Optimization of the post-acquisition data processing for the non-targeted screening of trace leachable residues from reusable plastic bottles by high performance liquid chromatography coupled to hybrid quadrupole time of flight mass spectrometry

Identifying organic micropollutants' transformation products from the soil dissipation experiment by non-targeted high-resolution mass spectrometry approach: Can we gain more than transformation product identity?

Risk assessment of environmental hazards originating from xenobiotics extensively used worldwide (e.g., pharmaceuticals, bisphenols, or preservatives) requires a combined study of their effects, mobility, dissipation mechanisms, and subsequent transformation product identification and evaluation. We have developed an efficient accelerated solvent extraction method for a broad range of micropollutants of variable physical-chemical properties in soils to enable more accurate hazard characterisation. Micropollutant recoveries from freeze-dried soils were 60-120%, with the exception of atorvastatin, fexofenadine, and telmisartan, which had reduced recoveries (40-66%). The observed matrix effect ranged from -26% to 17% and was corrected by the matrix matching standard for quantitative analysis. The method allows sensitive and reliable determination of a wide range of analytes in soil samples and, consequently, qualitative analysis of transformation products (TP) with variable physicochemical properties. We identified TPs of five compounds (venlafaxine, telmisartan, valsartan, atorvastatin, and sertraline) by applying suspect and non-targeted data analyses. To our knowledge, the transformation product of atorvastatin was reported for the first time. All others were found in soil or other matrices. Valsartan (formed valsartan acid) and atorvastatin (transformed probably by oxidative decarboxylation of beta, delta dihydroxy heptanoic acid chain to propionic acid) were modified to a relatively large extent. All other compounds identified were only hydroxylated (sertraline and telmisartan) or demethylated (venlafaxine). We estimated the stability and presence of the identified TPs based on the constructed time trends and the ratio between TP formation and degradation rates. We demonstrated how valuable a non-targeted approach can be for complex evaluation of the fate and effect of soil pollutants.

Development of quantitative structure-retention relationship models to improve the identification of leachables in food packaging using non-targeted analysis

Quantitative structure-retention relationship (QSRR) models can be used to predict the chromatographic retention time of chemicals and facilitate the identification of unknown compounds, notably with non-targeted analysis. In this study, QSRR models were developed from the data obtained for 178 pure chemical standards and four types of analytical columns (C18, phenylhexyl, pentafluorophenyl, cyano) in liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). First, different data partitioning ratios and feature selection methods [random forest (RF) and support vector machine (SVM)] were tested to build models to predict chromatographic retention times based on 2D molecular descriptors. The internal and external performances of the non-linear (RF) and corresponding linear predictive models were systematically compared, and RF models resulted in better predictive capacities [p < 0.05, with an average PVE (proportion of variance explained) value of 0.89 ± 0.02] than linear models (0.79 ± 0.03). For each column, the resulting model was applied to identify leachables from actual plastic packaging samples. An in-depth investigation of the top 20 most intense molecular features revealed that all false-positives could be identified as outliers in the QSRR models (outside of the 95% prediction bands). Furthermore, analyzing a sample on multiple chromatographic columns and applying the associated QSRR models increased the capacity to filter false positives. Such an approach will contribute to a more effective identification of unknown or unexpected leachables in plastics (e.g. non-intended added substances), therefore refining our understanding of the chemical risks associated with food contact materials.

Non-target screening for the identification of migrating compounds from reusable plastic bottles into drinking water

Reusable plastic sports bottles are used extensively worldwide, and little is known about the migration of chemicals from the bottles into drinking water. In this study, we investigated the chemical migration into drinking water stored for 24 h in new bottles, used bottles and bottles washed in the dishwasher. Non-target screening (NTS) by liquid-chromatography - high-resolution mass spectrometry (LC-HRMS) was performed to identify these compounds. We detected > 3500 dishwasher related compounds, with 430 showing migration even after subsequent flushing of the bottles. In addition, more than 400 plastic related compounds were detected, with high peaks for oligomers suspected to originate from the biodegradable polyester polycaprolactone, and aromatic amines, which may have been introduced as slip agents or antioxidants. These compounds have never been reported before in bottled water. Most of the identified compounds migrating out of the used bottles were plasticizers, antioxidants or photoinitiators. The presence of photoinitiators are of particular concern, due to possible endocrine disrupting effects. Furthermore, diethyltoluamide (DEET) was detected, which may have been formed from the plasticizer laurolactam. Typically, the dishwashing process enhanced the leaching of plastic related compounds, and even after additional water flushing, the average peak intensity of these compounds was only reduced by half.

Computational Workflow to Study the Diversity of Secondary Metabolites in Fourteen Different Isatis Species

The screening of real features among thousands of ions remains a great challenge in the study of metabolomics. In this research, a workflow designed based on the MetaboFR tool and “feature-rating” rule was developed to screen the real features in large-scale data analyses. Seventy-four reference standards were used to test the feasibility, with 83.21% of real features being obtained after MetaboFR processing. Moreover, the full workflow was applied for systematic characterization of 14 species of the genus Isatis, with the result that 87.72% of real features were retained and 69.19% of the in-source fragments were removed. To gain insights into metabolite diversity within this plant family, 1697 real features were tentatively identified, including lipids, phenylpropanoids, organic acids, indole derivatives, etc. Indole derivatives were demonstrated to be the best chemical markers with which to differentiate different species. The rare existence of indole derivatives in Isatis cappadocica (cap) and Isatis cappadocica subsp. Steveniana (capS) indicates that the biosynthesis of indole derivatives could play a key role in driving the chemical diversity and evolution of genus Isatis. Our workflow provides the foundations for the exploration of real features in metabolomics, and has the potential to reveal the chemical composition and marker metabolites of secondary metabolites in plant fields.

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.

Investigation of the migration of bisphenols from baby bottles and sippy cups

Bisphenol A (BPA) is used as a monomer in a number of consumer products, including baby bottles and sippy cups. Some jurisdictions around the world (including Canada) have regulated the production, advertising or selling polycarbonate baby bottles with BPA. Following the ban, makers have opted for alternative materials to BPA [named BPA analogues, BPAAs], which may not be as safe as promoted. The objective of this project was to conduct a migration study in baby bottles and sippy cups, and analyze 16 BPAAs, as a follow-up on the BPA migration study conducted by Health Canada in 2009. Baby bottles (20 brands) and sippy cups (13 brands) were tested for migration of BPAAs. The most commonly detected analytes in baby bottles were BPS, BPA, BPF, BPAF, BPM and BPTMC with detection frequency (DF) of more than 50%. In sippy cups, only BPA, BPS and BPF were frequently detected. The mean concentration of BPA in baby bottle leachate was 31.5 ng/L in water simulant whereas a 1.4-fold increase was seen in 50% EtOH simulant. Similarly, a 1.4-fold increase was seen in the mean concentration of BPS in 50% EtOH simulant, when compared to the mean concentration of 2.33 ng/L in water simulant. Increasing median concentration was observed for BPA as the ethanol content of the simulant increased (water<10% EtOH<50% EtOH). The concentration of BPS and BPA was higher in sippy cups than that in their matched brand of baby bottles with the 50% EtOH simulant. Although most of the target analytes were detected in baby bottles, their concentrations were low and no migration was observed for any of the analytes with increasing incubation time. Therefore, it is likely that known BPA analogues are not present in the polymers used in the manufacture of most of the baby bottle brands sold in Canada.

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Sensitive and selective UPLC-MS/MS method was developed for simultaneous determination of 16 bisphenols.

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Migration study was conducted on baby bottles and sippy cups purchased on Canadian market.

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BPA and BPS were detected in all baby bottles and sippy cups.

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The study suggests that repeated use of the baby bottles will not increase the leaching of BPA analogues.

An overview of chemical contaminants and other undesirable chemicals in alcoholic beverages and strategies for analysis

The presence of chemical contaminant in alcoholic beverages is a widespread and notable problem with potential implications for human health. With the complexity and wide variation in the raw materials, production processes, and contact materials involved, there are a multitude of opportunities for a diverse host of undesirable compounds to make their way into the final product-some of which may currently remain unidentified and undetected. This review provides an overview of the notable contaminants (including pesticides, environmental contaminants, mycotoxins, process-induced contaminants, residues of food contact material [FCM], and illegal additives) that have been detected in alcoholic products thus far based on prior reviews and findings in the literature, and will additionally consider the potential sources for contamination, and finally discuss and identify gaps in current analytical strategies. The findings of this review highlight a need for further investigation into unwanted substances in alcoholic beverages, particularly concerning chemical migrants from FCMs, as well as a need for comprehensive nontargeted analytical techniques capable of determining unanticipated contaminants.

Non-targeted study of the thermal degradation of tylosin in honey, water and water:honey mixtures

Tylosin A is a macrolide antibiotic used in beekeeping. The aim of the study was to characterise the behaviour of tylosin A in honey after heating and during storage, and to identify its degradation products using a non-targeted approach. In addition, the possibility of a semi-quantification of tylosin B using tylosin A was assessed as a case study for the semi-quantification of degradation products using the parent compounds. The results showed significant degradation of tylosin A in aqueous solution (~96%) as well as in spiked and incurred honey dissolved in water (~50% and ~29%, respectively) after heating at 100°C for 90 min. However, at a lower heating temperature of 70°C, degradation was only observed in water (~31%). When stored at room temperature (27°C) for one year, tylosin A degraded significantly (~47%) in an incurred honey sample. Tylosin B, the only reported degradation product of tylosin A in honey so far, increased significantly in aqueous solution under all treatments, but it only increased in spiked water-honey mixture after heating at 100°C. Two new degradation products, namely 5-O-mycaminosyltylonolide (OMT) and lactenocin, were tentatively identified in water and spiked honey after heating at 100°C. The results of the present study reinforce the conclusion that relying only on the water model or spiked food matrix is not sufficient to understand the thermal degradation of antibiotics in food matrices. Finally, a semi-quantification of tylosin B with a relative error of 20% in an incurred honey sample was possible using the response factor of tylosin A, its parent compound. The results of this study prove that a semi-quantification using the parent compound to quantify its degradation compound can provide satisfactory results, but this will be analyte-dependent.

Suspect screening of plastic-related chemicals in northern pike (Esox lucius) from the St. Lawrence River, Canada

Environmental contaminant monitoring traditionally relies on targeted analysis, and very few tools are currently available to monitor "unexpected" or "unknown" compounds. In the present study, a non-targeted workflow (suspect screening) was developed to investigate plastic-related chemicals and other environmental contaminants in a top predator freshwater fish species, the northern pike, from the St. Lawrence River, Canada. Samples were extracted using sonication-assisted liquid extraction and analyzed by high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (HPLC-QTOF-MS). Ten bisphenol compounds were used to test the analytical performances of the method, and satisfactory results were obtained in terms of instrumental linearity (r² > 0.97), recoveries, (86.53-119.32%), inter-day precision and method detection limits. The non-targeted workflow data processing parameters were studied, and the peak height filters (peak filtering step) were found to influence significantly the capacity to detect and identify trace chemicals in pike muscle extracts. None of the ten bisphenol analogues were detected in pike extracts suggesting the absence of accumulation for these chemicals in pike muscle. However, the non-targeted workflow enabled the identification of diethyl phthalate (DEP) and perfluorooctanesulfonic acid (PFOS) in pike extracts. This approach thus can be also applied to various contaminants in other biological matrices and environmental samples.

Development of a liquid chromatography-quadrupole-time-of-flight-mass spectrometry based method for the targeted and suspect screening of contaminants in the pearl oyster Pinctada imbricata radiata

A rapid method based on solvent extraction followed by direct injection in liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOF-MS) was developed for the targeted and suspect screening of contaminants in the soft tissues of the pearl oyster Pinctada imbricata radiata. The quantification method was first validated for the targeted analysis of 21 contaminants including some pharmaceutically active compounds, with the relative recoveries ranging from 88 to 123%, and method detection limits generally below 1 ng g^-1 on the wet weight (ww) basis. This targeted analysis method was then applied to oyster samples collected around the Qatari coast between 2017/2018, and none of the 21 compounds were detected in these samples. The post-acquisition data treatment based on the accurate mass measurement in both full MS scan and All Ions MS/MS was further used for mining other contaminants in oyster extracts, as well as 21 targeted compounds spiked in oyster extracts (suspect screening). The 21 spiked compounds were identified successfully and the estimated limit of identification for the individual 21 compounds ranged from 0.5 to 117 ng g^-1 ww of oyster tissues. A phthalate, di(2-ethylhexyl) phthalate (DEHP) was identified to be present in oyster extracts from 2018 batches, at a concentration level significantly higher than that in procedure blanks. These results confirmed that high resolution MS data obtained using the targeted method can be exploited through suspect screening workflows to identify contaminants in the tissues of bioindicator mollusks. However, a number of false identifications could be obtained and future work will be on improving the success rate of the correct identifications using this workflow.

Migration of oligomers from a food contact biopolymer based on polylactic acid (PLA) and polyester

Polylactic acid (PLA) is a biopolymer commonly used in food packaging due to its good characteristics, similar to PET. To evaluate the safety of this material, the analysis of the non-intentionally added substances (NIAS) is required. Oligomers are NIAS and their behavior needs a deep study, especially if they migrate to the food. In this work, the analysis of the polymer and the migration to food simulants was carried out. A total dissolution/precipitation procedure was applied to PLA pellets and films, using dichloromethane and ethanol as solvent and antisolvent system respectively. The migration tests were carried out in three liquid simulants to mimic any kind of food. Since oligomers are not present in the positive list of the Directive 10/2011/EC, their concentration must be below the 0.01 mg/kg of food. UPLC-QTOF-MS, with and without ion mobility (IM), was used for the analysis. Thirty-nine different PLA oligomers made of repeated monomer units of [LA] (C₃H₄O₂) and with different structures were identified. They corresponded to cyclic oligomers with [LA]_n structure and two groups of linear oligomers, one with an hydroxyl group, OH-[LA]_n-H, and the other one with an ethoxy group, CH₃-CH₂-O-[LA]_n-H. Cyclic oligomers only appeared in the material and were not present in migration solutions. Linear oligomers HO-[LA]_n-H were already present in the pellets/film and they migrated in a higher extension to aqueous food simulants (EtOH 10% and AcH 3%). However, linear oligomers CH₃-CH₂-O-[LA]_n-H were not present initially in the pellets/film, but were detected in migration to simulants with ethanol content, EtOH 95% and EtOH 10%. Furthermore, 5 cyclic polyester oligomers were identified in migration. Ethanol 95% and ethanol 10% migration solutions were also analyzed by scanning electron microscopy (SEM), and the presence of microstructures that could be attributed to the oligomers migration was found. They could be seen as microplastics.

Optimization of the Data Treatment Steps of a Non-targeted LC-MS-Based Workflow for the Identification of Trace Chemical Residues in Honey

Non-targeted screening (e.g., suspected-target) is emerging as an attractive tool to investigate the occurrence of contaminants in food. The sample preparation and instrument analysis steps are known to influence the identification of analytes with non-targeted workflows, especially for complex matrices. However, for methods based on mass spectrometry, the impact of the post-analysis data treatment (e.g., feature extraction) on the capacity to correctly identify a contaminant at trace level is currently not well understood. The aim of the study was to investigate the influence of seven post-analysis data treatment parameters on the non-targeted identification of trace contaminants in honey using high-performance liquid chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS). Seven compounds reported as veterinary drugs for honeybees were applied as model compounds. Among the parameters studied, the expansion window for chromatogram extraction and the average scans included in the spectra influenced significantly the identification process results. The optimized data treatment was applied to the non-targeted screening of veterinary drugs, pesticides, and other contaminants in 55 honey samples as a proof of concept. Among the 43 compounds included in a library of honey-related compounds that was used for screening, eight compounds were tentatively identified in at least one honey sample. The tentative identity of two of these compounds (tylosin A and hydroxymethylfurfural) was further confirmed with analytical standards. Graphical Abstract.