Assessing accuracy, precision and selectivity using quality controls for non-targeted analysis

Investigating the chemical space coverage of multiple chromatographic and ionization methods using non-targeted analysis on surface and drinking water collected using passive sampling

Multiple non-targeted analysis tools were used to look for a broad range of possible chemical contaminants present in surface and drinking water using liquid chromatography separation and high-resolution mass spectrometry detection, including both quadrupole time of flight (Q-ToF) and Orbitrap instruments. Two chromatographic techniques were evaluated on an LC-Q-ToF with electrospray ionization in both positive and negative modes: (1) the traditionally used reverse phase C18 and (2) the hydrophilic interaction liquid chromatography (HILIC) aimed to capture more polar contaminants that may be present in water. Multiple ionization modes were evaluated with an LC-Orbitrap, including electrospray (ESI) and atmospheric pressure chemical ionization (APCI), also in both positive and negative modes. A suspect screening library of over 1300 possible environmental contaminants, including pesticides, pharmaceuticals, personal care products, illicit drugs/drugs of abuse, and various anthropogenic markers was made with experimentally collected data with the LC-Q-ToF with both column types, with 227 chemicals being retained by the HILIC column. The non-targeted methods using multiple chromatographic and ionization modes were applied to environmental water samples collected with polar organic chemical integrative samplers (POCIS), including surface water upstream and downstream from wastewater effluent discharge, and the downstream drinking water intake and treated drinking water for three distinct sampling events. For the LC-Q-ToF, 442 chemical features were detected on the C18 column and 91 with the HILIC column in the POCIS extracts, while 556 features were found on the Orbitrap workflow by ESI and 131 features detected by APCI. Over 100 chemicals were tentatively identified by suspect screening and database searching. The comprehensive and systematic evaluation of these methods serve as a step in characterizing the chemical space covered when utilizing different chromatography and ionization methods, or different instrument workflows on complex environmental mixtures.

Development of a robust non-targeted analysis approach for fast identification of endocrine disruptors and their metabolites in human urine for exposure assessment

Endocrine disrupting chemicals are of concern because of possible human health effects, thus they are frequently included in biomonitoring studies. Current analytical methods are focused on known chemicals and are incapable of identifying or quantifying other unknown chemicals and their metabolites. Non-targeted analysis (NTA) methods are advantageous since they allow for broad chemical screening, which provides a more comprehensive characterization of human chemical exposure, and can allow elucidation of metabolic pathways for unknown chemicals. There are still many challenges associated with NTA, which can impact the results obtained. The chemical space, i.e., the group of known and possible compounds within the scope of the method, must clearly be defined based on the sample preparation, as this is critical in identifying chemicals with confidence. Data acquisition modes and mobile phase additives used with liquid chromatography coupled to high-resolution mass-spectrometry can affect the chemicals ionized and structural identification based on the spectral quality. In this study, a sample preparation method was developed using a novel clean-up approach with CarbonS cartridges, for endocrine-disrupting chemicals in urine, including new bisphenol A analogues and benzophenone-based UV filters, like methyl bis (4-hydroxyphenyl acetate). The study showed that data dependent acquisition (DDA) had a lower identification rate (40%) at low spiking levels, i.e., 1 ng/mL, compared to data independent acquisition (DIA) (57%), when Compound Discoverer was used. In DDA, more compounds were identified using Compound Discoverer, with an identification rate of 95% when ammonium acetate was compared to acetic acid (82%) as a mobile phase additive. TraceFinder software had an identification rate of 53% at 1 ng/mL spiking level using the DDA data, compared to 40% using the DIA data. Using the developed method, 2,4 bisphenol F was identified for the first time in urine samples. The results show how NTA can provide human exposure information for risk assessment and regulatory action but standardized reporting of procedures is needed to ensure study results are reproducible and accurate. His Majesty the King in Right of Canada, as represented by the Minister of Health, 2024.

Innovative non-targeted screening approach using High-resolution mass spectrometry for the screening of organic chemicals and identification of specific tracers of soil and dust exposure in children

Environmental contamination through direct contact, ingestion and inhalation are common routes of children's exposure to chemicals, in which through indoor and outdoor activities associated with common hand-to-mouth, touching objects, and behavioral tendencies, children can be susceptible and vulnerable to organic contaminants in the environment. The objectives of this study were the screening and identification of a wide range of organic contaminants in indoor dust, soil, food, drinking water, and urine matrices (N = 439), prioritizing chemicals to assess children's environmental exposure, and selection of unique tracers of soil and dust ingestion in young children by non-targeted analysis (NTA) using Q-Exactive Orbitrap followed data processing by the Compound Discoverer (v3.3, SP2). Chemical features were first prioritized based on their predominant abundance (peak area>500,000), detection frequency (in >50% of the samples), available information on their uses and potential toxicological effects. Specific tracers of soil and dust exposure in children were selected in this study including Tripropyl citrate and 4-Dodecylbenzenesulfonic acid. The criteria for selection of the tracers were based on their higher abundance, detection frequency, unique functional uses, measurable amounts in urine (suitable biomarker), and with information on gastrointestinal absorption, metabolism, and excretion, and were further confirmed by authentic standards. We are proposing for the first time suitable unique tracers for dust ingestion by children.

Profiling emerging micropollutants in urban stormwater runoff using suspect and non-target screening via high-resolution mass spectrometry

Urban surface runoff contains chemicals that can negatively affect water quality. Urban runoff studies have determined the transport dynamics of many legacy pollutants. However, less attention has been paid to determining the first-flush effects (FFE) of emerging micropollutants using suspect and non-target screening (SNTS). Therefore, this study employed suspect and non-target analyses using liquid chromatography-high resolution mass spectrometry to detect emerging pollutants in urban receiving waters during stormwater events. Time-interval sampling was used to determine occurrence trends during stormwater events. Suspect screening tentatively identified 65 substances, then, their occurrence trend was grouped using correlation analysis. Non-target peaks were prioritized through hierarchical cluster analysis, focusing on the first flush-concentrated peaks. This approach revealed 38 substances using in silico identification. Simultaneously, substances identified through homologous series observation were evaluated for their observed trends in individual events using network analysis. The results of SNTS were normalized through internal standards to assess the FFE, and the most of tentatively identified substances showed observed FFE. Our findings suggested that diverse pollutants that could not be covered by target screening alone entered urban water through stormwater runoff during the first flush. This study showcases the applicability of the SNTS in evaluating the FFE of urban pollutants, offering insights for first-flush stormwater monitoring and management.

Exploring applications of non-targeted analysis in the characterization of the prenatal exposome

Capturing the breadth of chemical exposures in utero is critical in understanding their long-term health effects for mother and child. We explored methodological adaptations in a Non-Targeted Analysis (NTA) pipeline and evaluated the effects on chemical annotation and discovery for maternal and infant exposure. We focus on lesser-known/underreported chemicals in maternal and umbilical cord serum analyzed with liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). The samples were collected from a demographically diverse cohort of 296 maternal-cord pairs (n = 592) recruited in San Francisco Bay area. We developed and evaluated two data processing pipelines, primarily differing by detection frequency cut-off, to extract chemical features from non-targeted analysis (NTA). We annotated the detected chemical features by matching with EPA CompTox Chemicals Dashboard (n = 860,000 chemicals) and Human Metabolome Database (n = 3140 chemicals) and applied a Kendrick Mass Defect filter to detect homologous series. We collected fragmentation spectra (MS/MS) on a subset of serum samples and matched to an experimental MS/MS database within the MS-Dial website and other experimental MS/MS spectra collected from standards in our lab. We annotated ~72 % of the features (total features = 32,197, levels 1-4). We confirmed 22 compounds with analytical standards, tentatively identified 88 compounds with MS/MS spectra, and annotated 4862 exogenous chemicals with an in-house developed annotation algorithm. We detected 36 chemicals that appear to not have been previously reported in human blood and 9 chemicals that were reported in less than five studies. Our findings underline the importance of NTA in the discovery of lesser-known/unreported chemicals important to characterize human exposures.

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.

Application of Nontarget High-Resolution Mass Spectrometry Fingerprints for Qualitative and Quantitative Source Apportionment: A Real Case Study

High-resolution mass spectrometry (HRMS) provides extensive chemical data, facilitating the differentiation and quantification of contaminants of emerging concerns (CECs) in aquatic environments. This study utilizes liquid chromatography-HRMS for source apportionment in Chebei Stream, an urban water stream in Guangzhou, South China. Initially, 254 features were identified as potential CECs by the nontarget screening (NTS) method. We then established 1689, 1317, and 15,759 source-specific HRMS fingerprints for three distinct sources, the mainstream (C3), the tributary (T2), and the rain runoff (R1), qualitatively assessing the contribution from each source downstream. Subsequently, 32, 55, and 3142 quantitative fingerprints were isolated for sites C3, T2, and R1, respectively, employing dilution curve screening for source attribution. The final contribution estimates downstream from sites C3, T2, and R1 span 32-96, 12-23, and 8-23%, respectively. Cumulative contributions from these sources accurately mirrored actual conditions, fluctuating between 103 and 114% across C6 to C8 sites. Yet, with further tributary integration, the overall source contribution dipped to 52%. The findings from this research present a pioneering instance of applying HRMS fingerprints for qualitative and quantitative source tracking in real-world scenarios, which empowers the development of more effective strategies for environmental protection.

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.

An integrated non-targeted and targeted analysis approach for identification of semi-volatile organic compounds in indoor dust

Household dust contains a wide variety of semi-volatile organic compounds (SVOCs) that may pose health risks. We developed a method integrating non-targeted analysis (NTA) and targeted analysis (TA) to identify SVOCs in indoor dust. Based on a combined use of gas and liquid chromatography with high-resolution mass spectrometry, an automated, time-efficient NTA workflow was developed, and high accuracy was observed. A total of 128 compounds were identified at confidence level 1 or 2 in NIST standard reference material dust (SRM 2585). Among them, 113 compounds had not been reported previously, and this suggested the value of NTA in characterizing contaminants in dust. Additionally, TA was done to avoid the loss of trace compounds. By integrating data obtained from the NTA and TA approaches, SVOCs in SRM 2585 were prioritized based on exposure and chemical toxicity. Six of the top 20 compounds have never been reported in SRM 2585, including melamine, dinonyl phthalate, oxybenzone, diheptyl phthalate, drometrizole, and 2-phenylphenol. Additionally, significant influences of analytical instruments and sample preparation on NTA results were observed. Overall, the developed method provided a powerful tool for identifying SVOCs in indoor dust, which is necessary to obtain a more complete understanding of chemical exposures and risks in indoor environments.

Identification of disinfection by-products (DBP) in thermal water swimming pools applying non-target screening by LC-/GC-HRMS

The discovery of new disinfection by-products (DBPs) is still a rarely investigated research area in past studies. In particular, compared to freshwater pools, therapeutic pools with their unique chemical composition have rarely been investigated for novel DBPs. Here we have developed a semi-automated workflow that combines data from target and non-target screening, calculated and measured toxicities into a heat map using hierarchical clustering to assess the pool's overall potential chemical risk. In addition, we used complementary analytical techniques such as positive and negative chemical ionization to demonstrate how novel DBPs can be better identified in future studies. We identified two representatives of the haloketones (pentachloroacetone, and pentabromoacetone) and tribromo furoic acid detected for the first time in swimming pools. Non-target screening combined with target analysis and toxicity assessment may help to define risk-based monitoring strategies in the future, as required by regulatory frameworks for swimming pool operations worldwide.

Evaluating non-targeted analysis methods for chemical characterization of organic contaminants in different matrices to estimate children's exposure

BACKGROUND

Children are vulnerable to environmental exposure of contaminants due to their small size, lack of judgement skills, as well as their proximity to dust, soil, and other environmental sources. A better understanding about the types of contaminants that children are exposed to or how their bodies retain or process these compounds is needed.

OBJECTIVE

In this study, we have implemented and optimized a methodology based on non-targeted analysis (NTA) to characterize chemicals in dust, soil, urine, and in the diet (food and drinking water) of infant populations.

METHODS

To evaluate potential toxicological concerns associated with chemical exposure, families with children between 6 months and 6 years of age from underrepresented groups were recruited in the greater Miami area. Samples of soil, indoor dust, food, water, and urine were provided by the caregivers, prepared by different techniques (involving online SPE, ASE, USE, QuEChERs), and analyzed by liquid chromatography-high resolution mass spectrometry (LC-HRMS). Data post-processing was performed using the small molecule structure identification software, Compound Discoverer (CD) 3.3, and identified features were plotted using Kendrick mass defect plot and Van Krevelen diagrams to show unique patterns in different samples and regions of anthropogenic compound classifications.

RESULTS

The performance of the NTA workflow was evaluated using quality control standards in terms of accuracy, precision, selectivity, and sensitivity, with an average of 98.2%, 20.3%, 98.4% and 71.1%, respectively. Sample preparation was successfully optimized for soil, dust, water, food, and urine. A total of 30, 78, 103, 20 and 265 annotated features were frequently identified (detection frequency >80%) in the food, dust, soil, water, and urine samples, respectively. Common features detected in each matrix were prioritized and classified, providing insight on children's exposure to organic contaminants of concern and their potential toxicities.

IMPACT STATEMENT

Current methods to assess the ingestion of chemicals by children have limitations and are generally restricted by specific classes of targeted organic contaminants of interest. This study offers an innovative approach using non-targeted analysis for the comprehensive screening of organic contaminants that children are exposed to through dust, soil, and diet (drinking water and food).

Enrichment and analysis methods for trace dissolved organic carbon in reverse osmosis effluent: A review

Reverse osmosis (RO) is an essential unit for producing high-quality ultrapure water. The increasingly severe water shortage and water quality deterioration result in reclaimed water as an alternative source for ultrapure water production. However, when using reclaimed water as water sources, the dissolved organic carbon (DOC) in RO permeate exhibits higher concentration and more sophisticated components than when using clean water sources, thus affecting the effluent quality of ultrapure water and the effectiveness of subsequent treatment processes. To optimize the treatment processes, it is crucial to analyze the components of DOC. This review summarizes the enrichment and analysis methods of trace organic matter, and provides recommendations for the analysis and characterization of DOC in RO permeate. The study summarizes the operating conditions and enrichment properties of different enrichment methods, including solid-phase extraction, liquid-liquid extraction, purge-and-trap, lyophilization and rotary evaporation for low-concentration organic compounds, compares the applicability and limitations of different enrichment methods, and proposes the principles for the selection of enrichment methods. In this review, we discuss the application of mass spectrometry (including Fourier transform ion cyclotron resonance mass spectrometry) in the analysis of DOC components, and focus on data processing as the key procedure in analysis of DOC in RO permeate. Despite the advantages of mass spectrometry, an applicable workflow and open-source database are required to improve the reliability of the analysis. The treatability properties of DOC are suggested to be determined by analyzing the component characteristics or in combination with common removal techniques. This study provides theoretical support for a comprehensive analysis of DOC in RO permeates to improve the removal effect.

Comprehensive assessment of chemical residues in surface and wastewater using passive sampling, chemical, biological, and fish behavioral assays

Effluents from ten full-scale municipal wastewater treatment plants (WWTPs) that discharge into the Hudson River, surface waters, and wild-caught fish samples were analyzed using liquid chromatography with tandem mass spectrometry (LC/MS/MS) to examine the influence of wastewater discharge on the concentrations of contaminants of emerging concern (CECs) and their ecological impacts on fish. Analysis was based on targeted detection of 41 pharmaceuticals, and non-targeted analysis (suspect screening) of CECs. Biological effects of treated WWTP effluents were assessed using a larval zebrafish (Danio rerio) swimming behavior assay. Concentrations of residues in surface waters were determined in grab samples and polar organic chemical integrative samplers (POCIS). In addition, vitellogenin peptides, used as biomarkers of endocrine disruption, were quantified using LC/MS/MS in the wild-caught fish plasma samples. Overall, 94 chemical residues were identified, including 63 pharmaceuticals, 10 industrial chemicals, and 21 pesticides. Eight targeted pharmaceuticals were detected in 100% of effluent samples with median detections of: bupropion (194 ng/L), carbamazepine (91 ng/L), ciprofloxacin (190 ng/L), citalopram (172 ng/L), desvenlafaxine (667 ng/L), iopamidol (3790 ng/L), primidone (86 ng/L), and venlafaxine (231 ng/L). Over 30 chemical residues were detected in wild-caught fish tissues. Notably, zebrafish larvae exposed to chemical extracts of effluents from 9 of 10 WWTPs, in at least one season, were significantly hyperactive. Vitellogenin expression in male or immature fish occurred 2.8 times more frequently in fish collected from the Hudson River as compared to a reference site receiving no direct effluent input. Due to the low concentrations of pharmaceuticals detected in effluents, it is likely that chemicals other than pharmaceuticals measured are responsible for the behavioral changes observed. The combined use of POCIS and non-target analysis demonstrated significant increase in the chemical coverage for CEC detection, providing a better insight on the impacts of WWTP effluents and agricultural practices on surface water quality.

Hurricane Damage Detection From Satellite Imagery Using Convolutional Neural Networks

Hurricanes are one of the most disastrous natural phenomena occurring on Earth that cause loss of human lives and immense damage to property as well. For assessment of this damage, windshield survey is commonly used, which is an error-prone and time-consuming method. For solving this problem, computer vision comes into the picture. In this paper, a convolutional neural network-based architecture has been proposed to classify the post-hurricane satellite imagery into damaged and undamaged building classes accurately. The model consists of five convolutional and five pooling layers followed by a flattening layer and two dense layers. For this, a dataset of Hurricane Harvey has been considered having 23000 satellite images each of size 128 X 128 pixels. With the proposed model, the author has achieved an accuracy of 92.91%, F1-score of 93%, sensitivity of 93.34%, specificity of 92.47%, and precision of 92.65% at a learning rate of 0.0001 and 30 epochs. Also, low false positive rate of 7.53% and false negative rate of 6.66% were obtained.

Non-targeted analysis with liquid chromatography - high resolution mass spectrometry for the identification of food packaging migrants

Potential contamination of food with chemicals migrating from food packaging is an important, yet under-investigated area of food safety. In this study, we examined chemicals migrating from common paper-based food packaging: pizza boxes and pizza box liners, butcher paper and liquid egg containers. Migration tests were conducted with a food simulant for 10 days, and migrated chemicals were identified with liquid chromatography (LC) - high resolution mass spectrometry (HRMS) with mass error < 3 ppm. HRMS identification was based on spectra and/or structure matching against commercial databases (MzCloud, ChemSpider, and Extractable and Leachable high resolution accurate mass (HRAM) database). Following HRMS identification, orthogonal LC retention information was utilized to further refine the data and reduce false positive findings. A model for calculating retention times (t_R) based on octanol-water partition coefficient (log K_ow) values was evaluated and applied for HRMS data refining. Using this approach, 153 migrated chemicals were identified, of which five were further confirmed with reference analytical standards. Additionally, amounts of bisphenol A and bisphenol S, the chemicals of toxicological concerns, were measured at the levels below the established regulatory limits for migration, indicating no/low risk to consumer's health. This study demonstrated the utility of LC-HRMS for confident identification of food packaging migrants.

Differential Organic Contaminant Ionization Source Detection and Identification in Environmental Waters by Nontargeted Analysis

The development of nontargeted analysis (NTA) methods to assess environmental contaminants of emerging concern, which are not commonly monitored, is paramount, especially when no previous knowledge on the identity of the pollution source is available. We compared complementary ionization techniques, namely electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI), in the detection and identification of organic contaminants in tap and surface waters from South Florida. Furthermore, the performance of a simple rationalized NTA method was assessed by analyzing 10 complex mixtures as part of the US Environmental Protection Agency's Non-targeted Analysis Collaborative Trial interlaboratory study, where limitations of the NTA approach have been identified (e.g., number of employed databases, false positives). Different water bodies displayed unique chemical features that can be used as chemical fingerprints for source tracking and discrimination. The APCI technique detected at least threefold as many chemical features as ESI in environmental water samples, corroborating the fact that APCI is more energetic and can ionize certain classes of compounds that are traditionally difficult to ionize by liquid chromatography-mass spectrometry. Kendrick mass defect plots and Van Krevelen diagrams were applied to elucidate unique patterns and theoretical chemical space regions of anthropogenic organic compounds belonging to homologous series or similar classes covered by ESI and APCI. Overall, APCI and ESI were established as complementary, expanding the detected NTA chemical space which would otherwise be underestimated by a single ionization source operated in a single polarity setting. Environ Toxicol Chem 2022;41:1154-1164. © 2021 SETAC.

Detecting Water Constituents Unique to Septic Tanks as a Wastewater Source in the Environment by Nontarget Analysis: South Florida's Deering Estate Rehydration Project Case Study

The present study has generated a workflow based on nontarget analysis (NTA) with Compound Discoverer Ver 3.1 to characterize a set of source-discriminating compounds identified in water samples from locations in South Florida (USA), particularly those describing a freshwater environment (Everglades based), urban impacted areas (septic tank driven), and coastal (Biscayne Bay) endmembers in and around the Charles Deering Estate property in the Village of Palmetto Bay. Waters from an interconnected managed canal system were assessed to evaluate the influence of localized emissions. Septic tank effluents influence the water in many Southeast Florida environments due to their diminished onsite treatment capacity based on the limestone-dominated geology and canal systems providing a relatively unobstructed connection pathway. Through a combination of high-resolution mass spectrometry and statistical analyses, a set of tracers and indicators was determined (azelaic acid, decanophenone, galaxolidone, methyl violet, monoolein, metoprolol, and 1-stearoylglycerol). Tentatively identified compounds were generally assigned to various categories such as dyes, personal care products, and pharmaceuticals. The NTA Compound Discoverer Ver 3.1 compound data (presented as principal component analysis and Kendrick mass defect plots) showed apparent differences between wastewater-influenced sites and non-wastewater-influenced sites along with the ranked "Top10" compounds found at each location. Waters from different locations were also compared using the presence of sucralose to further inform the NTA. The most septic-influenced site contained 3594 ± 94 ng/L of sucralose with concentrations declining steadily and reaching the lowest concentrations in Biscayne Bay of 122 ± 94 ng/L. The sucralose concentrations provided further evidence of septic influence on this system. Sucralose was determined to be a conservative tracer between the freshwater and coastal sources and complementary to other probable unique tracers of septic tank effluent identified by the NTA. Environ Toxicol Chem 2022;41:1165-1178. © 2022 SETAC.

Screening organic contaminants in soil by two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry: A non-target analysis strategy and contaminated area case study

Thousands of organic substances that are used in industrial applications ultimately enter the soil and may negatively affect human health. Limited numbers of target pollutants are usually monitored in environmental media because of analytical limitations. In this study, a non-target screening method for quickly analyzing multiple soil samples from a contaminated area (a chemical industry park) by two-dimensional gas chromatography high-resolution time-of-flight mass spectrometry was developed. The types of compounds present in the soil samples were preliminarily analyzed through data simplification and visual assessment. A total of 81 organic compounds with detection frequencies ≥40% in the samples from the chemical industry park were selected for identification, including 38 PAHs, 26 oxygenated organic compounds, eight N-containing compounds, and nine other compounds. Potential sources of the organic compounds in the industrial park were investigated. Some pharmaceutical and organic synthetic intermediates in the soil were affected by nearby chemical plants. After assessing the relative abundances and detection frequencies, 36 pollutants that may pose potential risks to the environment were preliminarily identified. The results of the study were helpful for assessing environmental risks around Yangkou industrial park and they will be helpful when assessing risks in other contaminated areas.

Chemical Characterization and Non-targeted Analysis of Medical Device Extracts: A Review of Current Approaches, Gaps, and Emerging Practices

The developers of medical devices evaluate the biocompatibility of their device prior to FDA's review and subsequent introduction to the market. Chemical characterization, described in ISO 10993-18:2020, can generate information for toxicological risk assessment and is an alternative approach for addressing some biocompatibility end points (e.g., systemic toxicity, genotoxicity, carcinogenicity, reproductive/developmental toxicity) that can reduce the time and cost of testing and the need for animal testing. Additionally, chemical characterization can be used to determine whether modifications to the materials and manufacturing processes alter the chemistry of a patient-contacting device to an extent that could impact device safety. Extractables testing is one approach to chemical characterization that employs combinations of non-targeted analysis, non-targeted screening, and/or targeted analysis to establish the identities and quantities of the various chemical constituents that can be released from a device. Due to the difficulty in obtaining a priori information on all the constituents in finished devices, information generation strategies in the form of analytical chemistry testing are often used. Identified and quantified extractables are then assessed using toxicological risk assessment approaches to determine if reported quantities are sufficiently low to overcome the need for further chemical analysis, biological evaluation of select end points, or risk control. For extractables studies to be useful as a screening tool, comprehensive and reliable non-targeted methods are needed. Although non-targeted methods have been adopted by many laboratories, they are laboratory-specific and require expensive analytical instruments and advanced technical expertise to perform. In this Perspective, we describe the elements of extractables studies and provide an overview of the current practices, identified gaps, and emerging practices that may be adopted on a wider scale in the future. This Perspective is outlined according to the steps of an extractables study: information gathering, extraction, extract sample processing, system selection, qualification, quantification, and identification.

Assessing Reliability of Non-targeted High-Resolution Mass Spectrometry Fingerprints for Quantitative Source Apportionment in Complex Matrices

Effective management of contaminated sites requires differentiating and deconvoluting contaminant source impacts in complex environmental systems. The existing source apportionment approaches that use targeted analyses of preselected indicator chemicals are limited whenever target analytes are below the detection limits or derived from multiple sources. However, non-targeted analyses that leverage high-resolution mass spectrometry (HRMS) yield rich datasets that deeply characterize sample-specific chemical compositions, providing additional potential end-members for source differentiation and apportionment. Previous work demonstrated that HRMS fingerprints can define sample uniqueness and support accurate, quantitative source concentration estimates. Here, using two aqueous film-forming foams as representative complex sources, we assessed the qualitative fidelity and quantitative accuracy of HRMS source fingerprints in increasingly complex background matrices. Across all matrices, HRMS-derived source concentration estimates were 0.81 ± 0.11-fold and 0.64 ± 0.24-fold of actual in samples impacted solely by analytical matrix effects (MEs) or by sample processing recovery and analytical MEs, respectively. Isotopic internal standards were not easily paired to individual unidentified non-target features, but bulk internal standard-based abundance corrections improved apportionment accuracy in higher matrix samples (to 0.90 ± 0.12-fold of actual) and/or informed concentration estimate relative errors. HRMS fingerprint mining could identify, based on the dilution behavior, effective individual chemical end-members across 16 homologous series. Although method development is needed, the results further demonstrate the potential applications of non-targeted HRMS data for source apportionment and other quantitative outcomes.

Ecological and spatial variations of legacy and emerging contaminants in white-tailed sea eagles from Germany: Implications for prioritisation and future risk management

The increasing use of chemicals in the European Union (EU) has resulted in environmental emissions and wildlife exposures. For approving a chemical within the EU, producers need to conduct an environmental risk assessment, which typically relies on data generated under laboratory conditions without considering the ecological and landscape context. To address this gap and add information on emerging contaminants and chemical mixtures, we analysed 30 livers of white-tailed sea eagles (Haliaeetus albicilla) from northern Germany with high resolution-mass spectrometry coupled to liquid and gas chromatography for the identification of >2400 contaminants. We then modelled the influence of trophic position (δ¹⁵N), habitat (δ¹³C) and landscape on chemical residues and screened for persistent, bioaccumulative and toxic (PBT) properties using an in silico model to unravel mismatches between predicted PBT properties and observed exposures. Despite having generally low PBT scores, most detected contaminants were medicinal products with oxfendazole and salicylamide being most frequent. Chemicals of the Stockholm Convention such as 4,4'-DDE and PCBs were present in all samples below toxicity thresholds. Among PFAS, especially PFOS showed elevated concentrations compared to other studies. In contrast, PFCA levels were low and increased with δ¹⁵N, which indicated an increase with preying on piscivorous species. Among plant protection products, spiroxamine and simazine were frequently detected with increasing concentrations in agricultural landscapes. The in silico model has proven to be reliable for predicting PBT properties for most chemicals. However, chemical exposures in apex predators are complex and do not solely rely on intrinsic chemical properties but also on other factors such as ecology and landscape. We therefore recommend that ecological contexts, mixture toxicities, and chemical monitoring data should be more frequently considered in regulatory risk assessments, e.g. in a weight of evidence approach, to trigger risk management measures before adverse effects in individuals or populations start to manifest.

An Introduction to the Benchmarking and Publications for Non-Targeted Analysis Working Group

Non-targeted analysis (NTA) encompasses a rapidly evolving set of mass spectrometry techniques aimed at characterizing the chemical composition of complex samples, identifying unknown compounds, and/or classifying samples, without prior knowledge regarding the chemical content of the samples. Recent advances in NTA are the result of improved and more accessible instrumentation for data generation and analysis tools for data evaluation and interpretation. As researchers continue to develop NTA approaches in various scientific fields, there is a growing need to identify, disseminate, and adopt community-wide method reporting guidelines. In 2018, NTA researchers formed the Benchmarking and Publications for Non-Targeted Analysis Working Group (BP4NTA) to address this need. Consisting of participants from around the world and representing fields ranging from environmental science and food chemistry to 'omics and toxicology, BP4NTA provides resources addressing a variety of challenges associated with NTA. Thus far, BP4NTA group members have aimed to establish a consensus on NTA-related terms and concepts and to create consistency in reporting practices by providing resources on a public Web site, including consensus definitions, reference content, and lists of available tools. Moving forward, BP4NTA will provide a setting for NTA researchers to continue discussing emerging challenges and contribute to additional harmonization efforts.

Change in the chemical content of untreated wastewater of Athens, Greece under COVID-19 pandemic

COVID-19 pandemic spread rapidly worldwide with unanticipated effects on mental health, lifestyle, stability of economies and societies. Although many research groups have already reported SARS-CoV-2 surveillance in untreated wastewater, only few studies evaluated the implications of the pandemic on the use of chemicals by influent wastewater analysis. Wide-scope target and suspect screening were used to monitor the effects of the pandemic on the Greek population through wastewater-based epidemiology. Composite 24 h influent wastewater samples were collected from the wastewater treatment plant of Athens during the first lockdown and analyzed by liquid chromatography mass spectrometry. A wide range of compounds was investigated (11,286), including antipsychotic drugs, illicit drugs, tobacco compounds, food additives, pesticides, biocides, surfactants and industrial chemicals. Mass loads of chemical markers were estimated and compared with the data obtained under non-COVID-19 conditions (campaign 2019). The findings revealed increases in surfactants (+196%), biocides (+152%), cationic quaternary ammonium surfactants (used as surfactants and biocides) (+331%), whereas the most important decreases were estimated for tobacco (-33%) and industrial chemicals (-52%). The introduction of social-restriction measures by the government affected all aspects of life.

Transcriptome and Metabolome Analysis Revealed the Freezing Resistance Mechanism in 60-Year-Old Overwintering Camellia sinensis

Simple Summary

The freezing stress during overwintering brings great challenges to the normal growth of Camellia sinensis. The current research on C. sinensis mainly focuses on cold resistance, but less on freezing resistance. In the present study, the transcriptome and metabolome of C. sinensis under freezing stress were studied. Results showed that Pyr/PYL-PP2C-SnRK2 played a critical role in the signal transduction of freezing stress. Three metabolic pathways including phenylpropanoid biosynthesis, flavone and flavonol biosynthesis, and flavonoid biosynthesis contributed to the freezing resistance of C. sinensis. This study provides substantial insights for the breeding of C. sinensis.

Abstract

Freezing stress in winter is the biggest obstacle to the survival of C. sinensis in mid-latitude and high-latitude areas, which has a great impact on the yield, quality, and even life of C. sinensis every year. In this study, transcriptome and metabolome were used to clarify the freezing resistance mechanism of 60-year-old natural overwintering C. sinensis under freezing stress. Next, 3880 DEGs and 353 DAMs were obtained. The enrichment analysis showed that pathways of MAPK and ABA played a key role in the signal transduction of freezing stress, and Pyr/PYL-PP2C-SnRK2 in the ABA pathway promoted stomatal closure. Then, the water holding capacity and the freezing resistance of C. sinensis were improved. The pathway analysis showed that DEGs and DAMs were significantly enriched and up-regulated in the three-related pathways of phenylpropanoid biosynthesis, flavone and flavonol biosynthesis, and flavonoid biosynthesis. In addition, the carbohydrate and fatty acid synthesis pathways also had a significant enrichment, and the synthesis of these substances facilitated the freezing resistance. These results are of great significance to elucidate the freezing resistance mechanism and the freezing resistance breeding of C. sinensis.

Simultaneous Determination of the Five Constituents in Maiwei Dihuang Pills by the HPLC-DAD Method

OBJECTIVE

The purpose of study is to establish an HPLC-DAD method for determination of the five constituents (deoxyschizandrin, γ-schizandrin, loganin, paeoniflorin, and paeonol) in Maiwei Dihuang Pills.

METHODS

An Agilent ZORBAX SB-C18 chromatographic column was carried out to determine the five constituents of 50% methanol extract of Maiwei Dihuang Pills.

RESULTS

It was found the chromatographic peak resolution of each component in the study sample solution was 1.5 higher than that of other peaks and no peaks appeared in the blank control solution during the same time, suggesting specificity of HPLC-DAD was well established. The linearity test indicated that deoxyschizandrin, γ-schizandrin, loganin, paeoniflorin, and paeonol were 11.6-72.3 μg/mL, 6.4-45.2 μg/mL, 35.2-237.6 μg/mL, 18.1-114.2 μg/mL, and 32.2-215.3 μg/mL, respectively, suggesting each component has a good linear relationship within its own range. Additionally, the precision of HPLC-DAD was confirmed by a precision test; the stability of the study sample solution was confirmed by a stability test; and good reproducibility of HPLC-DAD was proved by a reproducible test. The recovery rate test showed that relative standard deviation (RSD) of recovery rate in deoxyschizandrin, γ-schizandrin, loganin, paeoniflorin, and paeonol was 100.26% (1.80%), 101.39% (1.74%), 101.19% (1.76%), 102.50% (1.65%), and 102.30% (1.58%), respectively.

CONCLUSIONS

HPLC-DAD used to determine the five constituents in Maiwei Dihuang Pills, and it was easier and faster to operate, showing good condition in repeatability, precision, stability, and recovery, which is a great option for quality control.

Suspect screening of pharmaceuticals in fish livers based on QuEChERS extraction coupled with high resolution mass spectrometry

The presence of pharmaceuticals and personal care products (PPCPs) in aquatic environments is of increasing concern due to the presence of residues in fish and aquatic organisms, and emerging antibiotic resistance. Wastewater release is an important contributor to the presence of these compounds in aquatic ecosystems, where they may accumulate in food webs. The traditional environmental surveillance approach relies on the targeted analysis of specific compounds, but more suspect screening methods have been developed recently to allow for the identification of a variety of contaminants. In this study, a method based on QuEChERS extraction - using acetonitrile/water mixture as solvent and PSA/C₁₈ for sample clean-up - was applied to identify pharmaceuticals and their metabolites in fish livers. Both target and suspect screening workflows were used and fish were sampled upstream and downstream of wastewater treatment plants from the Scioto River, Ohio (USA). The method performed well in terms of extraction of some target PPCPs, with recoveries generally above 90%, good repeatability (<20%), and linearity. Based on target analysis, lincomycin and sulfamethoxazole were two antibiotics identified in fish livers at average concentrations of 30.3 and 25.6 ng g^-1 fresh weight, respectively. Using suspect screening, another antibiotic, azithromycin and an antidepressant metabolite, erythrohydrobupropion were identified (average concentrations: 27.8 and 13.8 ng g^-1, respectively). The latter, reported, to the best of our knowledge, for the first time in fish livers, was also found at higher concentrations in fish livers sampled downstream vs. upstream. The higher frequency of detection for azithromycin in benthic feeding fish species (63%) as well as clusters identified between different foraging groups suggest that foraging behavior may be an important mechanism in the bioaccumulation of PPCPs. This study shows how suspect screening is effective in identifying new contaminants in fish livers, notably using differential analysis among different spatially distributed samples.

Comment on "Optimization of suspect and non-target analytical methods using GC/TOF for prioritization of emerging contaminants in the Arctic environment"

Lee et al. (2019) recently proposed that volatile methylsiloxanes (VMS) be considered as emerging contaminants in the Arctic environment based on the results of suspect and non-target screening of environmental samples collected from Ny-Ålesund, Svalbard. In any analytical program, it is of critical importance to be able to discern if the identification of analytes is due to true presence in the sampled environmental media or if contamination occurred during sample handling and analysis, leading to false positive detection. This is particularly important for VMS due to their ubiquity in consumer products, sample containers, and analytical instrumentation, thus requiring robust quality control (QC) procedures to support the validity of results. Although Lee et al. (2019) concluded that VMS in the environmental samples originated from potential long-range transport and deposition, it is most likely that local point sources account for their presence. Additionally, there is low confidence in the validity of the reported detection of VMS in the sampled environmental media as this study does not include any of the necessary QC to determine whether the VMS detected would be due to contamination or indicative of presence in the environment.

Development of a Data Analysis Tool to Determine the Measurement Variability of Consensus Mass Spectra

The success of nontargeted analysis often depends on libraries containing reference mass spectra of known chemical compounds; the mass spectra of unknown compounds are compared to these reference mass spectra, leading to a probable compound identity. Typical calculations include the mean measured values for each ion m/z and intensity with no estimation of the variability of the measurement. This study presents a novel tool for the calculation of the variability of a measured mass spectrum, including the various data parameters that can impact the measured variability. Using perfluorooctanoic acid (PFOA) as the model compound, the variability of measured data-dependent fragmentation mass spectra (ddMS2) was calculated within replicate measurements of a simple solution of PFOA and a complex mixture (house dust extract) containing PFOA. The variability of the measured ddMS2 for PFOA in the solution and house dust extract were similar, with standard deviations about the measured m/z value ranging from m/z 0.00003 to 0.00015 and the standard deviations about the measured relative intensity ranging from 0.0077 to 0.0211 relative intensity units. In addition, the selected parameters for the extraction of ddMS2 from a single analytical run varied between the sample types due to the increased presence of background ions in the house dust extract. Finally, the variability of the ddMS2 spectra for PFOA in both samples was used to calculate a more robust similarity factor, informing the confidence of the identification of unknown compounds.

Combination of high resolution mass spectrometry and a halogen extraction code to identify chlorinated disinfection byproducts formed from aromatic amino acids

Chlorination can lead to the formation of hazardous chlorinated disinfection byproducts (Cl-DBPs). We identified tyrosine (Tyr) and tryptophan (Trp) as precursors of toxic Cl-DBPs and developed a halogen extraction code to complement ultra performance liquid chromatography in tandem with high resolution mass spectrometry (UPLC-HRMS) in detecting and identifying Cl-DBPs. We detected 20 and 11 Cl-DBPs formed from chlorination of Tyr and Trp, respectively, and identified the structures of 15 Cl-DBPs. Fourteen structures were previously unreported. We also proposed the tentative formation pathways of these newly identified Cl-DBPs. Their incidence in real water sources demonstrated that these Cl-DBPs are likely to form during chlorination of reclaimed water. We computationally predicted the toxicity of these Cl-DBPs, which was relatively high, indicating that these Cl-DBPs could be hazardous and were of valid concern. Combining analytical data with the halogen extraction code can identify Cl-DBPs accurately from complex compounds. This analytical method can be used to identify Cl-DBPs of water treatment procedures in further studies.

Tracing nitrogenous byproducts during ozonation in the presence of bromide and ammonia using stable isotope labeling and high resolution mass spectrometry

Ammonia has been widely used to inhibit bromate formation during ozonation. However, our recent study found that during ozonation in the presence of bromide and ammonia, toxicity increased under certain conditions that might be attributed to the formation of nitrogenous byproducts. Herein, a typical structural moiety of natural organic matter (NOM), hydroquinone, was evaluated for its potential to form nitrogenous byproducts. During ozonation of the hydroquinone solution containing bromide and ammonia, toxicity of organic byproducts increased significantly. As organic bromine was hardly detected, organic nitrogen was responsible for the increased toxicity. An effective method combining ultra-performance liquid chromatography in tandem with high resolution mass spectrometry (UPLC-HRMS) with an isotope labeling strategy was used to trace nitrogenous byproducts. Four newly formed nitrogenous byproducts were detected, two of which were also detected in Suwannee River natural organic matter (SRNOM) solution treated under the same ozonation condition. Furthermore, the molecular structures and formation pathways of these nitrogenous byproducts were proposed. This study highlights that, despite the widespread use, adding ammonia to inhibit bromate formation during ozonation might increase the toxicity posed by nitrogenous byproducts. During ozonation in the presence of bromide and ammonia, particular attention should be paid to nitrogenous byproducts.

A Proposed Quality Control Standard Mixture and Its Uses for Evaluating Nontargeted and Suspect Screening LC/HR-MS Method Performance

Nontargeted (NTA) and suspect screening analyses (SSA) aim to detect and identify unknown compounds of interest from a given sample. The complexity and diversity of NTA and SSA methodologies necessitate the use of a comprehensive quality control standard mixture to determine if methods are fit for purpose, but to our knowledge, such a standard has not been developed that can be used by multiple disciplines, nor is one readily available. This work describes the development and analysis of a proposed nontargeted standard/quality control mixture for NTA and SSA applications using liquid chromatography/electrospray ionization-high resolution-mass spectrometry. Considerations in its development included achieving diversity of compounds with respect to elemental composition, molecular weight, retention time, and ionization in positive and/or negative ion modes, which resulted in the inclusion of 89 compounds. The utility of the standard mixture was applied on our own NTA and SSA workflows where sample preparation efficiency and potential sources of error due to instrumental and data processing methods were evaluated. Some areas in need of improvement were identified, such as hydrophilic compound detection and molecular formula generation for compounds containing fluorine. However, our overall methodology was found to be fit for purpose and we were able to establish thresholds to increase reliability and throughput of reported results.

Pharmaceuticals and other contaminants in waters and sediments from Augusta Bay (southern Italy)

The contamination by pharmaceuticals products (PPs) in the marine environment is particularly relevant where wastewater treatment of urban areas on land is lacking. However, the number of studies focused on description of sources and fate of PP molecules in the marine environment remains still limited. In this study, the occurrence of 46 PPs was investigated in the marine and coastal-marine system (waters and sediments) of Augusta Bay (central Mediterranean Sea). This area is highly affected by industrial pollution and urban discharges (without wastewater treatment) and thus represents a 'natural laboratory' for exploring dynamics of multi-mixture contaminants in the marine environment. The study area is also part of the sub-region 'Central Mediterranean Sea' of the Marine Strategy Framework Directive and therefore offers an important reference site for exploring the distribution modes of PPs in the central Mediterranean Sea. In this work, samples of seawater, sediment, untreated wastewater, and marine receiving water were analysed using mass spectrometry with a target analysis for PPs and a suspect screening analysis for the presence of other contaminants. PPs concentration ranges were: 2426-67,155 ng/L for untreated wastewaters, 550-27,889 ng/L for marine receiving waters and 12-281 ng/L for seawaters. The highest concentrations were measured for the antibiotics, anti-inflammatories, cardiovascular and antihypertensive therapeutic classes. Likewise, sediments collected from untreated wastewater sewers resulted more contaminated. Ionic, non-ionic surfactants and personal care products were the most abundant compounds found in waters and sediments by suspect screening analysis. The risk associated with PPs contamination for aquatic organisms was relatively high in samples of marine receiving waters of the bay (with a risk quotient value up to 33,599). The levels of PPs in seawater and sediment compartments were generally not hazardous (RQ < 0.01), except for estrone with a calculated RQ = 2775.