A Critical Review on Chemical Speciation of Chlorine-Produced Oxidants in Seawater. Part 3: Chromatographic- and Mass Spectrometric-Based Methodologies.

Chlorination of seawater forms a range of secondary oxidative species - collectively called "chlorine-produced oxidants" (CPOs) - having different biocidal, environmental and ecotoxicological properties. The chemical speciation of these compounds is an important step in attempts to assess the effectiveness of chlorination and the potential impacts of its releases. However, comprehensive determination of CPOs represents a significant analytical challenge for many reasons, including the following: CPO species are numerous, highly reactive, with short-lifetimes, difficult to isolate and generally present at low concentrations in a complex salt matrix. Literature review reveals the development of a wide variety of analytical approaches for analysis of CPOs, either collectively via group parameters or individually. A first category of these approaches was the subject of article II (also including sampling and sample preparation) of a trilogy devoted to the chemical speciation of CPOs in seawater. In this third article - which closes the trilogy - emphasis is placed on chromatographic- and mass spectrometric-based approaches. It reviews more than 80 methods, reported from 1981 to date, and thoroughly discusses their principles and performances. Methodologies involving chemical derivatization of CPOs prior to their analysis by gas or liquid chromatography coupled to mass spectrometry provide the best sensitivities, achieving sub-ppb detection limits for species for which suitable derivatization reagents are available. Online mass spectrometry approaches are attracting increasing interest for their ability to analyze multiple CPO species in real time without extensive sample preparation steps, reaching detection limits of about ppb for less polar oxidants. At the current state of metrological development, neither the methodologies based on chromatography nor those based on online mass spectrometry allow complete speciation of CPOs. Future trends and major challenges related to these approaches are discussed.

A Critical Review on Chemical Speciation of Chlorine-Produced Oxidants (CPOs) in Seawater. Part 1: Chlorine Chemistry in Seawater and Its Consequences in Terms of Biocidal Effectiveness and Environmental Impact.

Seawater chlorination has three main industrial uses: disinfection of water and installations, control of biofouling, and preventing the transport of aquatic invasive species. Once in contact with seawater, chlorine reacts rapidly with water constituents (e.g. bromide ions, ammonia, and nitrogen-containing compounds) to form a range of oxidative species (e.g. bromine and N-haloamines), termed "chlorine-produced oxidants" (CPOs) or "total residual oxidants" (TRO). The chemical nature of CPOs and their concentration are a function of two categories of parameters related to treatment modality (e.g. chlorine dose) and water quality (e.g. temperature, pH, ammonia concentration, and organic constituents). The chlorination process may result in continuous or intermittent releases of CPOs in seawater. The reactivity and potential ecotoxicity of CPO species largely depend on their physical and chemical properties. Therefore, evaluation of the biocidal effectiveness of chlorination and its potential impacts requires not only determining the sum of CPOs (via a bulk parameter), but also their chemical speciation. The aim of this article - which is the first of a trilogy dedicated to the chemical speciation of CPOs in seawater - is to provide an overview of current knowledge about chlorine chemistry in seawater and to discuss the biocidal efficacy and the environmental fate of resulting CPOs. The 2nd and 3rd articles delineate a comprehensive and critical review of analytical methods and approaches for the determination of CPOs in seawater.

A Critical Review on Chemical Speciation of Chlorine-Produced Oxidants (CPOs) in Seawater. Part 2: Sampling, Sample Preparation and Non-Chromatographic and Mass Spectrometric-Based Methods.

Chlorination of seawater forms a range of secondary oxidative species, collectively termed "chlorine-produced oxidants" (CPOs). These compounds do not have the same biocidal efficacy, the same fate and behavior in the marine environment, the same potential formation of chlorination by-products (CBPs), nor the same effects on marine organisms. Their chemical speciation is an important step toward an accurate assessment of the effectiveness of chlorination and the potential impacts of its releases, among others. The aim of this paper - which is the second of a trilogy dedicated to the chemical speciation of CPOs in seawater - is to cover all aspects related to CPOs analysis in seawater, from sampling to instrumental determination. First, it discusses the procedures involved in synthesis, storage, and standardization of analytical standards. Second, it deals with sampling and sample preparation, addressing all relevant issues related to these two key steps. Third, it provides a comprehensive and up-to-date overview of the colorimetric, titrimetric, and electrochemical methods used for CPOs determination and thoroughly discusses their advantages and limitations. Finally, this review ends with some recommendations for progress in the field of CPO analysis with the three aforementioned approaches. Chromatographic and mass spectrometric-based methods will be covered in the third and final article (Part III).

Characterization of photoproducts and global ecotoxicity of chlorphenesin: A preservative used in skin care products.

Photolysis experiments of chlorphenesin, used as a preservative in cosmetic products, were performed in aqueous solution and on a cream used in cosmetics. Three by-products resulting from the direct UV-visible photodegradation of chlorphenesin were characterized by chromatography (gas and liquid) coupled with tandem mass spectrometry (GC-MS/MS and LC-HR MS/MS) and found in both solutions. In vitro tests on Vibrio fischeri bacteria showed that the overall ecotoxicity of chlorphenesin increased with increasing irradiation time in both samples. In silico QSAR (Quantitative Structure Activity Relationship) tests were performed using T.E.S.T. (Toxicity Estimation Software Tool). Among the degradation compounds identified, 4-chlorophenol must contribute to the increased ecotoxicity of the photolyzed solution since the in silico LC50 estimated for all tests performed are always lower than those obtained for chlorphenesin.

Les expériences de photolyse de la chlorphénésine, qui s'utilise comme conservateur dans les produits cosmétiques, ont été réalisées en solution aqueuse et sur une crème utilisée dans les cosmétiques. Trois sous-produits résultant de la photodégradation directe UV-visible de la chlorphénésine ont été caractérisés par chromatographie (gaz et liquide) couplée à une spectrométrie de masse en tandem (GC-MS/MS et LC-HR MS/MS) et trouvés dans les deux solutions. Les tests in vitro sur les bactéries Vibrio fischeri ont montré que l'écotoxicité globale de la chlorphénésine augmentait avec l'augmentation du temps d'irradiation dans les deux échantillons. Des tests QSAR (Quantitative Structure Activity Relationship, relation d'activité de structure quantitative) in silico ont été réalisés à l'aide du logiciel T.E.S.T. (Toxicity Estimation Software Tool, outil logiciel d'estimation de la toxicité). Parmi les composés de dégradation identifiés, le 4-chlorophénol doit contribuer à l'augmentation de l'écotoxicité de la solution photolysée puisque la LC50 in silico estimée pour l'ensemble des essais réalisés est toujours inférieure à celle obtenue pour la chlorphénésine.

Significant role of iron on the fate and photodegradation of enrofloxacin.

Enrofloxacin (ENR) belongs to the fluoroquinolone (FQ) antibiotics family, which are contaminants of emerging concern frequently found in effluents. Although many works studying photo-Fenton process for FQ degradation have been reported, there are no reports analysing in deep the effect of iron complexation, as well as other metals, towards FQs' photolysis, which, evidently, also contributes in the overall degradation of the pollutant. Therefore, in this work, we report a comparative study between the photochemical fate of ENR and its complex with Fe(III) under simulated sunlight irradiation. In addition, the effect of dissolved oxygen, self-sensitization process, and H2O2 addition on the studied photochemical systems are also investigated. Results indicate that, for free and iron-complexed ENR, singlet oxygen (1O2) is generated from the interaction of its triplet state with ground state oxygen. Half-life time (t1/2) of ENR under sun simulated conditions is estimated to be around 22 min, while complexation with iron enhances its photostability, leading to a t1/2 of 2.1 h. Such finding indicates that at least the presence of iron, might notably increase the residence time of these pollutants in the environment. Eventually, only with the addition of H2O2, the FQ-iron complex is efficiently degraded due to photo-Fenton process even at circumneutral pH values due to the high stability of the formed complex. Finally, after LC/FT-ICR MS analysis, 39 photoproducts are detected, of which the 14 most abundant ones are identified. Results indicate that photoproducts formation is pH and iron dependent.

Challenges and opportunities for on-line monitoring of chlorine-produced oxidants in seawater using portable membrane-introduction Fourier transform-ion cyclotron resonance mass spectrometry.

The present study reports the first evaluation of a MIMS device equipped with a high-resolution Fourier transform-ion cyclotron resonance mass spectrometer (FT-ICR MS) for comprehensive speciation of chlorine-produced oxidants (CPO) in seawater. A total of 40 model compounds were studied: 4 inorganic haloamines (mono-, di-, and trichloramine and monobromamine), 22 organic N-haloamines, 12 N-haloamino acids, and 2 free oxidants (HOCl/ClO- and HOBr/BrO-). The main key factors influencing the analytes' introduction and their detection were optimized. Under optimized conditions, the rise and fall times of the MIMS signal ranged from 8 to 79 min and from 7 to 73 min, respectively, depending on the compound. Free oxidants and N-haloamino acids, which are ionic or too polar at seawater pH, hardly crossed the membrane, and MIMS analysis was thus unsuitable. Nevertheless, better enrichment and therefore better sensitivity were achieved with organic N-haloamines than with inorganic haloamines. The observed detection limits ranged from tens of µM to sub-µM levels. Oxidant decomposition occurred inside the MIMS device, at a higher rate for N-bromamines than for chlorinated analogues.Graphical abstract.

Study of the photoinduced transformations of maprotiline in river water using liquid chromatography high-resolution mass spectrometry.

Maprotiline was identified as a compound of potential interest further to a suspect screening test carried out for a list of more than 40,000 substances based on specific occurrence, hazard and risk indicators. Despite the high frequency of appearance of this drug in wastewater treatment stations, his environmental fate is still unknown. Herein, we investigated for the first time the maprotiline degradation pathways in river water spiked with the drug at a concentration close to those detected in natural waters. Preliminary photocatalytic experiments in ultrapure water produced 32 transformation products (TPs) resulted mainly from the multiple hydroxylation/oxidation in different positions of the drug molecule. From the river water experiments, 12 TPs were formed by photolysis matching with those observed in ultrapure water experiments, and 2 were also formed resulted from biotic degradation. Employing HPLC-HRMS, we were able to elucidate the chemical structures of TPs and assess the overall degradation mechanism. Preliminary bioassays suggested lower toxicity of TPs relatively to the parent compound.

SPIX: A new software package to reveal chemical reactions at trace amounts in very complex mixtures from high-resolution mass spectra dataset.

RATIONALE: High-resolution mass spectrometry based non-targeted screening has a huge potential for applications in environmental sciences, engineering and regulation. However, it produces large datasets for which full appropriate processing is a real challenge; the development of processing software is the last building-block to enable large-scale use of this approach. METHODS: A new software application, SPIX, has been developed to extract relevant information from high-resolution mass spectral datasets. Dealing with intrinsic sample variability and reducing operator subjectivity, it opens up opportunities and promising prospects in many areas of analytical chemistry. SPIX is freely available at: http://spix.webpopix.org. RESULTS: Two features of the software are presented in the field of environmental analysis. An example illustrates how SPIX reveals photodegradation reactions in wastewater by fitting kinetic models to significant changes in ion abundance over time. A second example shows the ability of SPIX to detect photoproducts at trace amounts in river water, through comparison of datasets from samples taken before and after irradiation. CONCLUSIONS: SPIX has shown its ability to reveal relevant modifications between two series of large datasets, allowing, for instance, the study of the consequences of a given event on a complex substrate. Most of all - and it is to our knowledge the only software currently available allowing this - it can reveal and monitor any kind of reaction in all types of mixture.

UV-visible photodegradation of naproxen in water - Structural elucidation of photoproducts and potential toxicity.

The UV-visible photodegradation of Naproxen (6-methoxy-α-methyl-2-naphthaleneacetic acid, CAS: 22204-53-1), one of the most used and detected non-steroidal anti-inflammatory drugs (NSAIDs) in the world, and its ecotoxicological consequences were investigated in an aqueous medium. The photo-transformation products were analyzed and the structures of photoproducts were elucidated using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) and high-performance liquid chromatography coupled with ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (LC-FTICR-MS). Seven photoproducts were detected and characterized, photo-transformation mechanisms have been postulated to rationalize their formation under irradiation. In silico Q.S.A.R. (Quantitative Structure-Activity Relationship) toxicity predictions were performed with the Toxicity Estimation Software Tool (T.E.S.T.) and in vitro assays were carried out on Vibrio fischeri bacteria. Some of the obtained photoproducts exhibit higher potential toxicity than Naproxen itself but the whole toxicity of the irradiated solution is not of major concern.

How to select relevant metabolites based on available data for parent molecules: Case of neonicotinoids, carbamates, phenylpyrazoles and organophosphorus compounds in French water resources.

The presence of pesticide in water resources is a topical issue in France as in many other countries. Resources can be contaminated by current-used pesticides and their metabolites but also by molecules banned 50 years ago. The number of reported studies on the impact of these substances on human health and environment increases every day. Currently, pesticides and their relevant degradation products are subjected to the European regulation for water intended for human consumption. It sets an individual quality limit of 0.1 µg/L, and another of 0.5 µg/L for the sum of their concentrations. The constant improvement of analytical methods allows laboratories to detect pesticides, at lower and lower concentrations but also more and more metabolites. However, regulation does not provide a national indicative metabolites list to be monitored. Each regional health agency offers their own list based on local agricultural practices and quantities of pesticides sold. This article reports a prioritization method allowing to identify new metabolites to be monitored in water resources, along drinking water treatment plants and in treated water; it describes its application in France in order to anticipate possible non-compliance with raw water and treated water and to provide solutions upstream of changes in sanitary control. This methodology has been developed to rank pesticides and to select the corresponding metabolites by combining three main criteria: use (sale and type of use), toxicity, and environmental fate (based on physical and chemical properties). Prioritization method was applied to four families of pesticides: carbamates, organophosphorus compounds, phenylpyrazoles and neonicotinoids, for which there is a real lack of knowledge as regards the occurrence of their metabolites in metropolitan France. 146 pesticides have been prioritized. The first 50 molecules were considered allowing the identification of 72 metabolites to be monitored in water resources and along drinking water treatment plants.

Laboratory scale UV-visible degradation of acetamiprid in aqueous marketed mixtures - Structural elucidation of photoproducts and toxicological consequences.

Acetamiprid is a neonicotinoid pesticide, which is extensively used on agricultural crops, but has a high toxic effect on beneficial insects and the human body. It is exposed to sunlight irradiation on crops but also in surface waters where it is found at a high level due to its resistance to common water treatments. The aim of the present work was to study the UV-visible photodegradation of acetamiprid, alone and in two marketed mixtures (Polysect Ultra SL® and Roseclear Ultra®). Ten photoproducts were characterized using LC-HR-MS/MS analysis. Photodegradation pathways were proposed based on the chemical structures of photoproducts and kinetic measurements; a matrix effect has been evidenced for commercial mixtures. Most photoproducts exhibit potential developmental toxicity twice higher than that of the parent compound. Regarding potential mutagenicity, all photoproducts are less toxic than acetamiprid. Estimated oral rat LD50 values show that the potential toxicities of photoproducts are similar or lower than that of acetamiprid. In vitro tests on Vibrio fischeri bacteria showed that the ecotoxicities of marketed mixtures are significantly higher than that of acetamiprid in aqueous solution; they slightly increase after UV-light exposure.

Photodegradation of benzisothiazolinone: Identification and biological activity of degradation products.

The photodegradation of benzisothiazolinone was studied in water under UV-Vis irradiation and led to fourteen photoproducts. Chemical structures of these compounds were elucidated using GC-MS, LCMS/MS, and FT-ICR-MS experiments. Based on the chemical structures determined and their appearance order, a photo induced-degradation mechanism of benzisothiazolinone has been proposed, which combines isomerization, oxidation, hydroxylation, hydrolysis, and elimination processes. In silico tests on mutagenicity, Fathead minnow LC50 and oral rat LD50 were carried out to estimate the toxicity of the photoproducts. Compared with experimental data, the calculated oral rat LD50 values were found to be the most relevant and thus used for toxicity estimation. The photoproducts including a phenolic or a sulfino group or both functions were found potentially more toxic than benzisothiazolinone.

Determination of monochloramine dissipation kinetics in various surface water qualities under relevant environmental conditions - Consequences regarding environmental risk assessment.

A total 190 experiments were performed to study the dissipation kinetics of monochloramine (NH2Cl, CAS no 10599-90-3) in surface water samples from six rivers (Loire, Rhône, Meuse, Garonne, Seine and Moselle) and an artificial reservoir (Mirgenbach), all located in France. Experiments were conducted in an open reactor, under relevant controlled environmental conditions. The impact of various parameters such as initial NH2Cl concentration, temperature, pH, presence of sediments, sampling site and collection period was investigated. It was found that NH2Cl dissipated rapidly without any lag phase, and that decay follows an apparent first-order kinetics (r2 > 0.99). Presence of sediment greatly accelerated decay. Half-lives were generally <1 h in river water in presence of natural sediment, but of several hours without sediment. The impact of pH was low for the normal river water pH range. However, increase in temperature significantly accelerated decay. The combination of high initial NH2Cl concentrations and elevated temperatures generally gives half-lives similar to those obtained at lower temperatures and lower concentrations. Short half-lives (0.06 to 1.50 h) were found in all the surface waters examined, regardless of geographic location of sampling site or collection period, indicating no temporal or site-specific effects on NH2Cl dissipation. Decay was slightly faster at lower initial concentrations, which supports extrapolation of half-lives measured in this study to a wide range of environmental concentrations. It can thus be assumed that NH2Cl degradation in river and reservoir waters is mainly determined by presence of sediments and temperature.

Tracking Monochloramine Decomposition in MIMS Analysis.

Membrane-introduction mass spectrometry (MIMS) has been presented as one of the promising approaches for online and real-time analysis of monochloramine (NH2Cl) in diverse matrices such as air, human breath, and aqueous matrices. Selective pervaporation of NH2Cl through the introduction membrane overcomes the need for sample preparation steps. However, both the selectivity and sensitivity of MIMS can be affected by isobaric interferences, as reported by several researchers. High-resolution mass spectrometry helps to overcome those interferences. Recent miniaturization of Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR MS) technology coupled to the membrane-introduction system provides a potent tool for in field analysis of monochloramine in environmental matrices. Monochloramine analysis by MIMS based FT-ICR MS system demonstrated decomposition into ammonia. To further clarify the origin of this decomposition, headspace analyses after bypassing the membrane were undertaken and showed that monochloramine decomposition was not exclusively related to interactions within the membrane. Adsorption inside the MIMS device, followed by surface-catalyzed decomposition, was suggested as a plausible additional mechanism of monochloramine decomposition to ammonia.

Development and validation of a multiclass method for the determination of organohalogen disinfectant by-products in water samples using solid phase extraction and gas chromatography-tandem mass spectrometry.

An analytical method employing solid phase extraction (SPE) and gas chromatography-tandem mass spectrometry (GC-MS/MS) has been developed for quantitative determination of twenty-six organohalogen disinfectant by-products (OXBPs) in water samples. Target analytes include four trihalomethanes (THMs), four iodohalomethanes (I-HMs), one haloacetaldehyde (HAL), six haloketones (HKs), four halonitromethanes (HNMs), and seven haloacetonitriles (HANs). The sample preparation procedure includes pretreatment with ascorbic acid to quench residual oxidants, followed by analyte enrichment using solid-phase extraction. Five SPE sorbents were tested. The best results for the majority of target analytes were obtained using a styrene-divinylbenzene copolymer phase and methyl tert-butyl ether (MTBE) as the elution agent. GC-MS analysis was performed using electron ionization (EI) and selected reaction monitoring (SRM) for analyte detection. The performance of the method was assessed according to the French standard NF T90-210. The method showed LOQs ranging from 3 to 3000 ng L-1. The applicability of the method has been demonstrated by analyzing both river water and tap water samples. The OXBPs detected most often in the tap water were dibromochloromethane (in 100% of the samples, 4.3-4.7 µg L-1), bromodichloromethane (100%, 1.3-1.7 µg L-1), tribromomethane (100%, 0.8-4.4 µg L-1), trichloromethane (100%, 0.6-0.7 µg L-1), dibromoacetonitrile (75%, 0.5-0.9 µg L-1), with dichloroacetonitrile and 1,1,1-trichloro-2-propanone detected at concentrations around the LOQ levels. In the treated river water samples, the only OXBPs measured at levels above the limit of quantification were trichloromethane and 1,1,1-trichloro-2-propanone. To the best of our knowledge, this is the first SPE-GC-MS/MS method enabling the analysis of an extensive list of OXBPs.

A sensitive and specific solid-phase extraction-gas chromatography-tandem mass spectrometry method for the determination of 11 haloacetic acids in aqueous samples.

A method for the analysis of 11 haloacetic acids in water samples has been developed. It involves enrichment of the target analytes from water samples by solid-phase extraction, derivatization to methyl esters, and gas chromatography coupled with tandem mass spectrometry determination. Gas chromatography conditions were optimized for a good separation of all haloacetic acids in a short runtime. Data were acquired in the multiple reaction monitoring mode. Six solid-phase extraction sorbents among the most widely used in environmental analysis were tested. Bakerbond SDB was retained because it has been shown to provide the best results for a large class of targeted haloacetic acids. The performances of the developed method have been assessed according to the French Standard NF T 90-210. The calibration curves for all the studied haloacetic acids had consistent slopes with r2 values > 0.99. Quantification limits between 0.01 and 0.50 µg l-1 were achieved. Satisfactory repeatability (relative standard deviation ≤ 14.3%) and intermediate precision (relative standard deviation ≤ 15.7%) were obtained. Applied to the analysis of 15 untreated water samples collected from three rivers, the method allowed the detection of five haloacetic acids including monochloroacetic acid (in 100% of the samples, <0.5-1.85 µg l-1), dichloroacetic acid (87%, <0.05-0.22 µg l-1), trichloroacetic acid (93%, <0.05-0.52 µg l-1), dibromoacetic acid (53%, <0.01-0.40 µg l-1), tribromoacetic acid (20%, <0.05-0.14 µg l-1), and bromodichloroacetic acid (6%, < 0.05 µg l-1).

Ultraviolet-visible phototransformation of dehydroacetic acid - Structural characterization of photoproducts and global ecotoxicity.

RATIONALE: The present work is devoted to the structural elucidation of by-products issued from the direct ultraviolet-visible (UV-vis) irradiation of dehydroacetic acid (DHA) in solution and in cosmetic emulsion. METHODS: Analyses were carried out using gas chromatography coupled with ion trap mass spectrometry and by high-performance liquid chromatography coupled with ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (LC/UHRMS). The potential toxicities of by-products were estimated by in silico calculations based on a QSAR (Quantitative Structure-Activity Relationship) approach and by in vitro bioassays conducted on Vibrio fischeri bacteria. RESULTS: Three photoproducts were detected by LC/MS while one photoproduct was detected by GC/MS. The first photoproduct (PP1) corresponds to an isomer of DHA while two isomeric compounds correspond to dimeric structures. The oral rat LD50 of PP1 was evaluated to be 4.5 times lower than that of the parent molecule which classes it in the category 'moderately toxic' on the Hodge and Sterne toxicity classification. In vitro assays on Vibrio fischeri bacteria showed that the global ecotoxicity of the DHA solution increases with irradiation time. CONCLUSIONS: With the exception of one photoproduct, the structures proposed for the photoproducts on the basis of mass spectral interpretation have not been reported in previous studies. All photoproducts, with the exception of dimers, were detected after irradiation in the cosmetic emulsion. This result shows that personal care products containing DHA must be protected from direct sunlight to prevent photodegradation.

Determination of adsorbable organic halogens in surface water samples by combustion-microcoulometry versus combustion-ion chromatography titration.

Adsorbable Organic Halogen (AOX) is an analytical parameter of considerable interest since it allows to evaluate the amount of organohalogen disinfection by-products (OXBPs) present in a water sample. Halogen speciation of AOX into adsorbable organic chlorine, bromine and iodine, respectively AOCl, AOBr and AOI, is extremely important since it has been shown that iodinated and brominated organic by-products tend to be more toxic than their chlorinated analogues. Chemical speciation of AOX can be performed by combustion-ion chromatography (C-IC). In the present work, the effectiveness of the nitrate wash according to ISO 9562 standard method protocol to eliminate halide ions interferences was firstly examined. False positive AOX values were observed when chloride concentration exceeded 100 ppm. The improvements made to the washing protocol have eliminated chloride interference for concentrations up to 1000 ppm. A C-IC method for chemical speciation of AOX into AOCl, AOBr, and AOI has been developed and validated. The most important analytical parameters were investigated. The following optimal conditions were established: an aqueous solution containing 2.4 mM sodium bicarbonate/2.0 mM sodium carbonate, and 2% acetone (v/v) as mobile phase, 2 mL of aqueous sodium thiosulfate (500 ppm) as absorption solution, 0.2 mL min-1 as water inlet flow rate for hydropyrolysis, and 10 min as post-combustion time. The method was validated according to NF T90-210 standard method. Calibration curves fitted through a quadratic equation show coefficients of determination (r2) greater than 0.9998, and RSD less than 5%. The LOQs were 0.9, 4.3, and 5.7 µg L-1 Cl for AOCl, AOBr, and AOI, respectively. The accuracy, in terms of relative error, was within a ±â€¯10% interval. The applicability of the validated method was demonstrated by the analysis of twenty four water samples from three rivers in France. The measurements reveals AOX amounts above 10 µg L-1 Cl in all untreated samples, suggesting the presence of organohalogen compounds in the sampled rivers. On weight concentration basis, AOCl accounted for 77-100% of AOX in the treated water samples. A good agreement between the conventional AOX method and the developed C-IC method was found.

UV-vis degradation of α-tocopherol in a model system and in a cosmetic emulsion-Structural elucidation of photoproducts and toxicological consequences.

The UV-vis photodegradation of α-tocopherol was investigated in a model system and in a cosmetic emulsion. Both gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) and high performance liquid chromatography coupled with ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (LC-UHR-MS) were used for photoproducts structural identification. Nine photoproduct families were detected and identified based on their mass spectra and additional experiments with α-tocopherol-d9; phototransformation mechanisms were postulated to rationalize their formation under irradiation. In silico QSAR (Quantitative Structure Activity Relationship) toxicity predictions were conducted with the Toxicity Estimation Software Tool (T.E.S.T.). Low oral rat LD50 values of 466.78mgkg-1 and 467.9mgkg-1 were predicted for some photoproducts, indicating a potential toxicity more than 10 times greater that of α-tocopherol (5742.54mgkg-1). In vitro assays on Vibrio fischeri bacteria showed that the global ecotoxicity of the α-tocopherol solution significantly increases with irradiation time. One identified product should contribute to this ecotoxicity enhancement since in silico estimations for D. magna provide a LC50 value 4 times lower than that of the parent molecule.

Photodegradation of cyprodinil under UV-visible irradiation - chemical and toxicological approaches.

RATIONALE: Cyprodinil is a fungicide active on grapes, strawberries, tomatoes, and many other fruits. Under UV-visible irradiation, it undergoes photodegradation through various processes to form transformation products (TPs) whose structures and potential toxicities are unknown. The structures of the TPs were elucidated by comparing the photodegradation of cyprodinil and cyprodinil-D5 . The potential toxicities of these compounds were compared with that of cyprodinil. METHODS: Aqueous solutions of cyprodinil were irradiated in a reactor equipped with a mercury vapor lamp. Analyses were carried out using high-performance liquid chromatography coupled to a quadrupole time-of-flight (QTOF) mass spectrometer or to a SolarixXR 9.4 Tesla Fourier transform (FT) mass spectrometer. High-resolution mass measurements, MS/MS and isotopic labeling experiments allowed structural elucidation of the cyprodinil TPs. The toxicities were estimated by three tests in silico using the TEST software and in vitro bioassays using Vibrio fischeri bacteria. These bioassays were carried out on irradiated solution for several exposure times and non-irradiated solutions. RESULTS: The structures of 19 photoproducts were characterized by LC/HRMS/MS after 4 h of irradiation of a cyprodinil aqueous solution. The use of cyprodinil-D5 allowed the TPs to be characterized with more confidence. Knowing the structure of the TPs allows the estimation of their potential toxicities by in silico tests. Most of the photoproducts are potentially more toxic than the parent compound, based on the oral rat LD50 values, and most of them might induce more developmental and mutagenic toxicities. In vitro assays on Vibrio fischeri bacteria showed that the global ecotoxicity of the cyprodinil solution significantly increases with irradiation time. CONCLUSIONS: Structures of photoproducts were characterized after irradiation of a cyprodinil aqueous solution combining LC/HRMS, LC/HRMS/MS and the use of a labeled compound. Their formations imply several photodegradation reactions, namely direct bond cleavages, cyclization, isomerization and hydroxylation. Most of the TPs exhibit a toxicity significantly higher than that of the parent molecule. Copyright © 2016 John Wiley & Sons, Ltd.