Targeted and non-targeted liquid chromatography-mass spectrometric workflows for identification of transformation products of emerging pollutants in the aquatic environment

Assessing Event-Driven Dynamics of Pesticides and Transformation Products in an Agricultural Stream Using Comprehensive Target, Suspect, and Nontarget Analysis

A comprehensive assessment of pesticide transport in surface waters is challenging due to discharge characteristics and the occurrence of transformation products (TPs). Detailed long-term sampling of pesticide concentrations, including rainfall and pesticide application events, is still lacking to better predict pesticide transport pathways and toxicity within agricultural catchments. In the present study, pesticide and TP transport dynamics were evaluated over a three-year monitoring period, which included 12 stormwater events and 7 dry events. An extensive target screening for 328 pesticides was conducted, while simultaneously performing suspect and nontarget analysis (SNTA) using liquid chromatography high-resolution mass spectrometry. Twenty-one pesticides and two TPs associated with the main crop, rice, were identified as the major pollutants. The risk assessment results, based on the stepwise toxicity data collection, suggested that insecticides, primarily neonicotinoids, exhibited severe ecological risk. Additionally, SNTA revealed the presence of 8 parent compounds and 46 TPs. TPs occurred following parent peak periods, indicating that integrated pesticide monitoring is a practical approach to risk assessment. A precautionary approach using SNTA of parent pesticides and TP identification suggests that the potential aquatic effects of pesticide TPs may be underestimated by a conventional pesticide monitoring strategy.

Incorporating Transformation Products for an Integrated Assessment of Antibiotic Pollution and Risks in Surface Water

The widespread presence of antibiotics in aquatic ecosystems is a global challenge, yet the occurrence and risks associated with their transformation products (TPs) remain poorly understood. This study investigated the occurrence and potential risks of antibiotics and their TPs in water along the Chaobai River in Beijing. We used high-resolution mass spectrometry and an integrated target, suspect, and nontarget screening approach to identify 21 parent antibiotics and 78 TPs among 90 water samples, with the majority from macrolides and sulfonamides. Notably, target quantification and machine-learning-assisted semiquantification revealed that the cumulative concentrations of TPs were higher than the cumulative concentrations of parent compounds, with average contributions of TPs ranging between 50.7 and 63.7%. Most downstream water samples were largely influenced by domestic sewage, as indicated by the significantly higher concentrations and proportions of TPs, as well as the greater diversity in their composition profiles compared to upstream and reservoir samples. Moreover, of the 78 TPs, 26.9, 67.9, and 6.4% exhibited greater persistence, mobility, or toxicity than their parent antibiotics, respectively. Sixteen macrolide TPs presented both greater ecological risks to aquatic organisms and higher resistance selection risks than their parent antibiotics. TPs contributed substantially to the overall antibiotic-related risks by an average of between 31.2 and 54.1%. This study highlights the occurrence of antibiotic TPs in river water, underscoring the need to consider TPs in comprehensive risk assessments of antibiotics.

Degradation pathways of sulfamethoxazole under phototransformation processes: A data base of the major transformation products for their environmental monitoring

Sulfamethoxazole (SMX) is frequently detected in wastewater and aquatic environments worldwide at concentrations from ng L-1 to μg L-1. Unfortunately, SMX is not completely removed in municipal wastewater treatment plants (WWTPs), thus, SMX and their transformation products (TPs) are discharged into aquatic environments, where can be transformed by phototransformation reactions. In this study, the phototransformation of SMX as well as generation of their major TPs under photolysis and photocatalysis processes was reviewed. SMX can be totally removed under photolysis and photocatalysis processes in aqueous solutions using simulated or natural radiation. Degradation pathways such as isomerization, hydroxylation, fragmentation, nitration, and substitution reactions were identified during the generation of the major TPs of SMX. Particularly, 26 TPs were considered for the creation of a data base of the major TPs of SMX generated under phototransformation processes. These 26 compounds could be used as reference during the SMX monitoring both wastewater and water bodies, using analytic methodologies such as target analysis and suspect screening. A data base of the major TPs of pharmaceuticals active compounds (PhACs) as SMX could help to implementation of best environmental monitoring programs for the study of the environmental risks both PhACs and their TPs with highest occurrence in aquatic environments.

Chemical profiling of organic contaminants in rural surface waters combining target and non-target LC-HRMS/MS analysis

The pollution of natural waters by contaminants of emerging concern (CECs) is one of the pressing problems due to their global distribution and potential negative effects on the environment and human health. In rural areas with lower population density and limited industrial development, less contamination is expected. However, the lack of wastewater treatment plants (WWTPs) or their poor removal efficiency can lead to significant input of pollutants. In this context, 11 streams of rural areas in the Guadalquivir River basin, southeast of Spain, were studied over two years to obtain an overview of the origin and distribution of contaminants. A target method using solid-phase extraction and liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) was developed for the analysis of 316 compounds in surface waters. A total of 78 target analytes were detected, comprising pesticides, pharmaceuticals, personal care products (PCPs), transformation products (TPs), and industrial chemicals. The flame retardant tributyl phosphate (16-3572 ng L-1) was detected in all samples, followed by caffeine (30-8090 ng L-1) and the analgesic tramadol (3-1493 ng L-1). The target approach was combined with a non-target analysis (NTA) strategy to obtain an overall perspective of the chemical profile of unexpected or unknown compounds in the samples. Up to 79 contaminants were tentatively identified, and 12 of them were finally confirmed with standards. Most of the contaminants determined by NTA were pharmaceuticals and their TPs. The results indicated that most of CECs have an urban origin despite traditional agriculture is the main economic activity in this region. Moreover, the absence of WWTPs in small towns is significant, as contamination levels at these sites were comparable to or higher than those in larger populations with sewage treatments.

An integrated approach to evaluating water contaminants and evaporation in agricultural water distribution systems

This study presents an innovative approach for assessing water quality in agricultural irrigation networks, integrating stable isotope analysis, in vivo zebrafish screening, and comprehensive chemical profiling to investigate the occurrence, transformation, and potential toxicity of organic contaminants. Stable isotope analysis was used to measure evaporation as a proxy for water residence time in the canal, while liquid chromatography-high resolution mass spectrometry (LC-HRMS) identified a range of organic compounds in water samples collected from both the irrigation canal and its source river. Results indicated a reduction in contaminant levels in the canal compared to the river, with the most significant evaporation and concentration changes occurring at a holding reservoir, suggesting that managing residence time could help reduce water loss in arid irrigation networks. The data also highlighted how evaporation, particularly during the dry, hot season, influences contaminant dynamics. Hierarchical clustering of LC-HRMS results showed notable differences between the chemical profiles of canal and river samples, indicating that irrigation systems may contribute to the degradation or removal of certain compounds. Over 60 % of detected compounds were naturally derived, with anthropogenic contaminants like pesticides and personal care products further highlighting human impacts. Priority contaminants, including DEET and 2-naphthalene sulfonic acid, likely originated from urban activities upstream. Initial screening using zebrafish embryos showed bioactivity across sites, confirming the presence of contaminants needing further examination. Correlation analysis linked natural compounds to evaporation rates, suggesting that flora and fauna play significant roles in the chemical makeup of canal water. Overall, this approach provides a comprehensive framework for monitoring irrigation water, offering insights into contaminant behavior and supporting the development of standardized methods for assessing chemical fate and ecological risks in agricultural irrigation systems.

Characterization of AhR-mediated potency in sediments from Kongsfjorden, Svalbard: Application of effect-directed analysis and nontarget screening

In this study, we aimed to identify the major aryl hydrocarbon receptor (AhR) agonists in surface sediments (S1-S10, n = 10) from Kongsfjorden, Arctic Svalbard, using effect-directed analysis. High AhR-mediated potencies were observed in the mid-polar fractions and RP-HPLC subfractions (F2.6-F2.8; log KOW 5-8) in the sediments of sites S2 and S3, which are located near abandoned coal mine areas, as assessed by the H4IIE-luc bioassay. The concentrations of traditional polycyclic aromatic hydrocarbon (t-PAHs), emerging PAHs, alkyl-PAHs, and styrene oligomers ranged from 6.1 to 2100 ng g-1 dry weight (dw), 0.5-1000 ng g-1 dw, 47 to 79,000 ng g-1 dw, and 4.2-130 ng g-1 dw, respectively, with elevated levels in S2 and S3. Principal component analysis coupled with multiple linear regression suggested that t-PAHs in sediments primarily originated from coal, petroleum combustion, and coal combustion. Twenty-four target AhR agonists accounted for 3.2%-100% (mean = 47%) of the total AhR-mediated potencies in S2 and S3. Nontarget screening via GC-QTOFMS in the highly potent fractions identified 48 AhR agonist candidates through four-step selection criteria. Among these, 27 compounds were identified as coal-derived substances. VirtualToxLab in silico modeling predicted that most of the 48 tentative AhR agonist candidates could bind to AhR. Overall, our findings indicate significant contamination of the Kongsfjorden sediments by coal-derived substances, highlighting the need for further studies to assess the ecological risks associated with these contaminants.

Quantification Approaches in Non-Target LC/ESI/HRMS Analysis: An Interlaboratory Comparison

Nontargeted screening (NTS) utilizing liquid chromatography electrospray ionization high-resolution mass spectrometry (LC/ESI/HRMS) is increasingly used to identify environmental contaminants. Major differences in the ionization efficiency of compounds in ESI/HRMS result in widely varying responses and complicate quantitative analysis. Despite an increasing number of methods for quantification without authentic standards in NTS, the approaches are evaluated on limited and diverse data sets with varying chemical coverage collected on different instruments, complicating an unbiased comparison. In this interlaboratory comparison, organized by the NORMAN Network, we evaluated the accuracy and performance variability of five quantification approaches across 41 NTS methods from 37 laboratories. Three approaches are based on surrogate standard quantification (parent-transformation product, structurally similar or close eluting) and two on predicted ionization efficiencies (RandFor-IE and MLR-IE). Shortly, HPLC grade water, tap water, and surface water spiked with 45 compounds at 2 concentration levels were analyzed together with 41 calibrants at 6 known concentrations by the laboratories using in-house NTS workflows. The accuracy of the approaches was evaluated by comparing the estimated and spiked concentrations across quantification approaches, instrumentation, and laboratories. The RandFor-IE approach performed best with a reported mean prediction error of 15× and over 83% of compounds quantified within 10× error. Despite different instrumentation and workflows, the performance was stable across laboratories and did not depend on the complexity of water matrices.

Biotransformation pathways of pharmaceuticals and personal care products (PPCPs) during acidogenesis and methanogenesis of anaerobic digestion

Pharmaceuticals and personal care products (PPCPs) exhibit varying biodegradability during the acidogenic and methanogenic phases of anaerobic digestion. However, there is limited information regarding the end products generated during these processes. This work investigates the biotransformation products (BTPs) generated in a two-phase (TP) acidogenic-methanogenic (Ac-Mt) bioreactor using advanced suspect and nontarget strategies. Fourteen BTPs were confidently identified from ten parent PPCPs including carbamazepine (CBZ), naproxen (NPX), diclofenac (DCF), ibuprofen (IBU), acetaminophen (ACT), metoprolol (MTP), sulfamethoxazole (SMX), ciprofloxacin (CIP), methylparaben (MPB) and propylparaben (PPB). These BTPs were linked with oxidation reactions such as hydroxylation, demethylation and epoxidation. Their generation was related to organic acid production, since all metabolites were detected during acidogenesis, with some being subsequently consumed during methanogenesis, e.g., aminothiophenol and kynurenic acid. Another group of BTPs showed increased concentrations under methanogenic conditions, e.g., hydroxy-diclofenac and epoxy-carbamazepine. The most PPCPs showed high removal efficiencies (> 90 %) - SMX, CIP, NPX, MTP, ACT, MPB, PPB, while DCF, CBZ and IBU demonstrated higher persistence - DCF (42 %); CBZ (40 %), IBU (47 %). The phase separation of anaerobic digestion provided a deeper understanding of the biotransformation pathways of PPCPs, in addition to enhancing the biodegradability of the most persistent compounds, i.e., DCF, CBZ and IBU.

Identification of organic contaminants in water and related matrices using untargeted liquid chromatography high-resolution mass spectrometry screening with MS/MS libraries

Nontargeted and suspect screening with liquid chromatography-high resolution mass spectrometry (LC-HRMS) has become an indispensable tool for quality assessment in the aquatic environment - complementary to targeted analysis of organic (micro)contaminants. An LC-HRMS method is presented, suitable for the analysis of a wide variety of water related matrices: surface water, groundwater, wastewater, sediment and sludge, including extracts from passive samplers and on-site solid phase enrichment, while focusing on the data processing aspect of the method. A field study is included to demonstrate the practical application and versatility of the whole process. HRMS/MS data were recorded following LC separation in both (ESI) positive and negative ionization modes using data dependent as well as data independent acquisition. Two vendor (Agilent's Personal Compound Database and Library and from National Institute of Standards and Technology) and one open (MassBank/EU) tandem mass spectral libraries were utilized for the identification of compounds via mass spectral match. The development of a novel software tool for parsing, grouping and reduction of MS/MS features in data files converted to mascot generic format (MGF) helped to substantially decrease the amount of time and effort needed for MS library search. While applying the method, in the course of the entire field study, 18771 detections (from 870 individual compounds) in total were recorded in 275 samples, resulting in 68.3 identified compounds per sample, on average. Among the top ten most frequently detected contaminants across all samples and sample types were pharmaceutical compounds carbamazepine, 4-acetamidoantipyrine, 4-formylaminoantipyrine, tramadol, lamotrigine and phenazone and industrial contaminants toluene-2-sulfonamide, tolytriazole, tris(2-butoxyethyl) phosphate and benzotriazole. Exploratory data analysis methods and tools enabled us to discover organic pollutant occurrence patterns within the comprehensive sets of qualitative data collected from various projects between the years 2018-2023. The results may be used as valuable inputs for future water quality monitoring programs.

Fragmentation characteristics-based nontargeted screening method of exogenous chemical residues in animal-derived foods using reversed-phase and hydrophilic interaction liquid chromatography-high-resolution mass spectrometry

Fragmentation characteristics are crucial for nontargeted screening to discover and identify unknown exogenous chemical residues in animal-derived foods. In this study, first, fragmentation characteristics of 51 classes of exogenous chemical residues were summarized based on experimental mass spectra of standards in reversed-phase and hydrophilic interaction liquid chromatography-high-resolution mass spectrometry (MS) and mass spectra from the MassBank of North America (MoNA) library. According to the proportion of fragmentation characteristics to the total number of chemical residues in each class, four screening levels were defined to classify 51 classes of chemical residues. Then, a nontargeted screening method was developed based on the fragmentation characteristics. The evaluation results of 82 standards indicated that more than 90 % of the chemical residues with MS/MS spectra can be identified at concentrations of 100 and 500 μg/kg, and about 80 % can be identified at 10 μg/kg. Finally, the nontargeted screening method was applied to 16 meat samples and 21 egg samples as examples. As a result, eight chemical residues and transformation products (TPs) of 5 classes in the exemplary samples were found and identified, in which 3 TPs of azithromycin were identified by fragmentation characteristics-assisted structure interpretation. The results demonstrated the practicability of the nontargeted screening method for routine risk screening of food safety.

Exploring the Chemical Space of the Exposome: How Far Have We Gone?

Around two-thirds of chronic human disease can not be explained by genetics alone. The Lancet Commission on Pollution and Health estimates that 16% of global premature deaths are linked to pollution. Additionally, it is now thought that humankind has surpassed the safe planetary operating space for introducing human-made chemicals into the Earth System. Direct and indirect exposure to a myriad of chemicals, known and unknown, poses a significant threat to biodiversity and human health, from vaccine efficacy to the rise of antimicrobial resistance as well as autoimmune diseases and mental health disorders. The exposome chemical space remains largely uncharted due to the sheer number of possible chemical structures, estimated at over 1060 unique forms. Conventional methods have cataloged only a fraction of the exposome, overlooking transformation products and often yielding uncertain results. In this Perspective, we have reviewed the latest efforts in mapping the exposome chemical space and its subspaces. We also provide our view on how the integration of data-driven approaches might be able to bridge the identified gaps.

Analysis of chemical contaminants in fish using high resolution mass spectrometry - A review

High resolution mass spectrometry (HRMS) has become an important tool in environmental and food safety analysis. This review highlights how HRMS has been used to analyze chemical contaminants in fish. Measuring and documenting chemical contaminants in fish serves not only as an indicator of environmental conditions but can also monitor the health of these animals and help protect an important source of human food. The incidence and significance of contaminants including veterinary drugs, human drugs and personal care products, pesticides, persistent organic pollutants, per- and poly fluorinated substances, and marine toxins will be reviewed. The advantage of HRMS over traditional MS is its ability to expand the number of compounds that can be detected and identified. This is true whether HRMS is used for targeted analytes, or more broadly for suspect screening and nontargeted analyses. The classes of compounds, types of fish or seafood, options for data acquisition and analysis, and reports of unexpected findings from recent HMRS methods for chemical contaminants in fish are summarized.

Endocrine disrupting chemicals in children's and their parents' urine: Is the exposure related to the Chinese and Western lifestyle?

Children are known to be more vulnerable to exposure to endocrine-disrupting chemicals (EDCs) compared to adults, but evaluating the exposure pathways can be challenging. This research employed target and non-target analysis (NTA) to examine the exposure characteristics of EDCs in spot urine samples collected from 46 children's (aged 3-12 years) and their parents in Hong Kong (Chinese/Western lifestyle) and Guangzhou (mainly Chinese lifestyle). The results revealed that the geometric mean concentrations of phthalate esters metabolites (mPAEs) and bisphenols (BPs) in children's urine were 127.3 μg/gcrea and 2.5 μg/gcrea in Guangzhou, and 93.7 μg/gcrea and 2.9 μg/gcrea in Hong Kong, respectively, which were consistent with global levels. NTA identified a total of 1069 compounds, including 106 EDCs, commonly detected in food, cosmetics, and drugs. Notable regional differences were observed between Guangzhou and Hong Kong with potential sources of EDCs including dietary and cosmetic additives, toys, flooring and dust, as well as differences in lifestyles, diet, and living environment. However, age was found to significantly impact EDC exposure. The quantified EDCs (mPAEs and BPs) posed possible health risks to 60% of the children. Moreover, the presence of caffeine in children's urine, which exhibited higher detection rates in children from Hong Kong (95.6%) and Guangzhou (44.4%), warrants further attention. The sources of EDCs exposure in these regions need to be fully confirmed.

Residual behavior of dinotefuran and its metabolites during Huangjiu fermentation and their effects on flavor

Yellow rice wine (Huangjiu) is a traditional Chinese alcoholic beverage. However, there is a risk of pesticide residues in Huangjiu due to pesticide indiscriminate use. In this study, the residues of dinotefuran and its metabolites during Huangjiu fermentation and their effects on flavor substances were studied. The initial concentrations of dinotefuran ranged from 856.3 to 1874.9 μg/L, and its half-life was no more than 3.65 d. At 24 d of Huangjiu fermentation, the terminal residues of dinotefuran, 1-methyl-3-(tetrahydro-3-furylmethyl)urea (UF) and 1-methyl-3-(tetrahydro-3-furylmethyl)guanidine (DN) were 195.1-535.3 μg/L, 38.33-48.70 μg/L and 37.8-74.1 μg/L, respectively. Twenty potential degradation compounds were identified by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS), and their toxicity was evaluated. Finally, the effect of dinotefuran on physicochemical properties and total phenol content of Huangjiu were analyzed. The risk of rancidity was significantly increased and bitter amino acids were formed. These findings provide a guidance and the safe production of Huangjiu.

Advanced oxidation processes for water and wastewater treatment - Guidance for systematic future research

Advanced oxidation processes (AOPs) are a growing research field with a large variety of different process variants and materials being tested at laboratory scale. However, despite extensive research in recent years and decades, many variants have not been transitioned to pilot- and full-scale operation. One major concern are the inconsistent experimental approaches applied across different studies that impede identification, comparison, and upscaling of the most promising AOPs. The aim of this tutorial review is to streamline future studies on the development of new solutions and materials for advanced oxidation by providing guidance for comparable and scalable oxidation experiments. We discuss recent developments in catalytic, ozone-based, radiation-driven, and other AOPs, and outline future perspectives and research needs. Since standardized experimental procedures are not available for most AOPs, we propose basic rules and key parameters for lab-scale evaluation of new AOPs including selection of suitable probe compounds and scavengers for the measurement of (major) reactive species. A two-phase approach to assess new AOP concepts is proposed, consisting of (i) basic research and proof-of-concept (technology readiness levels (TRL) 1-3), followed by (ii) process development in the intended water matrix including a cost comparison with an established process, applying comparable and scalable parameters such as UV fluence or ozone consumption (TRL 3-5). Subsequent demonstration of the new process (TRL 6-7) is briefly discussed, too. Finally, we highlight important research tools for a thorough mechanistic process evaluation and risk assessment including screening for transformation products that should be based on chemical logic and combined with complementary tools (mass balance, chemical calculations).

Target and Suspect Screening for Organic Additives in Six Classifications of Personal Care Products Using Liquid Chromatography-High-Resolution Mass Spectrometry

Personal care products (PCPs) are integral components of daily human existence, including a large number of chemicals intentionally added for functional attributes (e.g., preservatives and fragrances) or unintentionally present, such as plasticizers. This investigation aimed to optimize the methodology for target and suspect screening via liquid chromatography-high-resolution mass spectrometry, focusing on nine prevalent organic additives (comprising bisphenols A, F, and S, methyl, ethyl, propyl, and butylparaben, 5-chloro-2-methyl-4-isothiazolin-3-one, and 4-hydroxybenzoic acid). A total of 50 high-selling PCPs were purchased from the local online market as samples. In detail, PCP samples were classified into body washes, shampoos, hair conditioners, facial cleansers, body lotions, and moisture creams. For calibration, the quality assurance and quality control results demonstrated a coefficient of determination (R2) surpassing 0.999, with detection and quantification limits ranging from 2.5 to 100.0 ng/g. For recovery experiments, replicate recoveries (n = 5) ranged from 61 to 134%. In purchased PCP samples, five of the nine target compounds were detected via a target screening. Methylparaben exhibited the highest concentration (7860 mg/kg) in a facial cleanser, which is known as an endocrine-disrupting chemical. A total of 248 suspects of organic additives were screened in PCPs, leading to a tentative identification of 9. Confirmation (confidence level 1) via reference standards was achieved for three suspects, while six were tentatively identified with a confidence level of 2. This two-step extraction methodology utilizing methyl tert-butyl ether and isopropyl alcohol enabled simultaneous analysis of diverse chemical groups with distinct properties.

Emerging contaminants in water environments: progress, evolution, and prospects

This article employs bibliometric tools like VOSviewer, Bibliometrix, and CiteSpace for a comprehensive visual analysis of 1,612 documents on Emerging Contaminants in Waters from the Web of Science database. The objective is to elucidate the historical development, research hotspots, and trends in international studies of this field, offering valuable insights and guidance for future research directions. The analysis reveals a consistent increase in publications from 2003 to 2023, with the United States, China, and Spain being the most prolific contributors. A detailed examination of keyword co-occurrence and cluster analysis shows a predominant focus on themes such as pollutant detection, risk assessment, and biogeochemical cycling. Furthermore, the study underscores the significance of forming interdisciplinary networks among authors and institutions, highlighting its critical role in enhancing the quality and innovation of scientific research. The findings of this study not only chart the progression and focal points of research in this domain but also underscore the pivotal role of international collaboration, serving as an indispensable reference for shaping future research trajectories and fostering global cooperation.

Pesticide residues in animal-derived food: Current state and perspectives

Pesticides are widely used in the cultivation and breeding of agricultural products all over the world. However, their direct use or indirect pollution in animal breeding may lead to residual accumulation, migration, and metabolism in animal-derived foods, posing potential health risks to humans through the food chain. Therefore, it is necessary to detect pesticide residues in animal-derived food using simple, reliable, and sensitive methods. This review summarizes sample extraction and clean-up methods, as well as the instrumental determination technologies such as chromatography and chromatography-mass spectrometry for residual analysis in animal-derived foods, including meat, eggs and milk. Additionally, we perspectives on the future of this field. This information aims to assist relevant researchers in this area, contribute to the development of ideas and novel technical methods for residual detection, metabolic research and risk assessment of pesticides in animal-derived food.

Unveiling intricate transformation pathways of emerging contaminants during wastewater treatment processes through simplified network analysis

As the key stage for purifying wastewater, elimination of emerging contaminants (ECs) is found to be fairly low in wastewater treatment plants (WWTPs). However, less knowledge is obtained regarding the transformation pathways between various chemical structures of ECs under different treatment processes. This study unveiled the transformation pathways of ECs with different structures in 15 WWTPs distributed across China by simplified network analysis (SNA) we proposed. After treatment, the molecular weight of the whole component of wastewater decreased and the hydrophilicity increased. There are significant differences in the structure of eliminated, consistent and formed pollutants. Amino acids, peptides, and analogues (AAPAs) were detected most frequently and most removable. Benzenoids were refractory. Triazoles were often produced. The high-frequency reactions in different WWTPs were similar, (de)methylation and dehydration occurred most frequently. Different biological treatment processes performed similarly, while some advanced treatment processes differed, such as a significant increase of -13.976 (2HO reaction) paired mass distances (PMDs) in the chlorine alone process. Further, the common structural transformation was uncovered. 4 anti-hypertensive drugs, including irbesartan, valsartan, olmesartan, and losartan, were identified, along with 22 transformation products (TPs) of them. OH2 and H2O PMDs occurred most frequently and in 80.81 % of the parent-transformation product pairs, the intensity of the product was higher than parent in effluents, whose risk should be considered in future assessment activity. Together our results provide a macrography perspective on the transformation processes of ECs in WWTPs. In the future, selectively adopting wastewater treatment technology according to structures is conductive for eliminating recalcitrant ECs in WWTPs.

Contaminants of emerging concern: Occurrence, analytical techniques, and removal with electrochemical advanced oxidation processes with special emphasis in Latin America

The occurrence of contaminants of emerging concern (CECs) in environmental systems is gradually more studied worldwide. However, in Latin America, the presence of contaminants of emerging concern, together with their environmental and toxicological impacts, has recently been gaining wide interest in the scientific community. This paper presents a critical review about the source, fate, and occurrence of distinct emerging contaminants reported during the last two decades in various countries of Latin America. In recent years, Brazil, Chile, and Colombia are the main countries that have conducted research on the presence of these pollutants in biological and aquatic compartments. Data gathered indicated that pharmaceuticals, pesticides, and personal care products are the most assessed CECs in Latin America, being the most common compounds the followings: atrazine, acenaphthene, caffeine, carbamazepine, ciprofloxacin, diclofenac, diuron, estrone, losartan, sulfamethoxazole, and trimethoprim. Most common analytical methodologies for identifying these compounds were HPLC and GC coupled with mass spectrometry with the potential to characterize and quantify complex substances in the environment at low concentrations. Most CECs' monitoring and detection were observed near to urban areas which confirm the out-of-date wastewater treatment plants and sanitization infrastructures limiting the removal of these pollutants. Therefore, the implementation of tertiary treatment should be required. In this tenor, this review also summarizes some studies of CECs removal using electrochemical advanced oxidation processes that showed satisfactory performance. Finally, challenges, recommendations, and future perspectives are discussed.

OPEs-ID: A software for non-targeted screening of organophosphate esters based on liquid chromatography-high-resolution mass spectrometry

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers, presenting a potential threat to the environment and human health. To date, no automatic software exists for the nontargeted screening of OPEs. In this study, OPEs-ID, a user-friendly software, was developed for the identification of OPEs using liquid chromatography-high-resolution mass spectrometry. The main workflow of OPEs-ID included fragments-dependent precursor ion screening, elemental composition determination, extracted ion chromatograms (EIC) comparison, and molecular structure identification via MetFrag strategy. A mixture of 17 OPE standards was identified with an identification rate of 100% by OPEs-ID. OPEs-ID demonstrated a rate of 94.1% for correctly ranking within the top 1 candidate in a local database (41.2% in PubChem) for the 17 OPE standards, which remarkably improved the identification when compared to conventional in silico fragmentation algorithms. Using a pooled airborne fine particle sample (PM2.5), OPEs-ID could automatically retrieve 22 valid molecules with structure candidates. The detection frequencies of 9 newly identified OPEs were between 13% and 100% in the 32 PM2.5 samples. Their semi-quantification concentrations were comparable to those of some traditional OPEs. Overall, OPEs-ID offers a powerful tool to significantly enrich our understanding of the OPEs present in the environment.

Compound Similarity Network as a Novel Data Mining Strategy for High-Throughput Investigation of Degradation Pathways of Organic Pollutants in Industrial Wastewater Treatment

Identification of degradation products and pathways is crucial for investigating emerging pollutants and evaluation of wastewater treatment methods. Nontargeted analysis is a powerful tool to comprehensively investigate the degradation pathways of organic pollutants in real-world wastewater samples but often generates large data sets, making it difficult to effectively locate the exact information on interests. Herein, to efficiently establish the linkages among compounds in the same degradation pathways, we introduce a compound similarity network (CSN) as a novel data mining strategy for LC-MS-based nontargeted analysis of complex wastewater samples. Different from molecular networks that cluster compounds based on MS/MS spectra similarity, our CSN strategy harnesses molecular fingerprints to establish linkages among compounds and thus is spectra-independent. The effectiveness of CSN was demonstrated by nontargeted identification of degradation pathways and products of organic pollutants in leather industrial wastewater that underwent laboratory-scale activated carbon adsorption (ACD) and ozonation treatments. Utilizing CSN in interpreting nontargeted data, we tentatively annotated 4324 compounds in the untreated leather industrial wastewater, 3246 after ACD, and 3777 after ACD/ozonation. We located 145 potential degradation pathways of organic pollutants in the ACD/ozonation process using CSN and validated 7 pathways with 15 chemical standards. CSN also revealed 5 clusters of emerging pollutants, from which 3 compounds were selected for in vitro cytotoxicity study to evaluate their potential biohazards as new pollutants. As CSN offers an efficient way to connect massive compounds and to find multiple degradation pathways in a high-throughput manner, we anticipate that it will find wide applications in nontargeted analysis of diverse environmental samples.

Establishing performance metrics for quantitative non-targeted analysis: a demonstration using per- and polyfluoroalkyl substances

Non-targeted analysis (NTA) is an increasingly popular technique for characterizing undefined chemical analytes. Generating quantitative NTA (qNTA) concentration estimates requires the use of training data from calibration "surrogates," which can yield diminished predictive performance relative to targeted analysis. To evaluate performance differences between targeted and qNTA approaches, we defined new metrics that convey predictive accuracy, uncertainty (using 95% inverse confidence intervals), and reliability (the extent to which confidence intervals contain true values). We calculated and examined these newly defined metrics across five quantitative approaches applied to a mixture of 29 per- and polyfluoroalkyl substances (PFAS). The quantitative approaches spanned a traditional targeted design using chemical-specific calibration curves to a generalizable qNTA design using bootstrap-sampled calibration values from "global" chemical surrogates. As expected, the targeted approaches performed best, with major benefits realized from matched calibration curves and internal standard correction. In comparison to the benchmark targeted approach, the most generalizable qNTA approach (using "global" surrogates) showed a decrease in accuracy by a factor of ~4, an increase in uncertainty by a factor of ~1000, and a decrease in reliability by ~5%, on average. Using "expert-selected" surrogates (n = 3) instead of "global" surrogates (n = 25) for qNTA yielded improvements in predictive accuracy (by ~1.5×) and uncertainty (by ~70×) but at the cost of further-reduced reliability (by ~5%). Overall, our results illustrate the utility of qNTA approaches for a subclass of emerging contaminants and present a framework on which to develop new approaches for more complex use cases.

Hydroxylated transformation products of pharmaceutical active compounds: Generation from processes used in wastewater treatment plants and its environmental monitoring

Pharmaceutical active compounds (PhACs) are organic pollutants detected in wastewater and aquatic environments worldwide in concentrations ranging from ng L-1 to μg L-1. Wastewater effluents containing PhACs residues is discharged in municipal sewage and, subsequently collected in municipal wastewater treatment plants (WWTPs) where are not entirely removed. Thus, PhACs and its transformation products (TPs) are discharged into water bodies. In the current work, the transformation of PhACs under treatments used in municipal WWTPs such as biological, photolysis, chlorination, and ozonation processes was reviewed. Data set of the major transformation pathways were obtained of studies that performed the PhACs removal and TPs monitoring during batch-scale experiments using gas and liquid chromatography coupled with tandem mass spectrometry (GC/LC-MS/MS). Several transformation pathways as dealkylation, hydroxylation, oxidation, acetylation, aromatic ring opening, chlorination, dehalogenation, photo-substitution, and ozone attack reactions were identified during the transformation of PhACs. Especially, hydroxylation reaction was identified as transformation pathway in all the processes. During the elucidation of hydroxylated TPs several isobaric compounds as monohydroxylated and dihydroxylated were identified. However, hydroxylated TPs monitoring in wastewater and aquatic environments is a topic scarcely studied due to that has no environmental significance, lack of available analytic standars of hydroxylated TPs and lack of analytic methods for their identification. Thus, screening strategy for environmental monitoring of hydroxylated TPs was proposed through target and suspect screening using GC/LC-MS/MS systems. In the next years, more studies on the hydroxylated TPs monitoring are necessary for its detection in WWTPs effluents as well as studies on their environmental effects in aquatic environments.

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.

A comprehensive insight into the transformation pathways and products of fluoxetine and venlafaxine in wastewater based on molecular networking nontarget screening

Fluoxetine (FLX) and venlafaxine (VEN) are widely used antidepressant pharmaceuticals and were frequently detected in wastewater. Despite incomplete mineralization during biological wastewater treatment processes has been revealed, little is known about their transformation products (TPs) formed in the biological systems. To fill this gap, batch reactors and molecular networking nontarget screening were employed to identify the TPs and explore the transformation pathways of FLX and VEN in wastewater. On the basis, the concentrations of the TPs in wastewater treatment plants (WWTPs) were determined and their toxicity was predicted. The removal rate constants per unit of biomass of FLX and VEN were up to 0.3192 and 0.1644 L/(gMLSS*d) in batch experiments, respectively. Subsequently, 11 TPs of VEN and 11 TPs of FLX were tentatively identified, among which 9 TPs of FLX and 5 TPs of VEN were newly reported in this study. The proposed transformation pathways provided new insights into the transformation reactions including dehydrogenation, N-formylation and hydroxylation for FLX, and formylation, epoxidation and methylation for VEN. Particularly, N-succinylation and demethylation were the dominant transformation pathways for FLX and VEN during transformation processes. The results of sampling campaigns revealed that the accumulated concentration of TPs were higher than the concentrations of VEN in effluent of WWTPs. In silico prediction results suggested that certain TPs have higher toxicity, persistence and biodegradability than their corresponding parent compounds of FLX and VEN. In addition, VEN-TP264(a) showed higher ecological risks than VEN. This study revealed the transformation processes and fate of FLX and VEN in wastewater, indicating that greater concerns should be exerted on the toxicity detection and control of the TPs of FLX and VEN in the treated wastewater.

Assessing the transformation products and fate of Oxytetracycline by simulated aerobic degradation tests

Oxytetracycline (OTC) is a widely used broad-spectrum antibiotic, whose presence in water and sediments was reported in various regions of the world. The effects of OTC and other tetracyclines on the environment have been intensively studied although many of their transformation products (TPs) formed in the environment and their impact have not been yet fully characterized. Abiotic and biotic degradation tests under aerobic conditions at two pH values were carried out using OTC in artificial water/sediment systems to assess the effect of these variables on the environmental fate of the pollutant. HPLC-MSn was employed to detect and identify the main degradation products and pathways. Several transformations involved in the process were identified including alcohol oxidation, decarbonylation and hydroxylation. Differences in TPs and kinetics were found among degradation conditions, remarking a faster degradation of both OTC and TPs in the presence of microorganisms and at lower pH values. In summary, a total of 44 TPs were detected and structures were proposed for 20 of them, none of them having been previously reported. Furthermore, OTC degradation generated 24 TPs which remained in either solution or sediment, although none of them displayed higher algae toxicity than OTC. These results might be useful for planning future remediation and monitoring strategies.

Suspect and Nontarget Screening Reveal the Underestimated Risks of Antibiotic Transformation Products in Wastewater Treatment Plant Effluents

Antibiotics are anthropogenic contaminants with a global presence and of deep concern in aquatic environments, while less is known about the occurrence and risks of their transformation products (TPs). Herein, we developed a comprehensive suspect and nontarget screening workflow based on high-resolution mass spectrometry to identify unknown antibiotic TPs in wastewater treatment plant effluents. We identified 211 compounds (35 parent antibiotics and 176 TPs) at confidence levels of ≥3 and 107 TPs originated from macrolides. TPs were quantified by 17 TPs standards and semiquantified by the predicted response factors and accounted for 55.6-95.1% (76.7% on average) of the total concentrations of parents and TPs. 22.2%, 63.1%, and 18.8% of the identified TPs were estimated to be more persistent, mobile, and toxic than their parent antibiotics, respectively. Further ecological risk assessment based on concentrations and toxicity to aquatic organisms revealed that the cumulative risks of TPs were generally higher than those of parents. Despite the newly formed N-oxide TPs, the tertiary treatment process (mainly ozonation) could decrease the averaged 20.3% of concentrations and 36.2% of the risks of antibiotic-related compounds. This study highlights the necessity to include antibiotic TPs in environmental scrutiny and risk assessment of antibiotics in different aquatic environments.

Electrochemistry-mass spectrometry bridging the gap between suspect and target screening of valsartan transformation products in wastewater treatment plant effluent

Degradation of xenobiotics in wastewater treatment plants may lead to the formation of transformation products with higher persistence or increased (eco-)toxic potential compared to the parent compounds. Accordingly, the identification of transformation products from wastewater treatment plant effluents has gained increasing attention. Here, we show the potential of electrochemistry hyphenated to liquid chromatography and mass spectrometry for the prediction of oxidative degradation in wastewater treatment plants using the antihypertensive drug valsartan as a model compound. This approach identifies seven electrochemical transformation products of valsartan, which are used to conduct a suspect screening in effluent of the main wastewater treatment plant in the city of Münster in Germany. Apart from the parent compound valsartan, an electrochemically predicted transformation product, the N-dealkylated ETP336, is detected in wastewater treatment plant effluent. Subsequently, a targeted liquid chromatographytandem mass spectrometry method for the detection of valsartan and its electrochemical transformation products is set up. Here, electrochemical oxidation is used to generate reference materials of the transformation products in situ by hyphenating electrochemistry online to a triple quadrupole mass spectrometer. Using this setup, multiple reaction monitoring transitions are set up without the need for laborious and costly synthesis and isolation of reference materials for the transformation products. The targeted method is then applied to extracts from wastewater treatment plant effluent and the presence of ETP336 and valsartan in the samples is verified. The presented workflow can be used to set up targeted analysis methods for previously unknown transformation products even without the need for expensive high-resolution mass spectrometers.

An AI-powered patient triage platform for future viral outbreaks using COVID-19 as a disease model

Over the last century, outbreaks and pandemics have occurred with disturbing regularity, necessitating advance preparation and large-scale, coordinated response. Here, we developed a machine learning predictive model of disease severity and length of hospitalization for COVID-19, which can be utilized as a platform for future unknown viral outbreaks. We combined untargeted metabolomics on plasma data obtained from COVID-19 patients (n = 111) during hospitalization and healthy controls (n = 342), clinical and comorbidity data (n = 508) to build this patient triage platform, which consists of three parts: (i) the clinical decision tree, which amongst other biomarkers showed that patients with increased eosinophils have worse disease prognosis and can serve as a new potential biomarker with high accuracy (AUC = 0.974), (ii) the estimation of patient hospitalization length with ± 5 days error (R2 = 0.9765) and (iii) the prediction of the disease severity and the need of patient transfer to the intensive care unit. We report a significant decrease in serotonin levels in patients who needed positive airway pressure oxygen and/or were intubated. Furthermore, 5-hydroxy tryptophan, allantoin, and glucuronic acid metabolites were increased in COVID-19 patients and collectively they can serve as biomarkers to predict disease progression. The ability to quickly identify which patients will develop life-threatening illness would allow the efficient allocation of medical resources and implementation of the most effective medical interventions. We would advocate that the same approach could be utilized in future viral outbreaks to help hospitals triage patients more effectively and improve patient outcomes while optimizing healthcare resources.

Bypassing the Identification: MS2Quant for Concentration Estimations of Chemicals Detected with Nontarget LC-HRMS from MS2 Data

Nontarget analysis by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) is now widely used to detect pollutants in the environment. Shifting away from targeted methods has led to detection of previously unseen chemicals, and assessing the risk posed by these newly detected chemicals is an important challenge. Assessing exposure and toxicity of chemicals detected with nontarget HRMS is highly dependent on the knowledge of the structure of the chemical. However, the majority of features detected in nontarget screening remain unidentified and therefore the risk assessment with conventional tools is hampered. Here, we developed MS2Quant, a machine learning model that enables prediction of concentration from fragmentation (MS2) spectra of detected, but unidentified chemicals. MS2Quant is an xgbTree algorithm-based regression model developed using ionization efficiency data for 1191 unique chemicals that spans 8 orders of magnitude. The ionization efficiency values are predicted from structural fingerprints that can be computed from the SMILES notation of the identified chemicals or from MS2 spectra of unidentified chemicals using SIRIUS+CSI:FingerID software. The root mean square errors of the training and test sets were 0.55 (3.5×) and 0.80 (6.3×) log-units, respectively. In comparison, ionization efficiency prediction approaches that depend on assigning an unequivocal structure typically yield errors from 2× to 6×. The MS2Quant quantification model was validated on a set of 39 environmental pollutants and resulted in a mean prediction error of 7.4×, a geometric mean of 4.5×, and a median of 4.0×. For comparison, a model based on PaDEL descriptors that depends on unequivocal structural assignment was developed using the same dataset. The latter approach yielded a comparable mean prediction error of 9.5×, a geometric mean of 5.6×, and a median of 5.2× on the validation set chemicals when the top structural assignment was used as input. This confirms that MS2Quant enables to extract exposure information for unidentified chemicals which, although detected, have thus far been disregarded due to lack of accurate tools for quantification. The MS2Quant model is available as an R-package in GitHub for improving discovery and monitoring of potentially hazardous environmental pollutants with nontarget screening.

Combining predictive and analytical methods to elucidate pharmaceutical biotransformation in activated sludge

While man-made chemicals in the environment are ubiquitous and a potential threat to human health and ecosystem integrity, the environmental fate of chemical contaminants such as pharmaceuticals is often poorly understood. Biodegradation processes driven by microbial communities convert chemicals into transformation products (TPs) that may themselves have adverse ecological effects. The detection of TPs formed during biodegradation has been continuously improved thanks to the development of TP prediction algorithms and analytical workflows. Here, we contribute to this advance by (i) reviewing past applications of TP identification workflows, (ii) applying an updated workflow for TP prediction to 42 pharmaceuticals in biodegradation experiments with activated sludge, and (iii) benchmarking 5 different pathway prediction models, comprising 4 prediction models trained on different datasets provided by enviPath, and the state-of-the-art EAWAG pathway prediction system. Using the updated workflow, we could tentatively identify 79 transformation products for 31 pharmaceutical compounds. Compared to previous works, we have further automatized several steps that were previously performed by hand. By benchmarking the enviPath prediction system on experimental data, we demonstrate the usefulness of the pathway prediction tool to generate suspect lists for screening, and we propose new avenues to improve their accuracy. Moreover, we provide a well-documented workflow that can be (i) readily applied to detect transformation products in activated sludge and (ii) potentially extended to other environmental studies.

European Chemicals Agency (ECHA) and European Food Safety Authority (EFSA), Hofman‐Caris R, Dingemans M, Reus A, Shaikh SM, Muñoz Sierra J, Karges U, der Beek TA, Nogueiro E, Lythgo C, Parra Morte JM, Bastaki M, Serafimova R, Friel A, Court Marques D, Uphoff A, Bielska L, Putzu C, Ruggeri L, Papadaki P. Guidance document on the impact of water treatment processes on residues of active substances or their metabolites in water abstracted for the production of drinking water

This guidance document provides a tiered framework for risk assessors and facilitates risk managers in making decisions concerning the approval of active substances (AS) that are chemicals in plant protection products (PPPs) and biocidal products, and authorisation of the products. Based on the approaches presented in this document, a conclusion can be drawn on the impact of water treatment processes on residues of the AS or its metabolites in surface water and/or groundwater abstracted for the production of drinking water, i.e. the formation of transformation products (TPs). This guidance enables the identification of actual public health concerns from exposure to harmful compounds generated during the processing of water for the production of drinking water, and it focuses on water treatment methods commonly used in the European Union (EU). The tiered framework determines whether residues from PPP use or residues from biocidal product use can be present in water at water abstraction locations. Approaches, including experimental methods, are described that can be used to assess whether harmful TPs may form during water treatment and, if so, how to assess the impact of exposure to these water treatment TPs (tTPs) and other residues including environmental TPs (eTPs) on human and domesticated animal health through the consumption of TPs via drinking water. The types of studies or information that would be required are described while avoiding vertebrate testing as much as possible. The framework integrates the use of weight-of-evidence and, when possible alternative (new approach) methods to avoid as far as possible the need for additional testing.

Degradation of the Novel Heterocyclic Insecticide Pyraquinil in Water: Kinetics, Degradation Pathways, Transformation Products Identification, and Toxicity Assessment

As new pesticides are continuously introduced into agricultural systems, it is essential to investigate their environmental behavior and toxicity effects to better evaluate their potential risks. In this study, the degradation kinetics, pathways, and aquatic toxicity of the new fused heterocyclic insecticide pyraquinil in water under different conditions were investigated for the first time. Pyraquinil was classified as an easily degradable pesticide in natural water, and hydrolyzes faster in alkaline conditions and at higher temperatures. The formation trends of the main transformation products (TPs) of pyraquinil were also quantified. Fifteen TPs were identified in water using ultrahigh-performance liquid chromatography coupled to quadrupole Orbitrap high-resolution mass spectrometry (UHPLC-Orbitrap-HRMS) and Compound Discoverer software, which adopted suspect and nontarget screening strategies. Among them, twelve TPs were reported for the first time and 11 TPs were confirmed by synthesis of their standards. The proposed degradation pathways have demonstrated that the 4,5-dihydropyrazolo[1,5-a]quinazoline skeleton of pyraquinil is stable enough to retain in its TPs. ECOSAR prediction and laboratory tests showed that pyraquinil was "very toxic" or "toxic" to aquatic organisms, while the toxicities of all of the TPs are substantially lower than that of pyraquinil except for TP484, which was predicted to pose a higher toxicity. The results are important for elucidating the fate and assessing the environmental risks of pyraquinil, and provide guidance for scientific and reasonable use.

Novel nontarget LC-HRMS-based approaches for evaluation of drinking water treatment

A conventional evaluation methodology for drinking water pollution focuses on analysing hundreds of compounds, usually by liquid chromatography-tandem mass spectrometry. High-resolution mass spectrometry allows comprehensive evaluation of all detected signals (compounds) based on their elemental composition, intensity, and numbers. We combined target analysis of 192 emerging micropollutants with nontarget (NT) full-scan/MS/MS methods to describe the impact of treatment steps in detail and assess drinking water treatment efficiency without compound identification. The removal efficiency based on target analytes ranged from - 143 to 97%, depending on the treatment section, technologies, and season. The same effect calculated for all signals detected in raw water by the NT method ranged between 19 and 65%. Ozonation increased the removal of micropollutants from the raw water but simultaneously caused the formation of new compounds. Moreover, ozonation byproducts showed higher persistence than products formed during other types of treatment. We evaluated chlorinated and brominated organics detected by specific isotopic patterns within the developed workflow. These compounds indicated anthropogenic raw water pollution but also potential treatment byproducts. We could match some of these compounds with libraries available in the software. We can conclude that passive sampling combined with nontargeted analysis shows to be a promising approach for water treatment control, especially for long-term monitoring of changes in technology lines because passive sampling dramatically reduces the number of samples and provides time-weighted average information for 2 to 4 weeks.

Revealing specific transformation pattern of sulfonamides during wastewater biological treatment processes by molecular networking nontarget screening

Biotransformation of emerging contaminants (ECs) is of importance in various natural and engineered systems to eliminate the adverse effects of ECs toward organisms. In wastewater, structurally similar ECs may transform through similar reactions triggered by common enzymes. However, the transformation pattern for them was scarcely studied. To fill the research gaps, five sulfonamides were chosen as the targeted ECs with similar structure to explore the transformation pattern in wastewater biological treatment experiments at lab scale. Through molecular networking based nontarget screening, 45 transformation products (TPs) of sulfonamides were identified and 14 of them were newly found. On the basis, five specific transformation patterns were summarized for sulfonamides by transformation pathways comparing, reaction frequency analyzing and dominant TPs comparing. Results suggested that pterin-chelation and formylation (dominant transformation pathway) and acetylation, methylation and deamination reactions were commonly occurred for sulfonamides in wastewater. Among them, the role of formylation as the dominant transformation pathway for sulfonamides transformed in wastewater was firstly reported in present study. Subsequent frontier molecular orbital calculation suggested the active site of amino (N₁H₂-) may contribute the specific transformation pattern of sulfonamides. Present study reveals the specific transformation pattern of sulfonamides from the aspect of TPs and transformation pathways. In the future, knowledge on the specific transformation pattern can be used to regulate and enhance the removal of a class of ECs with similar structure rather than just one of ECs.

Abiotic transformation of kresoxim-methyl in aquatic environments: Structure elucidation of transformation products by LC-HRMS and toxicity assessment

In this study, abiotic transformation of an important strobilurin fungicide, kresoxim-methyl, was investigated under controlled laboratory conditions for the first time by studying its kinetics of hydrolysis and photolysis, degradation pathways and toxicity of possibly formed transformation products (TPs). The results indicated that kresoxim-methyl showed a fast degradation in pH9 solutions with DT₅₀ of 0.5 d but relatively stable under neutral or acidic environments in the dark. It was prone to photochemical reactions under simulated sunlight, and the photolysis behavior was easily affected by different natural substances such as humic acid (HA), Fe³⁺and NO₃^-which are ubiquitous in natural water, showing the complexity of degradation mechanisms and pathways of this chemical compound. The potential multiple photo-transformation pathways via photoisomerization, hydrolyzation of methyl ester, hydroxylation, cleavage of oxime ether and cleavage of benzyl ether were observed. 18 TPs generated from these transformations were structurally elucidated based on an integrated workflow combining suspect and nontarget screening by high resolution mass spectrum (HRMS), and two of them were confirmed with reference standards. Most of TPs, as far as we know, have never been described before. The in-silico toxicity assessment showed that some of TPs were still toxic or very toxic to aquatic organisms, although they exhibit lower aquatic toxicity compared to the parent compound. Therefore, the potential hazards of the TPs of kresoxim-methyl merits further evaluation.

Nontarget screening based on molecular networking strategy to identify transformation products of citalopram and sertraline in wastewater

Citalopram (CIT) and sertraline (SER) are highly consumed antidepressants worldwide and have been extensively detected in wastewater. Due to the incomplete mineralization, transformation products (TPs) of them can be detected in wastewater. Comparing with parent compounds, knowledge on TPs are limited. To fill these research gaps, lab-scale batch experiments, WWTPs sampling and in silico toxicity prediction were implemented to investigate the structure, occurrence and toxicity of TPs. Based on molecular networking nontarget strategy, 13 TPs of CIT and 12 TPs of SER were tentatively identified. Among them, 4 TPs from CIT and 5 TPs from SER were newly found in present study. TPs identification results compared with results obtained from previous nontarget strategies demonstrated that the excellent performances for molecular networking strategy on candidate TPs prioritizing and new TPs finding, especially for low abundance TPs. Further, transformation pathways for CIT and SER in wastewater were proposed. Newly identified TPs provided insights on defluorination, formylation and methylation for CIT and dehydrogenation, N-malonylation and N-acetoxylation for SER transformed in wastewater. Nitrile hydrolysis and N-succinylation were found to be the dominant transformation pathways for CIT and SER in wastewater, respectively. WWTPs sampling results shown the concentrations of SER and CIT ranged from 0.46 to 28.66 ng/L and 17.16 to 58.36 ng/L. In addition, 7 TPs of CIT and 2 TPs of SER found in lab-scale wastewater samples were found in WWTPs. In silico results suggested 2 TPs of CIT may be more toxic than CIT toward all three trophic levels organisms. Present study provides new insights into the transformation processes of CIT and SER in wastewater. In addition, the necessity of paying more attention on TPs was further highlighted from the aspects of toxicity for TPs of CIT and SER in effluent of WWTPs.

Mechanism of visible light enhances microbial degradation of Bisphenol A

Bisphenol A (BPA) is a toxic endocrine disruptor detected in various environments. Microbial metabolic/enzymatic degradation has been thought to be the main pathway for BPA attenuation in natural environments. In this study, we found that under visible light conditions, superoxide produced by bacteria was the main reason for the rapid removal of BPA, accounting for 57 % of the total removal rate. With visible light, the bacteria degraded BPA at a rate of 0.22 mg/L/d, and the total removal within 8 days reached 85 %, which is 4.7 times compared with that of dark culture. The intermediate product 4-iso-propenylphenol, which was considered as an end-product of microbial degradation of BPA in previous reports, was detected in large quantities at 24 h in culture but gradually decreased in our experiment. Community analysis suggested bacteria with aromatic hydrocarbon degradation ability were more enriched under light incubation. Moreover, the bacteria showed well degradation ability to various pharmaceutically active but nonbiodegradable compounds including diclofenac and fluoxetine, with a removal rate of 88 % and 20 %, respectively. Our study revealed the organic pollutant transformation pathway under the combined action of light and microorganisms, providing new insights into the microbial treatment of aromatic hydrocarbon pollutants.

Utility of a non-target screening method to explore the chlorination of similar sulfonamide antibiotics: Pathways and NCl intermediates

Sulfonamides (SAs) are ubiquitous antibiotics that are increasingly detected in aquatic environments and can react with free available chlorine to produce transformation products (TPs) during disinfection. However, the TPs generated during chlorination remains poorly understood. Here, a non-target screening method based on the PyHRMS program was used to assess the transformation pathways of five SAs, particularly the transient NCl intermediates, during a simulated chlorination process. We observed 210 TPs during SA chlorination using a non-target screening method based on high-resolution mass spectrometry, and the reaction mechanisms mainly included chlorine substitution, desulfonation, and hydroxylation. Among the TPs, 87 were tentatively proposed to be NCl intermediates as they instantly disappeared after quenching with Na₂S₂O₃. The MS² spectra of 13 of these potential NCl intermediates were obtained, and all displayed an [M-Cl]⁺ fragment. A diagnostic fragment ion (DFI) strategy was applied to explore the structural relationship between parent compounds and TPs. Based on the result, five SAs and 101 TPs (if their MS² spectra were available) could be connected through the same fragments, and this method was also proved effective in a real wastewater treatment plant effluent sample. We believe this novel method can help explore the TPs of organic compounds during chlorination in drinking water plants.

Understanding the biodegradation pathways of azo dyes by immobilized white-rot fungus, Trametes hirsuta D7, using UPLC-PDA-FTICR MS supported by in silico simulations and toxicity assessment

No biodegradation methods are absolute in the treatment of all textile dyes, which leads to structure-dependent degradation. In this study, biodegradation of three azo dyes, reactive black 5 (RB5), acid blue 113 (AB113), and acid orange 7 (AO7), was investigated using an immobilized fungus, Trametes hirsuta D7. The degraded metabolites were identified using UPLC-PDA-FTICR MS and the biodegradation pathway followed was proposed. RB5 (92%) and AB113 (97%) were effectively degraded, whereas only 30% of AO7 was degraded. Molecular docking simulations were performed to determine the reason behind the poor degradation of AO7. Weak binding affinity, deficiency in H-bonding interactions, and the absence of interactions between the azo (-NN-) group and active residues of the model laccase enzyme were responsible for the low degradation efficiency of AO7. Furthermore, cytotoxicity and genotoxicity assays confirmed that the fungus-treated dye produced non-toxic metabolites. The observations of this study will be useful for understanding and further improving enzymatic dye biodegradation.

Suspect Screening of Chemicals in Hospital Wastewaters Using Effect-Directed Analysis Approach as Prioritization Strategy

The increasing number of contaminants in the environment has pushed water monitoring programs to find out the most hazardous known and unknown chemicals in the environment. Sample treatment-simplification methods and non-target screening approaches can help researchers to not overlook potential chemicals present in complex aqueous samples. In this work, an effect-directed analysis (EDA) protocol using the sea urchin embryo test (SET) as a toxicological in vivo bioassay was used as simplified strategy to identify potential unknown chemicals present in a very complex aqueous matrix such as hospital effluent. The SET bioassay was used for the first time here to evaluate potential toxic fractions in hospital effluent, which were obtained after a two-step fractionation using C₁₈ and aminopropyl chromatographic semi-preparative columns. The unknown compounds present in the toxic fractions were identified by means of liquid chromatography coupled to a Q Exactive Orbitrap high-resolution mass spectrometer (LC-HRMS) and using a suspect analysis approach. The results were complemented by gas chromatography-mass spectrometry analysis (GC-MS) in order to identify the widest range of chemical compounds present in the sample and the toxic fractions. Using EDA as sample treatment simplification method, the number of unknown chemicals (>446 features) detected in the raw sample was narrowed down to 94 potential toxic candidates identified in the significantly toxic fractions. Among them, the presence of 25 compounds was confirmed with available chemical standards including 14 pharmaceuticals, a personal care product, six pesticides and four industrial products. The observations found in this work emphasize the difficulties in identifying potential toxicity drivers in complex water samples, as in the case of hospital wastewater.

Advanced throughput analytical strategies for the comprehensive HRMS screening of organic micropollutants in eggs of different bird species

Raptors are ideal indicators for biomonitoring studies using wildlife in order to assess the environmental pollution in the terrestrial ecosystem, since they are placed in the highest trophic position in the food webs and their life expectancy is relatively long. In this study, 26 eggs of 4 bird species (Peregrine falcon, Eurasian curlew, Little owl and Eagle owl) collected in Germany, were investigated for the presence of persistent organic pollutants (POPs) and thousands of contaminants of emerging concern (CECs). Generic sample preparation protocols were followed for the extraction of the analytes and the purification of the extracts, and the samples were analyzed both by liquid (LC) and gas chromatography (GC) coupled to high resolution mass spectrometry (HRMS), for capturing a wide range of organic micropollutants with different physicochemical properties. State-of-the-art screening methodologies were applied in the acquired HRMS data, including wide-scope target analysis of 2448 known pollutants and suspect screening of over 65,000 environmentally relevant compounds. Overall, 58 pollutants from different chemical classes, such as plant protection products, per- and polyfluoroalkyl substances and medicinal products, as well as their transformation products, were determined through target analysis. Most of the detected compounds were lipophilic (logP>2), although the presence of (semi)polar contaminants should not be overlooked, underlying the need for holistic analytical approaches in environmental monitoring studies. p,p'-DDE, PCB 153 and PCB138, PFOS and methylparaben were the most frequently detected compounds. 50 additional substances were identified and semi-quantified through suspect screening workflows, including mainly compounds of industrial use with high production volume.

Multiclass target analysis of contaminants of emerging concern including transformation products, soil bioavailability assessment and retrospective screening as tools to evaluate risks associated with reclaimed water reuse

The occurrence of 200 multiclass contaminants of emerging concern (CECs) encompassing 168 medicinal products and transformation products (TPs), 5 artificial sweeteners, 12 industrial chemicals, and 15 other compounds was investigated in influent and effluent wastewater samples collected during 7 consecutive days from 5 wastewater treatment plants (WWTPs) located in Cyprus. The methodology included a generic solid-phase extraction protocol using mixed-bed cartridges followed by Ultra-High Performance Liquid Chromatography coupled with Quadrupole-Time of Flight Mass Spectrometry (UHPLC-QTOF-MS) analysis. A total of 63 CECs were detected at least in one sample, with 52 and 55 out of the 200 compounds detected in influents and effluents, respectively. Ten (10) out of the 24 families of parent compounds and associated TPs were found in the wastewater samples (influent or effluent). 1-H-benzotriazole, carbamazepine, citalopram, lamotrigine, sucralose, tramadol, and venlafaxine (>80 % frequency of appearance in effluents) were assessed with respect to their bioavailability in soil as part of different scenarios of irrigation with reclaimed water following a qualitative approach. A high score of 12 (high probability) was predicted for 2 scenarios, a low score of 3 (rare occasions) for 2 scenarios, while the rest 28 scenarios had scores 5-8 (unlikely or limited possibility) and 9-11 (possibly). Retrospective screening was performed with the use of a target database of 2466 compounds and led to the detection of 158 additional compounds (medicinal products (65), medicinal products TPs (15), illicit drugs (7), illicit drugs TPs (3), industrial chemicals (11), plant protection products (25), plant protection products TPs (10), and various other compounds (22). This work aspires to showcase how the presence of CECs in wastewater could be investigated and assessed at WWTP level, including an expert-based methodology for assessing the soil bioavailability of CECs, with the aim to develop sustainable practices and enhance reclaimed water reuse.

Mass Spectrometric Methods for Non-Targeted Screening of Metabolites: A Future Perspective for the Identification of Unknown Compounds in Plant Extracts

Phyto products are widely used in natural products, such as medicines, cosmetics or as so-called “superfoods”. However, the exact metabolite composition of these products is still unknown, due to the time-consuming process of metabolite identification. Non-target screening by LC-HRMS/MS could be a technique to overcome these problems with its capacity to identify compounds based on their retention time, accurate mass and fragmentation pattern. In particular, the use of computational tools, such as deconvolution algorithms, retention time prediction, in silico fragmentation and sophisticated search algorithms, for comparison of spectra similarity with mass spectral databases facilitate researchers to conduct a more exhaustive profiling of metabolic contents. This review aims to provide an overview of various techniques and tools for non-target screening of phyto samples using LC-HRMS/MS.

Pesticides Identification and Sustainable Viticulture Practices to Reduce Their Use: An Overview

The use of pesticides is a necessary practice in the modern era. Therefore, it is impossible to ignore the pesticide market, which has developed into one of the most lucrative in the world. Nowadays, humans are subjected to many potential risks, and significant amounts of toxic compounds enter their bodies through food, drink, and the air itself. Identification and quantification of these hazardous compounds is crucial for the sustainable development of an increasing world population which poses high climatic and political constraints on agricultural production systems. The maximum residue limits for pesticides have been regulated by the Codex Alimentarius Commission and European Union to protect human health. In this review, we have summarized and explained the analytical methods for pesticide extraction and determination. Also, sustainable viticulture practices like organic vineyards, tillage, biopesticides, nanobiopesticides, and precision viticulture are briefly discussed. These new techniques allow wine growers to be more profitable and efficient, while contributing to the reduction of pests and increasing the quality of wines.

Further transformation of the primary ozonation products of tramadol- and venlafaxine N-oxide: Mechanistic and structural considerations

Ozonation has been used to effectively remove micropollutants from the secondary effluent in several wastewater treatment plants. It is known that ozonation transforms tertiary amine compounds into their respective N-oxides, however in an earlier study a mass balance could not be closed at elevated ozone concentrations, leading to the assumption that more ozonation products are possible. This study was conducted to elucidate which (hitherto unknown) ozonation products can be formed from venlafaxine and tramadol when ozonating wastewater. Ozonation experiments were performed with tramadol and venlafaxine N-oxide in two different set-ups. Both tramadol- and venlafaxine N-oxide degraded during ozonation in pure (deionized) water in both semi-continuous and batch mode ozonation set-ups. 13 and 17 new transformation products were detected from tramadol- and venlafaxine N-oxide respectively, using high resolution mass spectrometry with ESI(+) ionization. Empirical chemical formulas were proposed based on the determination of the exact masses and interpretation of the product ion spectra. These transformation products result from the addition of one to three oxygen atoms and removal of C, -CH₂, C₂H₂, C₃H₆, etc., from the parent molecule, respectively. Quenching experiments suggested that most of the transformation products originated from the direct reaction with ozone (eight for tramadol N-oxide and ten for venlafaxine N-oxide), whereas fewer products originated from the reaction with OH radicals (three for tramadol N-oxide and three for venlafaxine N-oxide). Reaction mechanisms and chemical structures of products are proposed, based on the available active sites and past literature on ozone reaction mechanisms. The experimental results are compared to theory and literature on ozone reactive sites and ozone reaction mechanisms. All in all this shows that there can be multiple ozonation products, and ozonation pathways can be complex, even if initially only one ozonation product is formed.

Enhanced database creation with in silico workflows for suspect screening of unknown tebuconazole transformation products in environmental samples by UHPLC-HRMS

The search and identification of organic contaminants in agricultural watersheds has become a crucial effort to better characterize watershed contamination by pesticides. The past decade has brought a more holistic view of watershed contamination via the deployment of powerful analytical strategies such as non-target and suspect screening analysis that can search more contaminants and their transformation products. However, suspect screening analysis remains broadly confined to known molecules, primarily due to the lack of analytical standards and suspect databases for unknowns such as pesticide transformation products. Here we developed a novel workflow by cross-comparing the results of various in silico prediction tools against literature data to create an enhanced database for suspect screening of pesticide transformation products. This workflow was applied on tebuconazole, used here as a model pesticide, and resulted in a suspect screening database counting 291 transformation products. The chromatographic retention times and tandem mass spectra were predicted for each of these compounds using 6 models based on multilinear regression and more complex machine-learning algorithms. This comprehensive approach to the investigation and identification of tebuconazole transformation products was retrospectively applied on environmental samples and found 6 transformation products identified for the first time in river water samples.

Analysis of electrochemical and liver microsomal transformation products of lasalocid by LC/HRMS

RATIONALE

Lasalocid (LAS), an ionophore, is used in cattle and poultry farming as feed additive for its antibiotic and growth-promoting properties. Literature on transformation products (TP) resulting from LAS degradation is limited. So far, only hydroxylation is found to occur as the metabolic reaction during the LAS degradation. To investigate potential TPs of LAS, we used electrochemistry (EC) and liver microsome (LM) assays to synthesize TPs, which were identified using liquid chromatography high-resolution mass spectrometry (LC/HRMS).

METHODS

Electrochemically produced TPs were analyzed online by direct coupling of the electrochemical cell to the electrospray ionization (ESI) source of a Sciex Triple-TOF high resolution mass spectrometer. Then, EC-treated LAS solution was collected and analyzed offline using LC/HRMS to confirm stable TPs and improve their annotation with a chemical structure due to informative MS/MS spectra. In a complementary approach, TPs formed by rat and human microsomal incubation were investigated using LC/HRMS. The resulting data were used to investigate LAS modification reactions and elucidate the chemical structure of obtained TPs.

RESULTS

The online measurements identified a broad variety of TPs, resulting from modification reactions like (de-)hydrogenation, hydration, methylation, oxidation as well as adduct formation with methanol. We consistently observed different ion complexations of LAS and LAS-TPs (Na⁺ ; 2Na⁺ K⁺ ; NaNH₄ ⁺ ; KNH₄ ⁺ ). Two stable methylated EC-TPs were found, structurally annotated, and assigned to a likely modification reaction. Using LM incubation, seven TPs were formed, mostly by oxidation/hydroxylation. After the identification of LM-TPs as Na⁺ -complexes, we identified LM-TPs as K⁺ -complexes.

CONCLUSION

We identified and characterized TPs of LAS using EC- and LM-based methods. Moreover, we found different ion complexes of LAS-based TPs. This knowledge, especially the different ion complexes, may help elucidate the metabolic and environmental degradation pathways of LAS.