Challenges in relating concentrations of aromas and tastes with flavor features of foods.

Flavor sensations in food are highly influenced by the aroma and taste compounds. Reviewing the extensive literature of recent years in this field has shown that the reconstitution of flavor based on aroma and taste compounds poses numerous problems. These are of different nature and include among others (a) chemical transformations among these compounds, (b) changes in the concentrations of the compounds responsible for the perceived flavor, (c) interactions among the chemical compounds that enhance or reduce a specific flavor sensation, and finally, (d) the complexity of the different food matrices and its influence in the flavor perception. Another difficulty that flavor scientists must face is how to properly model and visualize the complex relationships existing between the chemical composition of foods and the flavor perception. These problems have repercussions on the reconstitution of the flavor signature of food based on the natural concentrations of its key aroma and taste compounds. Therefore, the main aim of this review is to deal with all these issues to propose potential solutions for a robust transformation in a science-based quality approach.

Ion-Mobility-Derived Collision Cross Section as an Additional Identification Point for Multiresidue Screening of Pesticides in Fish Feed.

Ion mobility spectrometry allows for the measurement of the collision cross section (CCS), which provides information about the shape of an ionic molecule in the gas phase. Although the hyphenation of traveling-wave ion mobility spectrometry (TWIMS) with high-resolution quadrupole time-of-flight mass spectrometry (QTOFMS) has been mainly used for structural elucidation purposes, its potential for fast screening of small molecules in complex samples has not yet been thoroughly evaluated. The current work explores the capabilities of ultrahigh-performance liquid chromatography (UHPLC) coupled to a new design TWIMS-QTOFMS for the screening and identification of a large set of pesticides in complex salmon feed matrices. A database containing TWIMS-derived CCS values for more than 200 pesticides is hereby presented. CCS measurements showed high intra- and interday repeatability (RSD < 1%), and they were not affected by the complexity of the investigated matrices (ΔCCS ≤ 1.8%). The use of TWIMS in combination with QTOFMS was demonstrated to provide an extra-dimension, which resulted in increased peak capacity and selectivity in real samples. Thus, many false-positive detections could be straightforwardly discarded just by applying a maximum ΔCCS tolerance of ±2%. CCS was proposed as a valuable additional identification point in the pesticides screening workflow. Several commercial fish feed samples were finally analyzed to demonstrate the applicability of the proposed approach. Ethoxyquin and pirimiphos-methyl were identified in most of the analyzed samples, whereas tebuconazole and piperonil butoxide were identified for the first time in fish feed samples.

Identification of in vitro and in vivo human metabolites of the new psychoactive substance nitracaine by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

The purpose of this work was to investigate the in vitro metabolism of nitracaine, a new psychoactive substance, using human liver microsome incubations, to evaluate the cytochrome P450 (CYP) enzyme isoforms responsible for the phase-I metabolism and to compare the information from the in vitro experiments with data resulting from an authentic user's urine sample. Accurate mass spectra of metabolites were obtained using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) and were used in the structural identification of metabolites. Two major and three minor phase-I metabolites were identified from the in vitro experiments. The observed phase-I metabolites were formed through N-deethylation, N,N-deethylation, N-hydroxylation, and de-esterification, with CYP2B6 and CYP2C19 being the main enzymes catalyzing their formation. One glucuronidated product was identified in the phase-II metabolism experiments. All of these metabolites are reported for the first time in this study except the N-deethylation product. All the in vitro metabolites except the minor N,N-deethylation product were also present in the human urine sample, thus demonstrating the reliability of the in vitro experiments in the prediction of the in vivo metabolism of nitracaine. In addition to the metabolites, three transformation products (p-nitrobenzoic acid, p-aminobenzoic acid, and 3-(diethylamino)-2,2-dimethylpropan-1-ol) were identified, as well as several glucuronides and glutamine derived of them.

A data-independent acquisition workflow for qualitative screening of new psychoactive substances in biological samples.

Identification of new psychoactive substances (NPS) is challenging. Developing targeted methods for their analysis can be difficult and costly due to their impermanence on the drug scene. Accurate-mass mass spectrometry (AMMS) using a quadrupole time-of-flight (QTOF) analyzer can be useful for wide-scope screening since it provides sensitive, full-spectrum MS data. Our article presents a qualitative screening workflow based on data-independent acquisition mode (all-ions MS/MS) on liquid chromatography (LC) coupled to QTOFMS for the detection and identification of NPS in biological matrices. The workflow combines and structures fundamentals of target and suspect screening data processing techniques in a structured algorithm. This allows the detection and tentative identification of NPS and their metabolites. We have applied the workflow to two actual case studies involving drug intoxications where we detected and confirmed the parent compounds ketamine, 25B-NBOMe, 25C-NBOMe, and several predicted phase I and II metabolites not previously reported in urine and serum samples. The screening workflow demonstrates the added value for the detection and identification of NPS in biological matrices.

In vitro Phase I and Phase II metabolism of α-pyrrolidinovalerophenone (α-PVP), methylenedioxypyrovalerone (MDPV) and methedrone by human liver microsomes and human liver cytosol.

The aim of the present study was to identify the in vitro Phase I and Phase II metabolites of three new psychoactive substances: α-pyrrolidinovalerophenone (α-PVP), methylenedioxypyrovalerone (MDPV), and methedrone, using human liver microsomes and human liver cytosol. Accurate-mass spectra of metabolites were obtained using liquid chromatography-quadrupole time-of-flight mass spectrometry. Six Phase I metabolites of α-PVP were identified, which were formed involving reduction, hydroxylation, and pyrrolidine ring opening reactions. The lactam compound was the major metabolite observed for α-PVP. Two glucuronidated metabolites of α-PVP, not reported in previous in vitro studies, were further identified. MDPV was transformed into 10 Phase I metabolites involving reduction, hydroxylation, and loss of the pyrrolidine ring. Also, six glucuronidated and two sulphated metabolites were detected. The major metabolite of MDPV was the catechol metabolite. Methedrone was transformed into five Phase I metabolites, involving N- and O-demethylation, hydroxylation, and reduction of the ketone group. Three metabolites of methedrone are reported for the first time. In addition, the contribution of individual human CYP enzymes in the formation of the detected metabolites was investigated.

In vitro metabolism of BDE-47, BDE-99, and α-, ß-, γ-HBCD isomers by chicken liver microsomes.

The in vitro oxidative metabolism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), and the individual α-, ß- and γ-hexabromocyclododecane (HBCD) isomers catalyzed by cytochrome P450 (CYP) enzymes was studied using chicken liver microsomes (CLMs). Metabolites were identified using a liquid chromatography-tandem mass spectrometry method and authentic standards for the oxidative metabolites of BDE-47 and BDE-99. Six hydroxylated tetra-BDEs, namely 4-hydroxy-2,2',3,4'-tetrabromodiphenyl ether (4-OH-BDE-42), 3-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (3-OH-BDE-47), 5-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (5-OH-BDE-47), 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE-47), 4'-hydroxy-2,2',4,5'- tetrabromodiphenyl ether (4'-OH-BDE-49), and 2'-hydroxy-2,3',4,4'-tetrabromodiphenyl ether (2'-OH-BDE-66), were identified and quantified after incubation of BDE-47 with CLMs. 4'-OH-BDE-49 was the major metabolite formed. Three hydroxylated penta-BDEs (5'-hydroxy-2,2',4,4',5-pentabromodiphenyl ether (5'-OH-BDE-99), 6'-hydroxy-2,2',4,4',5- pentabromodiphenyl ether (6'-OH-BDE-99), and 4'-hydroxy-2,2',4,5,5'-pentabromodiphenyl ether, 4'-OH-BDE-101, were formed incubating BDE-99 with CLMs. Concentrations of BDE-99 metabolites were lower than those of BDE-47. More than four mono-hydroxylated HBCD (OH-HBCD), more than four di-hydroxylated HBCD (di-OH-HBCD), more than five mono-hydroxylated pentabromocyclododecenes (OH-PBCD), and more than five di-hydroxylated pentabromocyclododecenes (di-OH-PBCD) were detected when α-, ß-, or γ-HBCD were individually incubated with CLMs. Response values (the ratio between the peak areas of the target compound and its internal standard) for OH-HBCD were 1-3 orders of magnitude higher than those for OH-PBCD, di-OH-HBCD, and di-OH-PBCD, suggesting that OH-HBCD might be the major metabolites of α-, ß- and γ-HBCD produced by CLMs. No diastereoisomeric or enantiomeric bioisomerisation was observed incubating α-, ß- or γ-HBCD with CLMs. Collectively, our data suggest that (i) BDE-47 is metabolized at a faster rate than BDE-99 by CLMs, (ii) OH-HBCD are the major hydroxylated metabolites of α-, ß- and γ-HBCD produced by CLMs and (iii) the diastereoisomeric or enantiomeric bioisomerisation of α-, ß- and γ-HBCD is not mediated by chicken CYP enzymes.

UHPLC-HRMS data from non-targeted screening for biotransformation products of cytostatic drug imatinib.

Imatinib is a selective tyrosine kinase inhibitor used to treat chronic myeloid leukemia. It enters the environment by excretion from the body through urine and feces and is transferred with wastewater to a wastewater treatment plant. There, it can be degraded by activated sludge, forming a number of biotransformation products. Presence of imatinib and its potential transformation products in the environment can impose a high risk to aquatic organisms and human health, therefore it is important to obtain knowledge of its environmental fate. The data presented here is a result of a simulated biodegradation of imatinib at two levels of activated sludge using a batch biotransformation setup, with and without carbon source. The data was acquired with UHPLC-HRMS/MS and processed by MzMine2.36 [1]. The dataset presents a table of [M+H]+ features with retention times and corresponding MS/MS data. With development of new data mining tools this data can be used to identify new transformation products of imatinib and with it fully understand its environmental fate and the risk associated with its presence in the environment.

A novel workflow utilizing open-source software tools in the environmental fate studies: The example of imatinib biotransformation.

The aim of this study is to utilize novel and powerful workflows with publicly available tools to efficiently process data and facilitate rapid acquisition of knowledge on environmental fate studies. Taking imatinib (IMA) as an example, we developed an efficient workflow to describe IMA biodegradation with activated sludge (AS) from wastewater treatment plants (WWTP). IMA is a cytostatic pharmaceutical; a selective tyrosine kinase inhibitor used to treat chronic myeloid leukemia. Its reported ecotoxic, endocrine and genotoxic effects imply high risk for aquatic wildlife and human health, however its fate in the environment is not yet well known. The study was conducted in a batch biotransformation setup, at two AS concentration levels and in presence and absence of carbon source. Degradation profiles and formation of IMA transformation products (TPs) were investigated using UHPLC-QqOrbitrap-MS/MS which showed that IMA is readily biodegradable. TPs were determined using multivariate statistical analysis. Eight TPs were determined and tentatively identified, six of them for first time. Hydrolysis of amide bond, oxidation, demethylation, deamination, acetylation and succinylation are proposed as major biodegradation pathways. TP235, the product of amide bond hydrolysis, was detected and quantified in actual wastewaters, at levels around 1 ng/L. This calls for more studies on the environmental fate of IMA in order to properly asses the environmental risk and hazard associated to IMA and its TPs.

Identification of ethoxyquin and its transformation products in salmon after controlled dietary exposure via fish feed.

Ethoxyquin (EQ) is an additive present in fish feed and its fate in fish should be carefully characterized due to food safety concerns regarding this compound. Therefore, the objective of this work was to identify the transformation products (TPs) of EQ in Atlantic salmon. Salmon in independent tanks were given feed containing ethoxyquin concentrations of 0.5 mg/kg, 119 mg/kg or 1173 mg/kg for 90 days. After the feeding trial, salmon fillets were extracted in acetonitrile and analyzed by liquid chromatography with traveling-wave ion mobility spectrometry coupled to high resolution mass spectrometry (UHPLC-TWIMS-QTOFMS). EQ was transferred from the feed to salmon fillets and 23 TPs were characterized, resulting from dimerization, oxygenation, cleavage, cleavage combined with oxygenation, cleavage combined with conjugation, and other uncategorized alterations. Moreover, EQ and some TPs were also detected in commercial salmon randomly sampled from different Norwegian fish farms. This study confirmed that the dimer 1,8'-EQDM was the main TP of EQ and, together with previous research, brought the overall number of characterized TPs to a total of 47.

Aerobic activated sludge transformation of vincristine and identification of the transformation products.

This study aims to identify (bio)transformation products of vincristine, a plant alkaloid chemotherapy drug. A batch biotransformation experiment was set-up using activated sludge at two concentration levels with and without the addition of a carbon source. Sample analysis was performed on an ultra-high performance liquid chromatograph coupled to a high-resolution hybrid quadrupole-Orbitrap tandem mass spectrometer. To identify molecular ions of vincristine transformation products and to propose molecular and chemical structures, we performed data-dependent acquisition experiments combining full-scan mass spectrometry data with product ion spectra. In addition, the use of non-commercial detection and prediction algorithms such as MZmine 2 and EAWAG-BBD Pathway Prediction System, was proven to be proficient for screening for transformation products in complex wastewater matrix total ion chromatograms. In this study eleven vincristine transformation products were detected, nine of which were tentatively identified.

Investigating in-sewer transformation products formed from synthetic cathinones and phenethylamines using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

Recent studies have demonstrated the role of biofilms on the stability of drug residues in wastewater. These factors are pertinent in wastewater-based epidemiology (WBE) when estimating community-level drug use. However, there is scarce information on the biotransformation of drug residues in the presence of biofilms and the potential use of transformation products (TPs) as biomarkers in WBE. The purpose of this work was to investigate the formation of TPs in sewage reactors in the presence of biofilm mimicking conditions during in-sewer transport. Synthetic cathinones (methylenedioxypyrovalerone, methylone, mephedrone) and phenethylamines (4-methoxy-methamphetamine and 4-methoxyamphetamine) were incubated in individual reactors over a 24h period. Analysis of parent species and TPs was carried out using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToFMS). Identification of TPs was done using suspect and non-target workflows. In total, 18 TPs were detected and identified with reduction of ß-keto group, demethylenation, demethylation, and hydroxylation reactions observed for the synthetic cathinones. For the phenethylamines, N- and O-demethylation reactions were identified. Overall, the experiments showed varying stability for the parent species in wastewater in the presence of biofilms. The newly identified isomeric forms of TPs particularly for methylone and mephedrone can be used as potential target biomarkers for WBE studies due to their specificity and detectability within a 24h residence time.

Comprehensive characterization of ethoxyquin transformation products in fish feed by traveling-wave ion mobility spectrometry coupled to quadrupole time-of-flight mass spectrometry.

Feed additives are typically used in intensive farming production over long periods, and hence, they can accumulate in farmed animal tissues. Concerns regarding the use of ethoxyquin as an antioxidant feed additive, have recently arisen due to its potential conversion into a series of transformation products (TPs). The aim of this work was to characterize the TPs of ethoxyquin in fish feed by a novel approach based on the use of traveling-wave ion mobility spectrometry (TWIMS) coupled to high-resolution quadrupole time-of-flight mass spectrometry (QTOFMS). First, ethoxyquin was oxidized under controlled conditions and the generated TPs were added to a comprehensive database. Atlantic salmon feeds were then screened for ethoxyquin TPs using both targeted and untargeted approaches. Twenty-seven TPs were tentatively identified during the oxidation experiments, fifteen of them also being present in the feed samples. In addition, ten other potential TPs were detected in fish feed following the untargeted approach. Thirty-one of these TPs have been reported for the first time in this work through the oxidation experiments and the feed samples. Therefore, this study provides valuable information on the oxidative fate of ethoxyquin in feed, which can be used for future evaluations of potential risk related to this additive.

Screening and identification of per- and polyfluoroalkyl substances in microwave popcorn bags.

Liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToF-MS) was used for the accurate identification (<10ppm) of different polyfluoroalkylphosphates (PAPs) and their intermediate and end degradation products in popcorn bags. Up to 46 per- and polyfluoroalkyl substances (PFASs) and precursors were identified. Moreover, an accurate method based on focused ultrasonic solid-liquid extraction (FUSLE) and a clean-up step with Envi-Carb sorbent was validated and applied to the quantification of 24 PFASs in popcorn bags from over twelve European countries, three American countries and two Asian countries. To the best of our knowledge, this is the first time that identification and quantification of some intermediates of PFAS precursors (different chain length fluorotelomer saturated acids (FTCAs) and fluorotelomer unsaturated acids (FTUCAs)) have been reported. Moreover, different patterns in the microwave popcorn bag composition were observed within the countries; while in European and American countries short chain PFASs were detected, Asian countries still use long chain PFASs.

Biotransformation of 8:2 polyfluoroalkyl phosphate diester in gilthead bream (Sparus aurata).

Polyfluoroalkyl phosphate esters (PAPs) are high production volume surfactants used in the food contact paper and packaging industry. PAPs may transform to persistent perfluoroalkyl carboxylic acids (PFCAs) under biotic conditions, but little is known about their fate and behavior in aquatic organisms. Here we report for the first time on the uptake, tissue distribution, and biotransformation of 8:2 polyfluoroalkyl phosphate diester (8:2 diPAP) in fish. Gilt-head bream (Sparus aurata) were dosed via the diet (8:2 diPAP at 29µg/g) for 7days, during which time 8:2 diPAP and its transformation products were monitored in plasma, liver, muscle, gills, bile and brain. 8:2 diPAP tended to accumulate in liver, plasma and gills, and to a lesser extent in muscle, bile and brain. Several transformation products (observed previously in other organisms) were also observed in most tissues and biofluids, including both saturated and unsaturated fluorotelomer acids (8:2 FTCA, 8:2 FTUCA, 7:3 FTCA), and perfluorooctanoic acid (PFOA). 8:2 FTCA was the major metabolite in all tissues/biofluids, except for bile, where PFOA occurred at the highest concentrations. Unexpectedly high PFOA levels (up to 3.7ng/g) were also detected in brain. Phase 2 metabolites, which have been reported in fish following exposure to fluorotelomer alcohols, were not observed in these experiments, probably due to their low abundance. Nevertheless, the detection of PFOA indicates that exposure to PAPs may be an indirect route of exposure to PFCAs in fish.

Dietary exposure and neurotoxicity of the environmental free and bound toxin ß-N-methylamino-l-alanine.

The growing evidence supporting a link between exposure to the naturally occurring toxin ß-N-methylamino-l-alanine (BMAA) and progressive neurodegenerative diseases, has recently arisen the interest of the scientific community. Latest investigations suggest that dietary exposure to this algal toxin may have been largely underestimated. This paper reviews the state of the art regarding BMAA, with special attention paid to its neurotoxicity, its concentration levels in food, and human exposure. As for other environmental toxins, dietary intake is most likely the main route of exposure to BMAA for the general population. However, data concerning BMAA levels in foodstuffs are still scarce. It is concluded that further investigations on dietary intake and potential human health effects are clearly necessary to assess the risks to public health associated with BMAA exposure. Some critical remarks and recommendations on future research in this area are provided, which may help to identify approaches to reduce dietary BMAA exposure.

Tailored liquid chromatography-mass spectrometry analysis improves the coverage of the intracellular metabolome of HepaRG cells.

Metabolomics protocols are often combined with Liquid Chromatography-Mass Spectrometry (LC-MS) using mostly reversed phase chromatography coupled to accurate mass spectrometry, e.g. quadrupole time-of-flight (QTOF) mass spectrometers to measure as many metabolites as possible. In this study, we optimised the LC-MS separation of cell extracts after fractionation in polar and non-polar fractions. Both phases were analysed separately in a tailored approach in four different runs (two for the non-polar and two for the polar-fraction), each of them specifically adapted to improve the separation of the metabolites present in the extract. This approach improves the coverage of a broad range of the metabolome of the HepaRG cells and the separation of intra-class metabolites. The non-polar fraction was analysed using a C18-column with end-capping, mobile phase compositions were specifically adapted for each ionisation mode using different co-solvents and buffers. The polar extracts were analysed with a mixed mode Hydrophilic Interaction Liquid Chromatography (HILIC) system. Acidic metabolites from glycolysis and the Krebs cycle, together with phosphorylated compounds, were best detected with a method using ion pairing (IP) with tributylamine and separation on a phenyl-hexyl column. Accurate mass detection was performed with the QTOF in MS-mode only using an extended dynamic range to improve the quality of the dataset. Parameters with the greatest impact on the detection were the balance between mass accuracy and linear range, the fragmentor voltage, the capillary voltage, the nozzle voltage, and the nebuliser pressure. By using a tailored approach for the intracellular HepaRG metabolome, consisting of three different LC techniques, over 2200 metabolites can be measured with a high precision and acceptable linear range. The developed method is suited for qualitative untargeted LC-MS metabolomics studies.

Identification of in vitro metabolites of ethylphenidate by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

Ethylphenidate is a new potent synthetic psychoactive drug, structurally related to methylphenidate. Using human liver microsomes and cytosol, we have investigated for the first time the Phase-I and Phase-II in vitro metabolism of ethylphenidate. The structure of the metabolites was elucidated by hybrid quadrupole time-of-flight mass spectrometry. Overall, seven Phase-I, but no Phase-II metabolites were detected. Ethylphenidate underwent hydroxylation forming two primary mono-hydroxylated metabolites and, subsequently, dehydration and ring opening with an additional hydroxylation, forming secondary metabolites. The involvement of different human cytochrome P450 (CYP) enzymes in the formation of ethylphenidate metabolites was investigated using a panel of human recombinant CYPs (rCYPs). rCYP2C19 was the most active recombinant enzyme involved in the formation of all seven ethylphenidate metabolites detected, although other rCYPs (rCYP1A2, rCYP2B6, rCYPC9, rCYP2D6, and rCYP3A4, but not rCYP2E1) played a role in the metabolism of ethylphenidate. All metabolites identified in the present study can be considered as potential specific biomarkers of ethylphenidate in toxicological studies. Additionally, ritalinic acid and methylphenidate were formed by non-enzymatic hydrolysis and trans-esterification, and, therefore, they cannot be considered as (oxidative) metabolites of ethylphenidate. The presence of methylphenidate and ritalinic acid cannot be exclusively associated to the use of ethylphenidate, since methylphenidate is a drug itself and ritanilic acid can be formed from both ethylphenidate and methylphenidate.

Biodegradability of the anticancer drug etoposide and identification of the transformation products.

Etoposide susceptibility to microbiological breakdown was studied in a batch biotransformation system, in the presence or absence of artificial wastewater containing nutrients, salts and activated sludge at two concentration levels. The primary focus of the present study was to study etoposide transformation products by ultra-high performance liquid chromatography coupled to high-resolution hybrid quadrupole-Orbitrap tandem mass spectrometry (MS/MS). Data-dependent experiments combining full-scan MS data with product ion spectra were acquired to identify the molecular ions of etoposide transformation products, to propose the molecular formulae and to elucidate their chemical structures. Due to the complexity of the matrix, visual inspection of the chromatograms showed no clear differences between the controls and the treated samples. Therefore, the software package MZmine was used to facilitate the identification of the transformation products and speed up the data analysis. In total, we propose five transformation products; among them, four are described as etoposide transformation products for the first time. Even though the chemical structures of these new compounds cannot be confirmed due to the lack of standards, their molecular formulae can be used to target them in monitoring studies.

Reactivity of vinca alkaloids during water chlorination processes: Identification of their disinfection by-products by high-resolution quadrupole-Orbitrap mass spectrometry.

Concerns about the presence of anticancer drugs in the environment are rapidly increasing mainly due to their growing use in the developed countries and their known cytotoxic effects. Vinca alkaloids are widely used in cancer therapy; however, very scarce information is available on their occurrence, environmental fate and toxicological effects on aquatic organisms. Even less attention has been paid to their potential transformation products, which can exert higher toxicity than the parent compounds. Thus, in the present work, the reactivity of vincristine, vinblastine, vinorelbine and its metabolite 4-O-deacetyl vinorelbine during water chlorination processes has been investigated for the first time. Under the studied chlorination conditions, vincristine was fairly stable whereas vinblastine, vinorelbine and 4-O-deacetyl vinorelbine were quickly degraded. A total of sixty-five disinfection by-products were tentatively identified by ultra-high performance liquid chromatography coupled to high-resolution hybrid quadrupole-Orbitrap tandem mass spectrometry. Among them, twenty by-products corresponded to mono-chlorinated compounds, eight to di-chlorinated compounds and two to tri-chlorinated compounds, which may be of major environmental concern. Other disinfection by-products involved hydroxylation and oxidation reactions. Although the structures of these by-products could not be positively confirmed due to lack of commercial standards, their chemical formulas and product ions can be added to databases, which will allow their screening in future monitoring studies.

Evaluation of the migration of chemicals from baby bottles under standardised and duration testing conditions.

After the prohibition of bisphenol-A-containing polycarbonate baby bottles in the European Union (EU), alternative materials, such as polypropylene, polyethersulphone, Tritan™ copolyester, etc., have appeared on the market. Based on an initial screening and in vitro toxicity assessment, the most toxic migrating compounds were selected to be monitored and quantified using validated GC- and LC-QqQ-MS methods. The effect of several 'real-life-use conditions', such as microwave, sterilisation and dishwasher, on the migration of different contaminants was evaluated by means of duration tests. These results were compared with a reference treatment (filling five times with pre-heated simulant at 40°C) and with the legal EU 'repetitive-use conditions' (three migrations, 2 h at 70°C). Analysis of the third migration step of the EU repetitive-use conditions (which has to comply with the EU legislative migration limits) showed that several non-authorised compounds were observed in some baby bottles exceeding 10 µg kg(-1). However, all authorised compounds were detected well below their respective specific migration limits (SMLs). The reference experiment confirmed the migration of some of the compounds previously detected in the EU repetitive-use experiment, though at lower concentrations. Analysis of extracts from the microwave and dishwasher experiments showed a reduction in the migration during the duration tests. In general, the concentrations found were low and comparable with the reference experiment. Similar observations were made for the two sterilisation types: steam and cooking sterilisation. However, steam sterilisation seems to be more recommended for daily use of baby bottles, since it resulted in a lower release of substances afterwards. Repeated use of baby bottles under 'real-life' conditions showed no increase in the migration of investigated compounds and, after some time, the migration of these compounds even became negligible.