Differential global profiling as a new analytical strategy for revealing micropollutant treatment by-products: application to ethinylestradiol and chlorination water treatment

Electrochemical degradation of 17α-ethinylestradiol: Transformation products, degradation pathways and in vivo assessment of estrogenic activity

Conventional water treatment methods are not efficient in eliminating endocrine disrupting compounds (EDCs) in wastewater. Electrochemical Advanced Oxidation Processes (eAOPs) offer a promising alternative, as they electro-generate highly reactive species that oxidize EDCs. However, these processes produce a wide spectrum of transformation products (TPs) with unknown chemical and biological properties. Therefore, a comprehensive chemical and biological evaluation of these remediation technologies is necessary before they can be safely applied in real-life situations. In this study, 17α-ethinylestradiol (EE2), a persistent estrogen, was electrochemically degraded using a boron doped diamond anode with sodium sulfate (Na₂SO₄) and sodium chloride (NaCl) as supporting electrolytes. Ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry was used for the quantification of EE2 and the identification of TPs. Estrogenic activity was assessed using a transgenic medaka fish line. At optimal operating conditions, EE2 removal reached over 99.9% after 120 min and 2 min, using Na₂SO₄ and NaCl, respectively. The combined EE2 quantification and in vivo estrogenic assessment demonstrated the overall estrogenic activity was consistently reduced with the degradation of EE2, but not completely eradicated. The identification and time monitoring of TPs showed that the radical agents readily oxidized the phenolic A-ring of EE2, leading to the generation of hydroxylated and/or halogenated TPs and ring-opening products. eAOP revealed to be a promising technique for the removal of EE2 from water. However, caution should be exercised with respect to the generation of potentially toxic TPs.

Clay-catalyzed ozonation of endocrine-disrupting compounds in solvent-free media - to better understand soil catalytic capacity

An original approach never tackled so far allowed correlating the basicity and hydrophilic character of clay catalysts to surface interaction with 17α-Ethinylestradiol (EE2) during ozonation in water. The clay catalysts were found to behave specifically according to their silica/alumina ratio like soils in natural oxidative processes. Acid-activated bentonites (HMt) and ion-exchanged montmorillonite (NaMt and Fe(ii)Mt) showed catalytic activity in the ozonation of 17α-ethinylestradiol (EE2) in aqueous media. In the absence of catalysts, the degradation of (EE2) reached 72% after one minute of ozonation and 99.5% after 60 minutes. In the presence of Fe(ii)Mt, EE2 degradation (96%) was achieved after only one minute of ozonation. Under similar conditions, almost total degradation to 99.99% was registered in 15 minutes of ozonation but without total mineralization of the intermediates. Moderately acid-activated bentonites exhibited higher activity affording total mineralization within a short period of ozonation. The catalytic activity of clay catalysts was found to correlate with their surface basicity and hydrophilic character. The results obtained herein allow understanding soil behavior in natural oxidative degradation of organic molecules and envisaging effective soil-based catalysts with surface properties judiciously tailored according to the nature of organic pollutants in solvent free media.

Determination of emerging chlorinated byproducts of diazepam in drinking water

Diazepam (DZP) is often found in source water and drinking water at dozens of nanograms per liter levels. The transformation of DZP in water chlorination disinfection process has aroused new concern because the toxic disinfection byproducts (DBPs) might be produced. However, the DBPs of DZP have not been fully identified, and their occurrence levels in drinking water have not been reported. In our chlorination experiment, five emerging DBPs of diazepam: (5-chloro-2-(methylamino) phenyl) (phenyl)methanone (BP-246), 6-chloro-1-methyl-4-phenylquinazolin-2(1H)-one (BP-271), N-(2-benzoyl-4,6-dichlorophenyl)formamide (BP-294), methyl-(2-benzoyl-4-chlorophenyl) (methyl)carbamate (BP-304 (1)) and 6-chloro-4-methoxy-1-methyl-4-phenyl-1,4-dihydro2H -benzo[d][1,3]oxazin-2-one (BP-304 (2)), were tentatively identified by high-resolution mass spectrometry and further characterized by nuclear magnetic resonance spectroscopy. We developed a trace analytical method for the analysis of these five DBPs in drinking water based on solid-phase extraction (SPE) followed liquid chromatography coupled with electrospray ionization tandem mass spectrometric detection. Ultrahigh sensitivities were achieved with limits of detection as low as 7 pg per liter. The recoveries at different spiking levels were all higher than 80% except for that of BP-246. Four of the DBPs and DZP were detected in real drinking water samples at concentrations ranging from several to dozens of nanograms per liter with relatively high detection frequencies. This is the first report on the existence of DZP-DBPs in drinking water. The method and results will be useful for further studies on the occurrence, toxicity, human exposure and control measures of these DBPs.

A non-target approach to identify disinfection byproducts of structurally similar sulfonamide antibiotics

There is growing concern over the formation of new types of disinfection byproducts (DBPs) from pharmaceuticals and other emerging contaminants during drinking water production. Free chlorine is a widely used disinfectant that reacts non-selectively with organic molecules to form a variety of byproducts. In this research, we aimed to investigate the DBPs formed from three structurally similar sulfonamide antibiotics (sulfamethoxazole, sulfathiazole, and sulfadimethoxine) to determine how chemical structure influences the types of chlorination reactions observed. We conducted free chlorination experiments and developed a non-target approach to extract masses from the experimental dataset that represent the masses of candidate DBPs. Structures were assigned to the candidate DBPs based on analytical data and knowledge of chlorine chemistry. Confidence levels were assigned to each proposed structure according to conventions in the field. In total, 11, 12, and 15 DBP structures were proposed for sulfamethoxazole, sulfathiazole, and sulfadimethoxine, respectively. The structures of the products suggest a variety of reaction types including chlorine substitution, SC cleavage, SN hydrolysis, desulfonation, oxidation/hydroxylation, and conjugation reactions. Some reaction types were common to all of the sulfonamide antibiotics, but unique reaction types were also observed for each sulfonamide antibiotic suggesting that selective prediction of DBP structures of other sulfonamide antibiotics based on chemical structure is unlikely to be possible based on these data alone. This research offers an approach to comprehensively identify DBPs of organic molecules and fills in much needed data on the formation of specific DBPs from three environmentally relevant sulfonamide antibiotics.

Occurrence of halogenated transformation products of selected pharmaceuticals and personal care products in secondary and tertiary treated wastewaters from southern California

Final effluent samples from 10 southern California (United States) wastewater treatment facilities, employing four distinct treatment schemes, were surveyed for selected pharmaceuticals, personal care products (PPCPs), alkylphenols, and 21 of their halogenated disinfection byproducts. Chlorinated and brominated standards and isotopically labeled internal standards were synthesized and purified to confirm and more accurately quantify selected disinfection byproducts of salicylic acid, bisphenol A, gemfibrozil, naproxen, diclofenac, technical 4-nonylphenol, and 4-tert-octylphenol using high-performance liquid chromatography and tandem mass spectrometry. Concentrations of parent compounds ranged from <10 to 3830 ng/L (gemfibrozil), and those of chloro/bromo byproducts ranged from <4 to 370 ng/L (dibromo nonylphenol). The highest concentrations of parent compounds were measured in effluent that was not subjected to tertiary treatment. The chlorinated and brominated byproduct concentration may be affected by the influent concentration of parent compounds, hydraulic retention times, and chlorine contact times. Salicylic acid was readily halogenated, which is evident from the ratio of halogenated to nonhalogenated species. There were no measured chlorinated byproducts of bisphenol A despite occasionally high concentrations of the parent compound. Not surprisingly, higher concentrations of most brominated species were measured in the treatment plant with the highest bromide concentrations. These results demonstrate the occurrence of novel halogenated byproducts of PPCPs that have limited toxicological data and significant uncertainty with regard to their risk to ecological systems.

Chlorination of bisphenol A: non-targeted screening for the identification of transformation products and assessment of estrogenicity in generated water

Besides the performance of water treatments on the removal of micropollutants, concern about the generation of potential biologically active transformation products has been growing. Thus, the detection and structural elucidation of micropollutants transformation products have turned out to be major issues to evaluate comprehensively the efficiency of the processes implemented for drinking water treatment. However, most of existing water treatment studies are carried out at the bench scale with high concentrations and simplified conditions and thus do not reflect realistic conditions. Conversely, this study describes a non-targeted profiling approach borrowed from metabolomic science, using liquid chromatography coupled to high-resolution mass spectrometry, in order to reveal potential chlorination products of bisphenol A (BPA) in real water samples spiked at 50μgL(-1). Targeted measurements first evidenced a fast removal of BPA (>99%) by chlorination with sodium hypochlorite (0.8mgL(-1)) within 10min. Then, the developed differential global profiling approach enabled to reveal 21 chlorination products of BPA. Among them, 17 were brominated compounds, described for the first time, demonstrating the potential interest of this innovative methodology applied to environmental sciences. In parallel to the significant removal of BPA, the estrogenic activity of water samples, evaluated by ER-CALUX assay, was found to significantly decrease after 10min of chlorination. These results confirm that chlorination is effective at removing BPA in drinking water and they may indicate that the generated compounds have significantly lower estrogenic activity.

Differential chemical profiling to identify ozonation by-products of estrone-sulfate and first characterization of estrogenicity in generated drinking water

For a few years, the concern of water treatment companies is not only focused on the removal of target micropollutants but has been extended to the investigation of potential biologically active by-products generated during the treatment processes. Therefore, some methods dedicated to the detection and structural characterization of such by-products have emerged. However, most of these studies are usually carried out under simplified conditions (e.g. high concentration levels of micropollutants, drastic treatment conditions, use of deionized or ultrapure water) and somewhat unrealistic conditions compared to that implemented in water treatment plants. In the present study, a real field water sample was fortified at the part-per-billion level (50 μg L(-1)) with estrone-3-sulfate (E1-3S) before being ozonated (at 1 mg L(-1)) for 10 min. In a first step, targeted measurements evidenced a degradation of the parent compound (>80%) in 10 min. Secondly, a non-targeted chemical profiling approach derived from metabolomic profiling studies allowed to reveal 11 ozonation by-products, among which 4 were found predominant. The estrogenic activity of these water samples spiked with E1-3S before and after treatment was assessed by the ER-CALUX assay and was found to decrease significantly after 10 min of ozonation. Therefore, this innovative methodological strategy demonstrated its suitability and relevancy for revealing unknown compounds generated from water treatment, and permitted to generate new results regarding specifically the impact of ozonation on estrone-3-sulfate. These results confirm that ozonation is effective at removing E1-3S in drinking water and indicate that the by-products generated have significantly lower estrogenic activity.

Identification and structural elucidation of ozonation transformation products of estrone

Background

Quantitative methods for the analysis of contaminants of emerging concern (CECs) are abundant in the scientific literature. However, there are few reports on systematic methods of identification and structural identification of transformation products. For this reason, a new method based on high-resolution mass spectrometry and differential analysis was developed in order to facilitate and accelerate the process of identification and structural elucidation of transformation products CECs. This method was applied to the study of ozonation transformation products (OTPs) of the natural hormone estrone (E1).

Results

A control compare trend experiment consisting in the comparison of a control sample to several samples having been exposed to decreasing concentrations of O_3(aq) indicated that 593 peaks could be associated with OTPs. After applying various filters to remove background noise, sample contaminants and signal spikes, this data set was reduced to 16 candidate peaks. By inspection of the shape of these peaks, only two compounds OTP-276 (m/z 275.12930) and OTP-318 (m/z 317.14008) were considered as good candidates for further study. Multi-stage tandem mass spectrometry (MSⁿ) experiments of SPE extracts of the ozonated samples of E1 and of a deuterium-labeled analogue (E1-d₄) showed that OTP-276 and OTP-318 had carboxylic acid and hydroxyl functional groups, as previously reported for OTPs of other hormones. Structures for these two compounds were proposed based on their MSⁿ spectra.

Conclusion

These results indicate that the method proposed is a systematic and rapid approach to study transformation products of CECs.