pharmaceuticals in surface waters, and a quantification of the risks associated with the identified drugs because they are likely to accumulate in the tissues of fish/aquatic organisms, thus affecting humans. Environ Toxicol Chem 2022;41:437-447. © 2021 SETAC.

Characterization of the contamination fingerprint of wastewater treatment plant effluents in the Henares River Basin (central Spain) based on target and suspect screening analysis

The interest in contaminants of emerging concern (CECs) has increased lately due to their continued emission and potential ecotoxicological hazards. Wastewater treatment plants (WWTPs) are generally not capable of eliminating them and are considered the main pathway for CECs to the aquatic environment. The number of CECs in WWTPs effluents is often so large that complementary approaches to the conventional target analysis need to be implemented. Within this context, multitarget quantitative analysis (162 compounds) and a suspect screening (>40,000 suspects) approaches were applied to characterize the CEC fingerprint in effluents of five WWTPs in the Henares River basin (central Spain) during two sampling campaigns (summer and autumn). The results indicated that 76% of the compounds quantified corresponded to pharmaceuticals, 21% to pesticides and 3% to industrial chemicals. Apart from the 82 compounds quantified, suspect screening increased the list to 297 annotated compounds. Significant differences in the CEC fingerprint were observed between summer and autumn campaigns and between the WWTPs, being those serving the city of Alcalá de Henares the ones with the largest number of compounds and concentrations. Finally, a risk prioritization approach was applied based on risk quotients (RQs) for algae, invertebrates, and fish. Azithromycin, diuron, chlortoluron, clarithromycin, sertraline and sulfamethoxazole were identified as having the largest risks to algae. As for invertebrates, the compounds having the largest RQs were carbendazim, fenoxycarb and eprosartan, and for fish acetaminophen, DEET, carbendazim, caffeine, fluconazole, and azithromycin. The two WWTPs showing higher calculated Risk Indexes had tertiary treatments, which points towards the need of increasing the removal efficiency in urban WWTPs. Furthermore, considering the complex mixtures emitted into the environment and the low dilution capacity of Mediterranean rivers, we recommend the development of detailed monitoring plans and stricter regulations to control the chemical burden created to freshwater ecosystems.

Combined lethal toxicity, biochemical responses, and gene expression variations induced by tebuconazole, bifenthrin and their mixture in zebrafish (Danio rerio)

Pesticides commonly occur as mixtures in an aqueous environment, causing deleterious effects on human health and the environment. However, the mechanism underlying the combined effects on aqueous organisms remains largely unknown, especially at low concentrations. In the current study, we inspected the interactive toxicity of tebuconazole (TEB), a triazole fungicide, and bifenthrin (BIF), a pyrethroid insecticide, to zebrafish (Danio rerio) using various toxicological assays. Our data revealed that the 96 h-LC50 (lethal concentration 50) values of BIF to fish at different life periods (embryonic, larval, juvenile, and adult periods) ranged from 0.013 (0.011-0.016) to 0.41 (0.35-0.48) mg a.i. L-1, which were lower than that of TEB ranging from 1.1 (0.88-1.3) to 4.8 (4.1-5.7) mg a.i. L-1. Combination of TEB and BIF induced synergetic acute toxicity to embryonic fish. Activities of T-SOD, POD, and GST were distinctly altered in most individual and joint administrations. Expressions of 16 genes associated with oxidative stress, cellular apoptosis, immune system, and endocrine system at the mRNA level were evaluated, and the information revealed that embryonic zebrafish were impacted by both individual compounds and their combinations. Six genes (cas9, P53, gr, TRα, IL-8, and cxcl-clc) exhibited greater changes when exposed to pesticide mixtures. Therefore, the joint effects induced by the pesticides at low concentrations should be considered in the risk assessment of mixtures and regulated as priorities for mixture risk management in the aqueous ecosystem. More research is needed to identify the threshold concentrations of the realistic pesticide mixtures above which synergistic interactions occur.

Estimating the release of chemical substances from consumer products, textiles and pharmaceuticals to wastewater

Chemical emissions from households originate from a wide range of sources and results in highly diverse mixtures. This makes traditional monitoring based on analytical chemistry challenging, especially for compounds that appear in low concentrations. We therefore developed a method for predicting emissions of chemicals from households into wastewater, relying on consumption patterns from multiple data sources. The method was then used to predict the emissions of chemical preparations, chemicals leaching from textiles and prescription pharmaceuticals in Sweden. In total we predicted emissions of 2007 chemicals with a combined emission of 62,659 tonnes per year - or 18 g/person and day. Of the emitted chemicals, 2.0% (w/w) were either classified as hazardous to the environment or were both persistent and mobile. We also show that chemical emissions come from a wide range of uses and that the total emission of any individual chemical is determined primarily by its use pattern, not by the total amount used. This emphasizes the need for continuous updates and additional knowledge generation both on emission factors and excretion rates as well as a need for improved reporting on the intended use of individual chemicals. Finally, we scrutinize the model and its uncertainty and suggest areas that need improvement to increase the accuracy of future emission modelling. We conclude that emission modelling can help guide environmental monitoring and provide input into management strategies aimed at reducing the environmental effect caused by hazardous chemicals.

Wastewater-based epidemiology for illicit drugs: A critical review on global data

Illicit drug use is complex, hidden and often highly stigmatized behaviour, which brings a vast challenge for drug surveillance systems. Drug consumption can be estimated by measuring human excretion products in untreated wastewater, known as wastewater-based epidemiology (WBE). Over the last decade, the application of wastewater-based epidemiology to monitor illicit drug loads increased and WBE is currently applied on a global scale. Studies from over the globe are evaluated with regard to their sampling method, analytical accuracy and consumption calculation, aiming to further reduce relevant uncertainties in order to make reliable comparisons on a global level. Only a limited number is identified as high-quality studies, so further standardization of the WBE approach for illicit drugs is desired especially with regard to the sampling methodology. Only a fraction of the reviewed papers explicitly reports uncertainty ranges for their consumption data. Studies which had the highest reliability are recently published, indicating an improvement in reporting WBE data. Until now, WBE has not been used in large parts of Africa, nor in the Middle East and Russia. An overview of consumption data across the continents on commonly studied drugs (cocaine, MDMA, amphetamine and methamphetamine) is provided. Overall, high consumption rates are confirmed in the US, especially for cocaine and methamphetamine, while relatively low illicit drug consumption is reported in Asia.

Multi-criteria decision-making techniques associated with (Q)SAR risk assessment for ranking surface water microcontaminants identified using LC-QTOF MS

Contaminants of emerging concern (CECs) have been a focus of study for years, with investigations revealing the contamination of different environmental matrices (surface water, soil, air, and sediment) by diverse classes of microcontaminants. Understanding the contamination profiles requires identification and risk assessment of the microcontaminants. In the present work, analysis was made of the presence of 3250 compounds in 27 samples from the Conceição River (Rio Grande do Sul State, Brazil), using an SPE-LC-QTOF MS method. In total, 150 microcontaminants (confirmed and suspected) of different classes, especially pesticides and pharmaceuticals, were identified by an initial qualitative analysis. Subsequently, in silico predictions of eight endpoints, using quantitative structure-activity relationship ((Q)SAR) models, were employed to determine the risk of each previously screened microcontaminant. This large amount of (Q)SAR data, frequently with conflicting information in relation to the responses of the different endpoints, makes it difficult to define which microcontaminants should be prioritized for analysis. Therefore, in order to rank the identified microcontaminants by risk assessment, two multi-criteria decision-making (MCDM) ranking techniques (ToxPi and TOPSIS), associated with a weighting method, were performed to establish the order of priority for further quantitative analysis of the most hazardous microcontaminants. The two rankings were statistically similar, especially for the 20 highest priority microcontaminants. Nonetheless, sensitivity tests carried out for the ToxPi and TOPSIS outputs showed higher performance robustness of TOPSIS, compared to ToxPi. This is the first time that such an approach (screening/(Q)SAR/MCDM methods) has been performed in the context of microcontaminant environmental risk evaluation and demonstrated to be an available strategy to help rank the most concern microcontaminants identified in aqueous environment samples.

Assessment of Environmental Pollution and Human Exposure to Pesticides by Wastewater Analysis in a Seven-Year Study in Athens, Greece

Pesticides have been used in large amounts around the world for decades and are responsible for environmental pollution and various adverse effects on human health. Analysis of untreated wastewater can deliver useful information on pesticides’ use in a particular area and allow the assessment of human exposure to certain substances. A wide-scope screening method, based on liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry, was applied, using both target and suspect screening methodologies. Daily composite influent wastewater samples were collected for seven or eight consecutive days in Athens between 2014 and 2020 and analyzed for 756 pesticides, their environmental transformation products and their human metabolites. Forty pesticides were quantified at mean concentrations up to 4.9 µg/L (tralkoxydim). The most abundant class was fungicides followed by herbicides, insect repellents, insecticides and plant growth regulators. In addition, pesticide transformation products and/or metabolites were detected with high frequency, indicating that research should be focused on them. Human exposure was evaluated using the wastewater-based epidemiology (WBE) approach and 3-ethyl-carbamoyl benzoic acid and cis-1,2,3,6-tetrahydrophthalimide were proposed as potential WBE biomarkers. Wastewater analysis revealed the presence of unapproved pesticides and indicated that there is an urgent need to include more transformation products in target databases.

The relevant role of ion mobility separation in LC-HRMS based screening strategies for contaminants of emerging concern in the aquatic environment

Ion mobility separation (IMS) coupled to high resolution mass spectrometry (IMS-HRMS) is a promising technique for (non-)target/suspect analysis of micropollutants in complex matrices. IMS separates ionized compounds based on their charge, shape and size facilitating the removal of co-eluting isomeric/isobaric species. Additionally, IMS data can be translated into collision cross-section (CCS) values, which can be used to increase the identification reliability. However, IMS-HRMS for the screening of contaminants of emerging concern (CECs) have been scarcely explored. In this study, the role of IMS-HRMS for the identification of CECs in complex matrices is highlighted, with emphasis on when and with which purpose is of use. The utilization of IMS can result in much cleaner mass spectra, which considerably facilitates data interpretation and the obtaining of reliable identifications. Furthermore, the robustness of IMS measurements across matrices permits the use of CCS as an additional relevant parameter during the identification step even when reference standards are not available. Moreover, an effect on the number of true and false identifications could be demonstrated by including IMS restrictions within the identification workflow. Data shown in this work is of special interest for environmental researchers dealing with the detection of CECs with state-of-the-art IMS-HRMS instruments.

Pharmaceuticals and environmental risk assessment in municipal wastewater treatment plants and rivers from Peru

This is the first study dealing with removal of the pharmaceutical substances in municipal wastewater treatment plants (MWWTPs) from Peru and the impact of these compounds in surface waters receiving treated wastewater. To this aim, samples from MWWTP of Lima (Peruvian Coast), MWWTP of Cusco, Puno and Juliaca (Peruvian Highlands), as well surface water (confluence of Torococha and Coata rivers in Juliaca) were analyzed. A total of 38 target pharmaceuticals were included in this study and were determined by Liquid Chromatography coupled to tandem Mass Spectrometry (LC-MS/MS). Around 60% and 75% of the target pharmaceuticals could be quantified in surface water and MWWTPs, respectively. Acetaminophen was the drug found at the highest concentration, and it was present in all the treated wastewater samples reaching average values above 100 μg/L in the department of Puno. The gabapentin anti-epileptic drug (up to 11.85 μg/L in MWWTP Lima) and the antibiotics clarithromycin, trimethoprim, ciprofloxacin, sulfamethoxazole and azithromycin (1.86 to 4.47 μg/L in MWWTP Lima) were also found at moderate concentrations in the treated wastewater. In surface water, the highest concentration corresponded also to acetaminophen (28.70 μg/L) followed by sulfamethoxazole (4.36 μg/L). As regards the pharmaceuticals removal, data of this work showed that the MWWTP Cusco (aerobic biologic process by synthetic trickling filters as secondary treatment) was more efficient than the MWWTP Lima (a preliminary treatment that combines grilles, sand trap, degreaser-aerated and sieved of 1.0 mm). However, many pharmaceuticals (around 50% of the compounds investigated) presented concentrations in treated wastewater similar or even higher than in influent wastewater. The environmental ecological risk of pharmaceuticals was assessed based on calculated Risk Quotient (RQ) in the treated wastewater and surface water from the concentration data found in the samples. According to our data, three antibiotics (clarithromycin, ciprofloxacin, clindamycin) and the analgesic acetaminophen posed high environmental risk (RQ ≥ 1) on the aquatic environment. In the river, all antibiotics (except norfloxacin) as well as the analgesic-anti-inflammatory compounds acetaminophen, diclofenac posed a high environmental risk (RQ ≥ 1). Based on data reported in this work for the first time in water samples from Peru, it can be deduced that the treatment processes applied in important cities from Peru are not enough efficient to remove pharmaceuticals in wastewater. As a consequence, severe environmental risks associated to the presence of pharmaceuticals in treated wastewater and surface water are expected; so complementary treatment processes should be implemented in the MWWTPs for a more efficient elimination of these compounds.

Headspace solid-phase microextraction based on the metal-organic framework CIM-80(Al) coating to determine volatile methylsiloxanes and musk fragrances in water samples using gas chromatography and mass spectrometry

A headspace solid-phase microextraction (HS-SPME) method was developed using the metal-organic framework (MOF) CIM-80(Al) as extraction phase and in combination with gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of 6 methylsiloxanes and 7 musk fragrances in different environmental waters. The chromatographic separation was optimized in different GC instruments equipped with different detectors, allowing the correct separation and identification of the compounds. The HS-SPME method was optimized using a Box-Behnken experimental design, while the validation was carried out together with the most suitable commercial fiber (divinylbenzene/polydimethylsiloxane) for comparison purposes. The MOF-based coating was particularly efficient for the determination of volatile methylsiloxanes, showing moderately lower limits of detection (of 0.2 and 0.5 μg L^-1versus 0.6 μg L^-1 for cyclic methylsiloxanes) and slightly better precision (relative standard deviation values lower than 17% versus 22%) than the commercial coating, while avoiding the cross-contamination issues associated to the polymeric composition of commercial fibers. The method was applied for the analysis of seawater and wastewater samples, allowing the quantification of several analytes and the assessment of matrix effects. The proposed HS-SPME method using the CIM-80(Al) fiber constitutes a more environmentally friendly, simpler, and efficient strategy in comparison with other sample preparation methods using different extraction techniques, while the use of a MOF as fiber sorbent constitutes a potential alternative to exploit the features of SPME for the challenging environmental monitoring of these compounds.

Suspect screening workflow comparison for the analysis of organic xenobiotics in environmental water samples

Suspect screening techniques are able to determine a broader range of compounds than traditional target analysis. However, the performance of the suspect techniques relies on the procedures implemented for peak annotation and for this, the list of potential candidates is clearly a limiting factor. In order to study this effect on the number of compounds annotated in environmental water samples, a method was validated in terms of absolute recoveries, limits of quantification and identification, as well as the peak picking capability of the software (Compound Discoverer 2.1) using a target list of 178 xenobiotics. Four suspect screening workflows using different suspect lists were compared: (i) the Stoffident list, (ii) all the NORMAN lists, (iii) suspects containing C, H, O, N, S, P, F or Cl in their molecular formula with more than 10 references in Chemspider and (iv) the mzCloud library. The results were compared in terms of the number of annotated compounds at each confidence level. The same 8 compounds (atenolol, caffeine, caprolactam, carbendazim, cotinine, diclofenac, propyphenazone and trimetoprim) were annotated at the highest confidence level using the four workflows. Remarkable differences were observed for lower confidence levels but only 4 features were annotated at different levels by the four workflows. While the third approach provided the highest number of annotated features, the workflow based on the mzCloud library rendered satisfactory results with a simpler approach. Finally, this latter approach was extended to the analysis of organic xenobiotics in different environmental water samples.

A Review of Nanocomposite-Modified Electrochemical Sensors for Water Quality Monitoring

Electrochemical sensors play a significant role in detecting chemical ions, molecules, and pathogens in water and other applications. These sensors are sensitive, portable, fast, inexpensive, and suitable for online and in-situ measurements compared to other methods. They can provide the detection for any compound that can undergo certain transformations within a potential window. It enables applications in multiple ion detection, mainly since these sensors are primarily non-specific. In this paper, we provide a survey of electrochemical sensors for the detection of water contaminants, i.e., pesticides, nitrate, nitrite, phosphorus, water hardeners, disinfectant, and other emergent contaminants (phenol, estrogen, gallic acid etc.). We focus on the influence of surface modification of the working electrodes by carbon nanomaterials, metallic nanostructures, imprinted polymers and evaluate the corresponding sensing performance. Especially for pesticides, which are challenging and need special care, we highlight biosensors, such as enzymatic sensors, immunobiosensor, aptasensors, and biomimetic sensors. We discuss the sensors' overall performance, especially concerning real-sample performance and the capability for actual field application.

Non-targeted tandem mass spectrometry enables the visualization of organic matter chemotype shifts in coastal seawater

Urbanization along coastlines alters marine ecosystems including contributing molecules of anthropogenic origin to the coastal dissolved organic matter (DOM) pool. A broad assessment of the nature and extent of anthropogenic impacts on coastal ecosystems is urgently needed to inform regulatory guidelines and ecosystem management. Recently, non-targeted tandem mass spectrometry approaches are gaining momentum for the analysis of global organic matter composition (chemotypes) including a wide array of natural and anthropogenic compounds. In line with these efforts, we developed a non-targeted liquid chromatography tandem mass spectrometry (LC-MS/MS) workflow that utilizes advanced data analysis approaches such as feature-based molecular networking and repository-scale spectrum searches. This workflow allows the scalable comparison and mapping of seawater chemotypes from large-scale spatial surveys as well as molecular family level annotation of unknown compounds. As a case study, we visualized organic matter chemotype shifts in coastal environments in northern San Diego, USA, after notable rain fall in winter 2017/2018 and highlight potential anthropogenic impacts. The observed seawater chemotype, consisting of 4384 LC-MS/MS features, shifted significantly after a major rain event. Molecular drivers of this shift could be attributed to multiple anthropogenic compounds, including pesticides (Imazapyr and Isoxaben), cleaning products (Benzyl-tetradecyl-dimethylammonium) and chemical additives (Hexa (methoxymethyl)melamine) and potential degradation products. By expanding the search of identified xenobiotics to other public tandem mass spectrometry datasets, we further contextualized their possible origin and show their importance in other ecosystems. The mass spectrometry and data analysis pipelines applied here offer a scalable framework for future molecular mapping and monitoring of marine ecosystems, which will contribute to a deliberate assessment of how chemical pollution impacts our oceans.

Suspect and non-target screening: the last frontier in environmental analysis

Suspect and non-target screening (SNTS) techniques are arising as new analytical strategies useful to disentangle the environmental occurrence of the thousands of exogenous chemicals present in our ecosystems. The unbiased discovery of the wide number of substances present over environmental analysis needs to find a consensus with powerful technical and computational requirements, as well as with the time-consuming unequivocal identification of discovered analytes. Within these boundaries, the potential applications of SNTS include the studies of environmental pollution in aquatic, atmospheric, solid and biological samples, the assessment of new compounds, transformation products and metabolites, contaminant prioritization, bioremediation or soil/water treatment evaluation, and retrospective data analysis, among many others. In this review, we evaluate the state of the art of SNTS techniques going over the normalized workflow from sampling and sample treatment to instrumental analysis, data processing and a brief review of the more recent applications of SNTS in environmental occurrence and exposure to xenobiotics. The main issues related to harmonization and knowledge gaps are critically evaluated and the challenges of their implementation are assessed in order to ensure a proper use of these promising techniques in the near future.

Current trends and advances in analytical techniques for the characterization and quantification of biologically recalcitrant organic species in sludge and wastewater: A review

The study of organic matter in wastewater is a major regulatory and environmental issue and requires new developments to identify non-biodegradable refractory compounds, produced mainly by thermal treatments. Recent advances linking physicochemical properties to spectroscopic analyzes (UV, Fluorescence, IR) have shown that the refractory property is favored by several physicochemical parameters: weight, hydrophobicity, aromaticity and chemical functions. Currently, the most effective developments for the quantification of refractory compounds are obtained with hyphenated methods, based on steric separation of the macromolecular species by steric exclusion chromatography (SEC)/PDA/Fluorescence systems. Hyphenated techniques using High Resolution Mass Spectrometry (HRMS), ultra-high-resolution mass spectrometry with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and NMR have been developed to analyze macromolecules in wastewater with minor sample preparation procedures. A particular class has been identified, the melanoidins, generated by Maillard reactions between sugars, amino acids, peptides and proteins present in wastewater and sludge, but low molecular weight compounds formed as intermediates, such as ketones, aldehydes, pyrazines, pyridines or furans, are also recalcitrant and are complex to identify in the complex matrices. The lack of available standards for the study of these compounds requires the use of specific techniques and data processing. Advances in chemometrics are obtained in the development of molecular or physicochemical indices resulting from the data generated by the analytical detectors, such as aromaticity calculated by SUVA₂₅₄ and determined by UV, fluorescence, molar mass, H/C ratio or structural studies (measuring the amount of unsaturated carbon) given by hyphenated techniques with SEC. It is clear that nitrogen compounds are widely involved in refractoriness. New trends in nitrogen containing compounds characterization follow two axes: through SEC/PDA/Fluorescence and HRMS/NMR techniques with or without separation. Other techniques widely used in food or marine science are also being imported to this study, as it can be seen in the use of "omics" methods, high-performance thin layer chromatography (HPTLC) and chromatography at the critical condition, rounding out the important developments around SEC. While improving the performance of stationary phases is one of the challenges, it results in a fundamental understanding of the retention mechanisms that today provide us with more information on the structures identified. The main objective of this review is to present the spectroscopic and physicochemical techniques used to qualify and characterize refractoriness with a specific focus on chemometric approaches.

Reactivity-directed analysis - a novel approach for the identification of toxic organic electrophiles in drinking water

Drinking water consumption results in exposure to complex mixtures of organic chemicals, including natural and anthropogenic chemicals and compounds formed during drinking water treatment such as disinfection by-products. The complexity of drinking water contaminant mixtures has hindered efforts to assess associated health impacts. Existing approaches focus primarily on individual chemicals and/or the evaluation of mixtures, without providing information about the chemicals causing the toxic effect. Thus, there is a need for the development of novel strategies to evaluate chemical mixtures and provide insights into the species responsible for the observed toxic effects. This critical review introduces the application of a novel approach called Reactivity-Directed Analysis (RDA) to assess and identify organic electrophiles, the largest group of known environmental toxicants. In contrast to existing in vivo and in vitro approaches, RDA utilizes in chemico methodologies that investigate the reaction of organic electrophiles with nucleophilic biomolecules, including proteins and DNA. This review summarizes the existing knowledge about the presence of electrophiles in drinking water, with a particular focus on their formation in oxidative treatment systems with ozone, advanced oxidation processes, and UV light, as well as disinfectants such as chlorine, chloramines and chlorine dioxide. This summary is followed by an overview of existing RDA approaches and their application for the assessment of aqueous environmental matrices, with an emphasis on drinking water. RDA can be applied beyond drinking water, however, to evaluate source waters and wastewater for human and environmental health risks. Finally, future research demands for the detection and identification of electrophiles in drinking water via RDA are outlined.

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.

Improving Target and Suspect Screening High-Resolution Mass Spectrometry Workflows in Environmental Analysis by Ion Mobility Separation

Currently, the most powerful approach to monitor organic micropollutants (OMPs) in environmental samples is the combination of target, suspect, and nontarget screening strategies using high-resolution mass spectrometry (HRMS). However, the high complexity of sample matrices and the huge number of OMPs potentially present in samples at low concentrations pose an analytical challenge. Ion mobility separation (IMS) combined with HRMS instruments (IMS-HRMS) introduces an additional analytical dimension, providing extra information, which facilitates the identification of OMPs. The collision cross-section (CCS) value provided by IMS is unaffected by the matrix or chromatographic separation. Consequently, the creation of CCS databases and the inclusion of ion mobility within identification criteria are of high interest for an enhanced and robust screening strategy. In this work, a CCS library for IMS-HRMS, which is online and freely available, was developed for 556 OMPs in both positive and negative ionization modes using electrospray ionization. The inclusion of ion mobility data in widely adopted confidence levels for identification in environmental reporting is discussed. Illustrative examples of OMPs found in environmental samples are presented to highlight the potential of IMS-HRMS and to demonstrate the additional value of CCS data in various screening strategies.

Occurrence and ecological risks of pharmaceuticals in a Mediterranean river in Eastern Spain

Pharmaceuticals are biologically active molecules that may exert toxic effects to a wide range of aquatic organisms. They are considered contaminants of emerging concern due to their common presence in wastewaters and in the receiving surface waters, and the lack of specific regulations to monitor their environmental occurrence and risks. In this work, the environmental exposure and risks of pharmaceuticals have been studied in the Mijares River, Eastern Mediterranean coast (Spain). A total of 57 surface water samples from 19 sampling points were collected in three monitoring campaigns between June 2018 and February 2019. A list of 40 compounds was investigated using a quantitative target UHPLC-MS/MS method. In order to complement the data obtained, a wide-scope screening of pharmaceuticals and metabolites was also performed by UHPLC-HRMS. The ecological risks posed by the pharmaceutical mixtures were evaluated using species sensitivity distributions built with chronic toxicity data for aquatic organisms. In this study, up to 69 pharmaceuticals and 9 metabolites were identified, out of which 35 compounds were assessed using the quantitative method. The highest concentrations in water corresponded to acetaminophen, gabapentin, venlafaxine, valsartan, ciprofloxacin and diclofenac. The compounds that were found to exert the highest toxic pressure on the aquatic ecosystems were principally analgesic/anti-inflammatory drugs and antibiotics. These were: phenazone > azithromycin > diclofenac, and to a lower extent norfloxacin > ciprofloxacin > clarithromycin. The monitored pharmaceutical mixtures are expected to exert severe ecological risks in areas downstream of WWTP discharges, with the percentage of aquatic species affected ranging between 65% and 82% in 3 out of the 19 evaluated sites. In addition, five antibiotics were found to exceed antibiotic resistance thresholds, thus potentially contributing to resistance gene enrichment in environmental bacteria. This work illustrates the wide use and impact of pharmaceuticals in the area under study, and the vulnerability of surface waters if only conventional wastewater treatments are applied. Several compounds included in this study should be incorporated in future water monitoring programs to help in the development of future regulations, due to their potential risk to the aquatic environment.

Economically feasible strategy for confirmation of pharmaceuticals in hospital effluent using screening analysis

The contamination of aquatic systems by pharmaceuticals has received considerable attention in recent decades, because these substances are increasingly detected in the environment. This is due to the abundant use of pharmaceuticals by the population and, consequently, their constant introduction into aquatic systems through domestic, industrial, and hospital wastewaters. Hospital effluents have highly complex compositions and present potential toxicity towards the environment. In this work, a screening methodology was developed to evaluate the occurrence of pharmaceutical products in hospital wastewater, using a viable, easy, and economical strategy employing commercial pharmaceutical compounds for screening analysis. Six samplings of hospital wastewater were carried out monthly (from winter until summer). The samples were filtered and pre-concentrated/extracted using solid phase extraction (SPE). The pharmaceuticals screening procedure required the construction of two databases, one for each ionization mode (positive and negative), which contained information that allowed the identification of the presence of these pharmaceuticals in the studied samples. Commercial pharmaceutical compounds were used as analytical standards. Based on this strategy and, using liquid chromatography coupled to high resolution mass spectrometry, it was possible to screen 110 pharmaceuticals and, from these, to confirm the presence of 38 pharmaceuticals in analyzed samples. These results indicate the analytes that should be taken into account in the further development of quantitative methods for pharmaceutical analysis.

Recent progresses in analytical GC and LC mass spectrometric based-methods for the detection of emerging chlorinated and brominated contaminants and their transformation products in aquatic environment

This paper is an overview of screening methods recently developed for emerging halogenated contaminants and their transformation products. The target screening methods are available only for a limited number of emerging pollutants since the reference standards for these compounds are not always available, but a risk assessment of those micropollutants in environment must be performed anyhow. Therefore, the chromatographic techniques hyphenated with high resolution mass spectrometry (HRMS) trend to become indispensable methods for suspect and non-target screening of emerging halogenated contaminants. HRMS is also an effective tool for tentatively identification of the micropollutants' transformation products existing in much lower concentrations. To assess the transformation pathway of halogenated contaminants in environment, the non-target screening methods must be combined with biodegradation lab experiments and also with advanced oxidation and reduction processes that can mimic the transformation on these contaminants in environment. It is expected that in the future, the accurate-mass full-spectra of transformation products recorded by HRMS will be the basic information needed to elucidate the transformation pathways of emerging halogenated contaminants in aquatic environment.

Identification of Aquifer Recharge Sources as the Origin of Emerging Contaminants in Intensive Agricultural Areas. La Plana de Castellón, Spain

In urban, industrial, and agricultural areas, a vast array of contaminants may be found because they are introduced into the aquifers by different recharge sources. The emerging contaminants (ECs) correspond to unregulated contaminants, which may be candidates for future regulation depending on the results of research into their potential effects on health and on monitoring data regarding their occurrence. ECs frequently found in wastewater, such as acetaminophen, carbamazepine, primidone, and sulfamethoxazole, may be good indicators of the introduction of the reclaimed water to the aquifers. The resistance of the ECs to removal in wastewater treatment plants (WWTPs) causes them to be appropriate sewage markers. Plana de Castellón (Spain) is a coastal area that has been characterized by intensive citrus agriculture since the 1970s. Traditionally, in the southern sector of Plana de Castellón, 100% of irrigation water comes from groundwater. In recent years, local farmers have been using a mixture of groundwater and reclaimed water from wastewater treatment plants (WWTPs) to irrigate the citrus. The aims of the present study were: (i) to assess the occurrences, spatial distributions, and concentrations of selected ECs, including 32 antibiotics, 8 UV filters, and 2 nonsteroidal anti-inflammatory drugs, in groundwater in a common agricultural context; (ii) to identify the recharge (pollution) sources acting as the origin of the ECs, and (iii) to suggest ECs as indicators of reclaimed water arrival in detrital heterogeneous aquifers. The obtained data provided relevant information for the management of water resources and elucidated the fate and behavior of emerging contaminants in similar contexts.

Suspect and Nontarget Screening for Contaminants of Emerging Concern in an Urban Estuary

This study used suspect and nontarget screening with high-resolution mass spectrometry to characterize the occurrence of contaminants of emerging concern (CECs) in the nearshore marine environment of Puget Sound (WA). In total, 87 non-polymeric CECs were identified; those confirmed with reference standards (45) included pharmaceuticals, herbicides, vehicle-related compounds, plasticizers, and flame retardants. Eight polyfluoroalkyl substances were detected; perfluorooctanesulfonic acid (PFOS) concentrations were as high as 72-140 ng/L at one location. Low levels of methamphetamine were detected in 41% of the samples. Transformation products of pesticides were tentatively identified, including two novel transformation products of tebuthiuron. While a hydrodynamic simulation, analytical results, and dilution calculations demonstrated the prevalence of wastewater effluent to nearshore marine environments, the identity and abundance of selected CECs revealed the additional contributions from stormwater and localized urban and industrial sources. For the confirmed CECs, risk quotients were calculated based on concentrations and predicted toxicities, and eight CECs had risk quotients >1. Dilution in the marine estuarine environment lowered the risks of most wastewater-derived CECs, but dilution alone is insufficient to mitigate risks of localized inputs. These findings highlighted the necessity of suspect and nontarget screening and revealed the importance of localized contamination sources in urban marine environments.

Investigation of pharmaceuticals and their metabolites in Brazilian hospital wastewater by LC-QTOF MS screening combined with a preliminary exposure and in silico risk assessment

This work evaluates the occurrence of pharmaceuticals, with special emphasis on their metabolites, in raw hospital wastewater (HWW) using wide-scope screening based on liquid chromatography coupled to high resolution mass spectrometry. The applied strategy uses an extended purpose-built database, containing >1000 pharmaceuticals and 250 metabolites. Raw HWW samples from a hospital located in south Brazil were collected over six months, with a monthly sampling frequency. Accurate-mass full-spectrum data provided by quadrupole-time of flight MS allowed the identification of 43 pharmaceuticals and up to 31 metabolites in the samples under study. Additionally, other four metabolites not included in the initial database could be identified using a complementary strategy based on the common fragmentation pathway between the parent compound and its metabolites. Nine metabolites derived from four pharmaceuticals were identified in the raw HWW samples, whereas their parent compounds were not found in these samples. The results of this work illustrate the importance of including not only parent pharmaceuticals but also their main metabolites in screening analysis. Besides, the inclusion of in silico QSAR predictions allowed assessing the environmental fate and effect of pharmaceuticals and metabolites in terms of biodegradability, as possible Persistent, Bioaccumulative and Toxic (PBT) compounds, and their potential hazard to the aquatic environment.